Author: Conservation Sense and Nonsense

Let Evolution Lead the Way to Adaptation and Survival of Life

“What exists now can only ever come from what came before.” –Thomas Halliday, Otherlands

Otherlands, A Journey Through Earth’s Extinct Worlds was written by a paleontologist using the latest scientific techniques available. (1)  Paleontology has advanced far beyond digging up fossils.  Computer and DNA analysis enables paleontologists to reconstruct models of whole animals from bone fragments as well as describe the lifestyle of extinct animals such as what they ate and what ate them. 

Geologic periods described by Otherlands. Source: Wikipedia

Thomas Halliday puts this knowledge of some of the 5 billion species that have gone extinct in the 4.6 billion years that Earth has existed into the context of geological and biological changes that caused their extinction.  He describes vivid scenes of specific places at specific times, starting 500 million years ago (mya), a geological period when we can recognize most of the phyla (major groups of animals sharing characteristics) that exist today. These snapshots of deep time illustrate that “Environments shape their inhabitants as much as their inhabitants shape them.” (1)

In this article, we will visit a few of these scenes that demonstrate the biological innovations resulting from evolution and the associated geological and atmospheric events.  And we will tell you about how modern conservation methods are often working at cross purposes against evolution and adaptation of life as it copes with catastrophic challenges. 

Biological Innovation

Primitive life is said to have existed on Earth 3.7 billion years ago (bya).  All life that presently exists on Earth is said to have evolved from the first life forms, although the common ancestor is yet to be identified.  No life on Earth is truly alien.

The diversification of life on Earth began to accelerate when cyanobacteria developed the ability to photosynthesize about 3 bya.  Photosynthesis converts sunlight to energy by consuming carbon dioxide, creating carbohydrates that feed plants and storing carbon in plants and the soil, while emitting oxygen into the atmosphere as a by-product.

This evolutionary innovation is responsible for the abundance and diversity of plants today. It is an important factor in the balance of carbon dioxide and oxygen in the atmosphere, which is one of the most important factors in the Earth’s climate.  More plants also mean more food for animals that evolve alongside plants, often forming relationships with one another. 

The first mass extinction, roughly 445 million years ago (mya), is the only mass extinction caused by a rapid change in the Earth’s climate from tropical to glacial, which is equivalent to saying the atmosphere changed from predominantly carbon dioxide to predominantly oxygen, the opposite of our currently changing atmosphere and climate. 

Carbon dioxide levels are said to have dropped from 7,000 parts per million (ppm) to 4,400 ppm during the Ordovician extinction event that killed about 85% of plant and animal species.  Currently our carbon dioxide level is about 420 ppm, just a fraction of what it was during the Ordovician period.  In the context of the history of Earth, the climate we are experiencing is mild, a reminder of the potential for a much more extreme climate in the near future.

This graph of global mean surface temperature on Earth in the past 485 million years tells us the Earth’s climate has been mild since humans evolved. The graph should help us understand the potential for the Earth’s climate to increase beyond the tolerance for human life.

Comparing contemporary sea levels with those in deep time is another way to appreciate the potential for devastating changes in the future.  20,000 years ago, at the height of the last ice age, sea levels were 120 meters lower than they are now.  Conversely, sea levels were highest during the mid-Silurian period, 430 mya, when sea levels were between 100-200 meters higher than they are now and atmospheric carbon dioxide concentrations were high. 

Although the causes of the drastic change in the atmosphere and therefore the climate during the Ordovician period are still debated, the advent of photosynthesis is considered a factor.  The development of fungi enabled plants to move from water to land by delivering moisture from soil to roots of plants, greatly increasing abundance and diversity of plants. About 80% of plants today receive much of their nutrients and moisture through mycorrhizal fungi. 

The photosynthesizing capabilities of plants is one of the ways greenhouse gas emissions, currently causing global warming, can be reduced.  Yet, we are using pesticides to kill plants that native plant advocates have arbitrarily decided “don’t belong.”  Pesticides also kill fungi in the soil that enable plants to survive during drought conditions created by global warming.  This is one of many examples of how management strategies used by humans are counteracting the accomplishments of evolution that occurred long before humans existed or began to think they were competent to “manage” nature.

Plant Evolution Timeline

To make a long, complicated story short, we’ll focus on the major plant groups we recognize today by starting with seedless land plants that reproduce by dispersing spores, such as mosses and ferns that evolved from algae about 460 mya. 

Gymnosperms, which we recognize today as conifers, cycads, and Gingkos, are seed-producing plants that evolved about 300 mya.  Early species of gymnosperms formed huge forests. The carbon they stored became the coal fields of today when they died during the Carboniferous period (360-300 mya).   Today, we draw our fossil fuels from these coal and oil basins.  They provide most of our energy, while releasing greenhouse gases causing climate change.

Continents were close together during the Cretaceous geologic period when angiosperms evolved. Source: Australian Museum

Angiosperms evolved from gymnosperms about 130 mya.  They are flowering plants whose seeds are often encased in fruit. They are by far the most diverse group of land plants.  The evolution of bees around the same time is an example of co-evolution: the flowers feed the bees and the bees pollinate the flowers, delivering pollen from the male anther to the female stigma.   This sexual method of reproduction creates greater genetic diversity than self-pollination.  Greater genetic diversity creates more opportunities for natural selection to operate on plant variations, which may result in species that are better adapted to existing conditions.   

A recent study (2) found that the decline in the population of bees has increased the frequency of self-pollination of some plant species that are capable of both methods of pollination.  This is an example of evolution at work today.  Plants are responding to the existential need to reproduce in the absence of bees by self-pollinating.   

What evolution has accomplished in the past can be undone.  In this case, our indiscriminate use of pesticides such as neonicotinoids has decimated bee populations. Some plants will adapt to the loss of bees by self-pollinating, but not without some loss of genetic diversity provided by sexual reproduction and consequently the long term fitness of plants to face challenges in the future. 

There’s another trade-off for both plants and bees. Producing nectar and attracting bees with colorful flowers is a big energy expense for plants.  Plants therefore save energy by reducing flower size and color, when they can rely solely on self-pollination for reproduction.  Obviously, self-pollination ultimately results in a loss of food for bees and may accelerate the decline in bee populations, a negative feed-back loop, if you will.

This example is a reminder that evolution is neither positive nor negative.  It is simultaneously both positive and negative.  It is what it is:  an inexorable force for change. 

Evolution of grasses

Grasses and grasslands are late comers to the Earth’s plant kingdom.  Grasses evolved from angiosperms about 70 mya, during the Age of Dinosaurs that abruptly ended 66 mya when an enormous asteroid collided with Earth.  Grasses are wind pollinated and their seeds are dispersed by the wind, which enables them to spread rapidly and widely. 

Grasslands became dominant ecosystems about 30 mya, replacing many forest ecosystems.  With the optimal combination of fuel, heat, and oxygen, wildfires were a factor in the transition from forests to grasslands in many places.  Once again, wildfires in conifer forests are presently playing a role in converting forests to grasslands, suitable to a warmer and drier climate.

The development of enhanced photosynthesis by C4 grasses gave them a competitive advantage in hot, dry places where photosynthesis is suppressed. C4 grasses are more drought tolerant and they store more carbon than their predecessors, C3 grasses. There are only about 60 groups of C4 grasses, including several important food crops, such as maize, sugarcane, and sorghum.  They are found in tropical and sub-tropical regions of Africa and South America and some deserts.  California’s native grasses as well as introduced grasses considered “invasive” are not C4 grasses, according to a list of C4 grasses available on Wikipedia. (3)

Because of their potential to improve drought tolerance and increase productivity and carbon storage, there is great scientific interest in converting C3 grasses to C4 grasses.  Despite decades of effort, agricultural science has not been able to duplicate what the natural forces of evolution have accomplished, reminding us that evolution is more powerful than we are.

The transition from forests to grasslands had a corresponding impact on the evolution of animals.  Some browsers of woody plants learned to be grazers, if they could, while others went hungry, and the diversity and abundance of grazers increased. 

Native plant advocates in California have selected grassland as their preferred ecosystem because it was the dominant ecosystem prior to the arrival of Europeans at the end of the 18th century. They have consistently failed to convert non-native grassland to native grassland in California.  Nor is it clear that there would be any benefit to the environment or to its inhabitants to return to the treeless landscapes of California that existed prior to settlement in the late 18th century.

Where populations of native grazers of grassland were reduced by the activities of humans, many grasslands in California naturally succeeded to shrubs and trees. “Restoration” projects attempt to prevent succession of grasslands. Some of these projects destroy native trees and shrubs (e.g. Douglas fir, coyote brush, juniper, etc.) mechanically and with pesticides to maintain ecosystems as grassland.  

Nativists also want to reintroduce the grazing animals of the pre-colonial period to replace domesticated animals humans introduced because nativists see them as competitors of native animals they consider superior. Where top predators have been killed, these herds of grazing animals outgrow available vegetation unless their numbers are controlled as domesticated animals are.

A recent meta-analysis of 221 studies of the impact of megafauna on plant abundance found, “no evidence that megafauna impacts were shaped by nativeness, “invasiveness,” “feralness,” coevolutionary history, or functional and phylogenetic novelty. Nor was there evidence that introduced megafauna facilitate introduced plants more than native megafauna. Instead, we found strong evidence that functional traits shaped megafauna impacts, with larger-bodied and bulk-feeding megafauna promoting plant diversity. Our work suggests that trait-based ecology provides better insight into interactions between megafauna and plants than do concepts of nativeness.”  (4)

The author of Otherlands agrees that the concept of nativeness is not a useful way to understand the environment or conduct conservation because:  “Where an animal or a plant from one part of the world appears in another, some might use the language of invasion, of a native ecosystem despoiled and rendered lesser by newcomers…In reality, species do move, and the notion of ‘native’ species is inevitably arbitrary, often tied to national identity…There is no such thing as a fixed ideal for an environment…To look into deep time is to see only an ever-changing list of inhabitants of one ecosystem or another…The concept of native that we so easily tie to a sense of place also applies to time…We must avoid putting our own ahistorical spin on what was, although certainly dangerous and unlikely, a journey guided entirely by chance.”  (1)

Migration

The history of evolution is also a history of migration.  The oscillation of the Earth’s climate between freezing cold and blistering heat created and destroyed land bridges that enabled or blocked migration as sea levels rose and fell.  When North America and South America were connected by Central America as a result of lower sea levels and geological events about 3 mya, the plants and animals of those continents were mixed by migration.  Likewise, aquatic life of the Pacific Ocean was separated from the Atlantic Ocean by the Central American land bridge until the Panama Canal was built in 1914.

Geological events also created or destroyed the same opportunities for migration.  The opening and closing of the Strait of Gibraltar is a case in point.  The Mediterranean Sea exists because the Strait of Gibraltar exists.  When the narrow Strait is open, the Atlantic Ocean flows into the Mediterranean Basin, creating the Mediterranean Sea, which is an obstacle for migration of plants and animals between Europe and Africa. 

About 6 mya the Strait of Gibraltar closed because the African tectonic plate moved north, colliding with the European tectonic plate.  The Mediterranean Sea slowly evaporated, concentrating ocean salt from the Atlantic Ocean, laying down a sea bed of salt in the Mediterranean Basin and ultimately creating a migration corridor between Africa and Europe. There is every reason to believe that the Strait could close again.  The Earth’s tectonic plates are in constant motion and there is no reason to believe they will stop moving.

The obsession with “where plants belong” seems to be based on ignorance of the history of dispersal and migration.  Much of China and North America have been in the same latitude since the evolution of angiosperms.  As a result, many of our plant species considered native in Eastern North America are also considered native in China.  These paired species in the same genus are called disjuncts.  There are many woody disjuncts in China and North America (magnolias, persimmons, hickory, catalpa, dogwood, sweetgum, tuliptree, tupelo, sassafras, Virginia creeper, etc) as well as many herbaceous disjuncts (ginseng, lopseed, mayapple, skunk cabbage, etc.). (5) They are different species because they have been separated long enough to change as a result of genetic drift, but are in the same plant lineage, therefore chemically similar and presumably used by the same insects.  The study of these disjuncts says, “Most scientists do not consider long-distance dispersal to have played much of a role.  The prevailing view is that most disjuncts are remnants of genera that were once widely distributed in the northern temperate zone during the Tertiary period [66 mya to 2.6 mya per Wikipedia].  These broad distributions in the northern hemisphere were made possible by recurring land bridges.” (5)

Lateral migration patterns of the past are changing in response to contemporary patterns of climate change.  The temperatures at different latitudes are becoming more similar because Polar Regions are warming at a much faster pace than temperate and tropical latitudes.  Plants and animals escaping extreme heat and associated changes in vegetation are moving to higher latitudes in the Northern Hemisphere and lower latitudes in the Southern Hemisphere.  The increasing similarity of the Earth’s climate is changing wind and ocean currents and contributing to the extreme weather events of our changing climate.  Although there are lessons in the events of deep time, we cannot assume that events in the past are entirely predictive of future events because of the complexity of natural processes and our limited understanding of them. 

Of all the nonsensical conservation strategies humans are presently using, perhaps one of the most damaging is the futile attempt to stop migration. It is one of few survival strategies of plants and animals needed in a rapidly changing climate and it cannot be stopped. 

The project that proposes to shoot barred owls in the Pacific Northwest is an example of a “conservation” project that does not deserve that honorific.  Barred owls have migrated from the East to the West Coasts of North America via the boreal forests of Canada.  This is another instance in which large contiguous stretches of land at the same latitude facilitate the migration of life because there is less variation in climate at the same latitude. 

Source: USFWS

Specialists vs. Generalists

Barred owls are more adaptable than their closely related relative in the same genus, spotted owls.  Barred owls have a more varied diet, they are willing to nest in less dense, second-growth forest, and they have greater reproductive success.  They are therefore perceived as competitors of endangered spotted owls. Instead of letting natural selection identify the winner of that competition, the US Fish & Wildlife Service intends to shoot 500,000 barred owls in the next 30 years based on their belief that spotted owls will benefit.  They do not expect to eradicate barred owls and they made a commitment to continue shooting barred owls in perpetuity.  While we continue to log old-growth forests in which spotted owls live, we will kill barred owls with no expectation that they can be eradicated.

This project is typical of American “conservation” projects that attempt to save a specialist species by killing a generalist species.  This strategy was enshrined in American law by the Endangered Species Act, which is now 50 years old.  Like many 50-year-old public policies, we now know that this conservation strategy is not working because it is inconsistent with evolutionary principles.  Change in nature is inexorable.  Legal mandates are not capable of stopping evolution.  If we had a functional political system, we could stop the greenhouse gas emissions causing climate change, but we don’t.  Therefore, we must rely on evolution to cope with the changes in the environment that we have caused.

The most recent mass extinction occurred 66 mya when an asteroid hit the Earth, ending the Age of Dinosaurs.  About 80% of all plant and animal species became extinct.  The species that survived were the most versatile and the most mobile.  Flying dinosaurs were the only dinosaurs that survived, as birds, perhaps because they were the most mobile.  “Of the specialized insects, 85% were lost and it was the generalists that survived.” (1) 

Mass extinctions have created many vacant ecological niches that are opportunities for experimentation, creating new species.  Some were better adapted than others.  Natural selection determined the winners of competition within ecological niches.  The end of the Age of Dinosaurs created the opportunity for the Age of Mammals, as well as bony fish, marsupials, and lizards. 

In other words, our outdated conservation strategy is wasting our limited resources to save specialized species that are probably doomed to extinction.  And we are doing so at the expense of generalist species that might survive if we would quit killing them.  Keep in mind that 99% of all life forms that have existed on Earth have gone extinct.  At a time when the climate is changing rapidly, the goal of saving every endangered species seems both unrealistic and wasteful of limited conservation resources.

Hybridization

Hybridization is one of the tools of evolution.  Closely related species, usually in the same genus and even family often mate and their offspring often survive to eventually give rise to new species.  Successful hybridization is a means of increasing biodiversity.  Hybridization is sometimes a means of improving adaptability and therefore survival.

Unfortunately, nativists see hybridization as a loss of biodiversity rather than an opportunity to improve adaptability and increase biodiversity.  Their “conservation” projects often attempt to prevent hybridization by killing hybrids.  For example, the plan to kill 500,000 barred owls includes all hybrids of barred and spotted owls.  Because barred owls are more versatile, hybridization with spotted owls could even the playing field with barred owls by expanding food sources and nesting habitats of spotted owls. 

The Spartina eradication project is another example of the pointless eradication of hybrids.  In the case of Spartina, the non-native species grows more densely and it doesn’t die back in winter.  Non-native Spartina provides better storm protection and better habitat for nesting birds.  The Invasive Spartina Project has been spraying hybrid Spartina with herbicides for over 20 years, without total success.  The hybrid looks so similar to native Spartina that 600 genetic tests are required every year to confirm their identification as hybrids before they are sprayed.  The Invasive Spartina Project is a waste of limited conservation resources and it serves no useful purpose.

Evolution vs. Conservation

Otherlands should be required reading for those who are engaged in the “restoration” industry.  Some of the methods and goals of conservation are at odds with the mechanisms of evolution that have ensured the survival of life on Earth for nearly 4 billion years. 

  • The use of pesticides by “restoration” projects is antithetical to the goal of conservation because they do more harm than good.
  • Migration is a means of species survival.  Natural migration of plants and animals cannot and should not be stopped.
  • Humans cannot duplicate the forces of evolution.  Natural selection is the most powerful, efficient, and effective method of determining the winners of competition.
  • Hybridization has the potential to improve adaptability of closely related plants and animals.  Hybridization cannot and should not be stopped.
  • Resources being wasted in the attempt to stop the natural forces of evolution should be redirected to reducing greenhouse gas emissions causing climate change.  Such efforts are appropriately called “conservation.”
  1. Thomas Halliday, Otherlands, A Journey Through Earth’s Extinct Worlds, Random House, 2023
  2. https://www.nytimes.com/2024/01/04/science/flower-sex-evolution-bees.html?searchResultPosition=1
  3. https://en.wikipedia.org/wiki/List_of_C4_plants
  4. Erik Lundgren et.al., “Functional traits—not nativeness-shape the effects of large mammalian herbivores on plant communities,” Science, February 2, 2024
  5. David Yih, “Land Bridge Travels of the Tertiary:  The Eastern Asian-Eastern North American Floristic Disjunction, Arnoldia, 2012

EPA’s Biological Evaluation of Rodenticides is Green Wash for Island Eradications

The Endangered Species Act requires that the Environmental Protection Agency (EPA) conduct biological evaluations (BE) of the impact of pesticides on threatened and endangered species protected by the ESA.  For example, when the EPA published its final evaluation of glyphosate in 2021, it informed us that glyphosate is “likely to adversely affect” 93% of legally protected endangered and threatened plants and animals.

Source: EPA Biological Evaluation for Glyphosate

The EPA published a draft of a biological evaluation (BE) of 11 rodenticides in November 2023, which is a free gift to the island eradication industry.  The deadline for making comment on this draft is February 13, 2024.  Public comment can be made HERE. 

The EPA’s biological evaluation for rodenticides reached the conclusion that rodenticides used in island eradications have “no effect” on any aquatic plant or animal, including birds in the aquatic food web and amphibians with a fully aquatic lifestyle.  They made this “no effect” determination without evaluating any of those species, based on their claim that the Product Label for the rodenticide used in island eradications prohibits its use in water, which is not true.  EPA also extended this “no effect” determination to all species under the jurisdiction of National Marine Fisheries Services.  (1)

In fact, the standard Product Label for brodifacoum does not explicitly prohibit the use of the product in water.  It merely warns of the deadly consequences for aquatic species if used in water:  “This product is extremely toxic to birds, mammals, and aquatic organisms.  Predatory and scavenging mammals and birds might be poisoned if they feed upon animals that have eaten bait. Runoff may be hazardous to aquatic organisms in water adjacent to treated areas.  DO NOT contaminate water when disposing of equipment wash water or rinsafe.”  The standard Product Label also explicitly allows aerial broadcast of rodenticides for island eradications.  (2)  In other words, it’s dangerous to apply rodenticides to water, but, in fact, it often happens during island eradications.  The biological evaluation asks the public to believe the EPA’s claim that rodenticides are not used in water despite ample evidence that rodenticides land in water during aerial broadcasts on islands.

Although the standard Product Label acknowledges the potential that rodenticide runoff “may be hazardous to aquatic organisms in water adjacent to treated areas,” EPA’s biological evaluation dismisses that possibility by claiming that “use patterns preclude spray drift and runoff exposure.”  EPA’s biological evaluation provides no evidence in support of that claim and that claim is explicitly contradicted by the EPA in its evaluation of the proposed island eradication on the Farallon Islands as well as the considerable record of contamination of the aquatic food web during completed island eradications, as explained below.

Supplemental Product Labels are required for island eradications because they require greater quantities of rodenticide bait than allowed by standard Product Labels and modifications in application methods. The Supplemental Product Label required for island eradications explicitly permits the use of brodifacoum on water (3):

  • Elevated and floating bait stations are allowed in intertidal zones above the mean low tide mark and below the mean high tide water mark.
  • Broadcast applications are allowed in coastal areas above the mean high tide water mark.  Conversely broadcast applications are prohibited below the mean high tide water mark. 

The cited Supplemental Product Label for Wake Island was recently published in preparation for a second attempt to eradicate rats on Wake and 2 adjacent islands.  The first attempt in 2012 was a failure.  Here is a photo of this complex of islands:

Wake Island. Source: NASA

As you can see, Wake Island is a narrow strip of land surrounding a lagoon that is open to the ocean.  Two-thirds of the island is surrounded by sandy, tidal beaches.  Scrub vegetation is in the intertidal zone.  A portion of the island’s vegetation is wetland.  It defies belief that it is possible to aerial broadcast rodenticide from helicopters (or float bait boxes in the intertidal zone) on Wake Island without getting rodenticide in the water. 

The published study about the failure of the first attempt to eradicate rats on Wake Island was written by the organizations that conducted the project.  It reports that rats were found on the island less than a year after the aerial broadcast and supplemental hand-applications were done. The study makes no mention of non-target deaths of any animals.  The study speculates that the failure of the attempt was the result of not applying the rodenticide everywhere rats were living.  They will soon try again, using the same methods.  Rodenticide bait will surely end up in the water.  More non-target animals will undoubtedly be killed.  But the public will not learn about either of those issues, because the monitoring and reporting is entirely controlled by the perpetrators of these projects. (4)

Keep in mind that there are 239 taxa living in the intertidal zone around the Farallon Islands, according to Appendix J of the Final Draft of the Environmental Impact Statement for the proposed Farallon Islands.  No Supplemental Product Label has been granted yet for the proposed island eradication on the Farallon Islands, but the Farallones are included on the list of 29 island eradications (below) in the EPA’s biological evaluation, which the BE says will be done within the next 5-7 years.

Source: EPA Biological Evaluation of Rodenticides

Contamination of the aquatic food web during island eradications is inevitable

EPA made a public record of its concerns about contaminating the aquatic food web during island eradications in its letter of December 9, 2013 regarding “EPA comments on the Revised Draft Environmental Impact Statement for the South Farallon Islands Invasive House Mouse Eradication Project.” (5)  In response to the claims of the DEIS for the proposed island eradication that “the bait deflector will minimize, and in several places, prevent bait drift into the marine environment,” the EPA said, “The EIS should be clear that bait drift would occur.”

The EPA’s letter of December 9, 2013, goes on to report previous experience with aerial broadcast applications on Palmyra Island and states:  “For future operations, the potential for bait to enter the marine environment must be a factor in the aquatic risk assessment and further methods to minimize the amount of bait entering the marine environment should be fully explored. The amount of bait that enters the aquatic environment from an aerial broadcast depends on shoreline configuration, island topography, overhanging vegetation, bird activity affecting flight lines, wind strength and direction, weather conditions, and pilot experience. On islands where these factors increase the potential for bait to enter marine environments, additional mitigation measures may be needed to protect sensitive marine environments.” (5)

Based on those concerns about contamination of the marine food web, the EPA’s letter of December 9, 2013 expresses these specific concerns about the proposed aerial broadcast application on the Farallon Islands:  “Discuss and consider the factors that increase the potential for bait to enter marine environments that are identified above. Especially relevant are the irregular shoreline, the excessive bird activity from gulls, and the proposal to fly steep areas a second time (shorelines on the Farallones are steep) to increase the application rate in these areas.” (5)

Given the EPA’s explicit admission that aerial broadcast of rodenticides on islands have contaminated the marine food web in the past and are likely to do so in the future, the EPA is not in a position to now categorically deny that “use patterns preclude spray drift and runoff exposure,” as it attempts to do in the draft biological evaluation.  Nor is the EPA in a position to categorically deny that aquatic species will be adversely affected by rodenticide bait that will inevitably land in the water surrounding the Farallon Islands, as it attempts to do in the draft biological evaluation.

Farallon Islands, NOAA

The deadly track record of island eradications

The aerial application of rodenticide to kill rats on Anacapa Island in 2001-2002 was the first of its kind in North America. The project was complicated by the need to spare a population of endemic native mice on Anacapa.  Over 1,000 native mice were captured before the aerial application of rodenticide and released back on the island after the poison was no longer effective. Clearly, mice aren’t considered a problem on islands, unless they have the bad luck of being non-native.  Whether native or non-native, they are prey for many bird species.

Most of the raptors on Anacapa were removed before the rodenticide drop.  Of those that were left behind, 3 barn owls, 6 burrowing owls, and a kestrel likely died from rodenticide bait or eating poisoned mice.  94 seed-eating birds were also found dead after the poison drop.  The study says that these collateral kills were consistent with other similar projects.

Bird scavengers such as gulls, vultures, and condors are also vulnerable to secondary poisoning by poisoned rodents.  Shortly after the Anacapa poison drop, dead seabirds washed up on the shore near the Santa Barbara harbor.  UC Santa Barbara’s daily newspaper said, “…a strong correlation exists between the National Park Service’s most recent airdrop of pesticide on Anacapa Island and the dead birds.”  These deaths weren’t reported by the study of the success of the poison drop.  As usual, the study was done by supporters of the project, with little interest in finding more collateral death from the drop.  The public is not allowed to observe island eradications.  Therefore, the public’s only source of information is those who are directly involved in the aerial application of rodenticides. 

“In October 2008, two helicopters dropped approximately 46 metric tons of Brodifacoum 25-W bait on Rat Island’s 2800 hectares, supplemented by hand application of bait around the island’s freshwater lakes. This rodenticide is known to be highly toxic to birds. Some nontarget mortality was expected, but the actual mortality exceeded the predicted mortality. Forty six Bald Eagles died (exceeding the known population of 22 Bald Eagles on the island); toxicological analysis revealed lethal levels of brodifacoum in 12 of the sixteen carcasses tested. Of the 320 Glaucous winged Gull carcasses, toxicology tests implicated brodifacoum in 24 of the 34 tested. Carcasses of another 25 bird species were found; of these 54 individuals, three were determined by necropsy to have died of brodifacoum poisoning.” (6)

Palmyra Atoll was aerially broadcasted twice with brodifacoum rodenticide in 2011 as well as a follow-up hand broadcast application.  The study of that project reported:  “We documented brodifacoum residues in soil, water, and biota, and documented mortality of non-target organisms. Some bait (14–19% of the target application rate) entered the marine environment to distances 7 m from the shore. After the application commenced, carcasses of 84 animals representing 15 species of birds, fish, reptiles and invertebrates were collected opportunistically as potential non-target mortalities. In addition, fish, reptiles, and invertebrates were systematically collected for residue analysis. Brodifacoum residues were detected in most (84.3%) of the animal samples analyzed. Although detection of residues in samples was anticipated, the extent and concentrations in many parts of the food web were greater than expected.”

These published studies are helpful to understand the scale of water contamination and collateral deaths of non-target animals, including aquatic animals.  However, they are just the tip of the toxic iceberg because little monitoring and testing is done on the many marine animals that have been killed in proximity of these projects.  Robert Boesch is a retired pesticide regulator for the EPA and the Hawaii Department of Agriculture.  Presently, he is Visiting Colleague at University of Hawaii at Manoa.  He has written an unpublished discussion paper (7) that reports:

  • Strandings of whales, some hemorrhaging, occurred within 60 days following anticoagulant bombardment.
  • Unusual mass strandings of hemorrhaging dolphins occurred in San Diego and Hawaii years after anticoagulant bombardment.
  • There is very little known about the fate of anticoagulant residues in the oceans.
Source:  Robert Boesch discussion paper available HERE
.

The documented deaths of non-target animals caused by island eradications are direct poisonings by eating bait on the ground or by secondary poisoning by eating poisoned rodents.  The EPA biological evaluation attempts to dismiss the potential for secondary poisonings by citing a study (Baldwin 2021) that claims most rodents die in their burrows after eating the poison, making them unavailable to be eaten by other animals.  This study is not relevant to island eradications because it was conducted on ground squirrels (not rats or mice), it used a first generation rodenticide (diaphacinone) which is not used in island eradications, and most applications were burrow baits, rather than aerial broadcast. 

What’s at stake?

About 1,200 island eradications have been done all over the world over the last 30 years, with mixed success. The EPA’s biological evaluation announces the intention to approve 29 new island eradications in US waters within the next 5-7 years, including the Farallones.  In the case of Hawaii, the list says “all islands.”  Many of the listed islands are actually a complex of islands, such as those in Boston Harbor. Many of the islands are residential communities, such as Nantucket and Martha’s Vineyard. As presently drafted, the biological evaluation will make it possible to approve those projects without addressing the considerable evidence that these projects are killing thousands of birds and animals and contaminating the ocean surrounding island eradications.

The Bottom Line

The draft biological evaluation is unacceptable because it gives the public the false impression that island eradications with rodenticides are harmless, when they clearly are not. It confers EPA’s blessing on island eradications by refusing to evaluate endangered species that may be harmed by island eradications.  It ignores the evidence that rodenticide applications have killed many terrestrial and aquatic animals and contaminated the water.

The biological evaluation must be revised to correct these flaws in the present draft:

  • Exposure to rodenticides during island eradications must be based on Supplemental Product Labels for island eradications, not standard Product Labels that do not apply to island eradications. 
  • The revised biological evaluation must evaluate all legally protected animals exposed to rodenticides during island eradications, including aquatic animals.  Both bioconcentration and bioaccumulation must be considered in the determination of exposure to rodenticides.  “No effect” cannot be assumed without such evaluation.
  • The revision must provide evidence in support of the claim that there is no drift or run-off of pesticide from aerial broadcasts done on islands or delete that claim, which is contradicted by actual experience with island eradications. 
  • The revision must remove the claim that rodents die in their burrows after eating rodenticide bait (Baldwin 2021) because the study was done on a different animal, using a different rodenticide, and a different application method. 

Update:  The final version of the EPA biological evaluation of rodenticides is unchanged from the draft.  It continues to make “no effect” determinations for all aquatic species and critical habitats under the jurisdiction of the National Marine Fisheries Service.  It continues to list the same off-shore islands (including the Farallons) where “APHIS is planning to conduct rodent eradication projects for the benefit of seabirds and other wildlife on these islands in the next five to seven years.”

The only changes it acknowledges making are the removal of some of the mitigation measures from the draft.  December 9, 2024

  1. EPA Biological Evaluation of Rodenticide
  2. Label Amendment for Brodifacoum -25W Conservation, November 12, 2019
  3. Supplemental Label for second attempt to eradicate Polynesian rates on Wake Atoll following previous attempt in 2012, December 6, 2021
  4. “The Wake Island Rodent Eradication: Part Success, Part Failure, but Wholly Instructive,” Island Conservation, et.al., Proc. 26th Vertebr. Pest Conf. Published at Univ. of Calif., Davis. 2014
  5. “EPA comments on the Revised Draft Environmental Impact Statement for the South Farallon Islands Invasive House Mouse Eradication Project.” December 9, 2013
  6. “The rat island rat eradication project:  A critical evaluation of nontarget mortality,”  prepared by The Ornithological Council, December 2010 
  7. See attached file:
boesch-contamination-of-marine-mammals-by-rodenticide-2-1Download

For US Fish & Wildlife Service “Management” Means Killing

“It makes me sad, but range expansions are a part of natural systems. We just happened to be watching when one occurred. Even if [we’re to blame], we’re probably going to have to live with it.”
Eric Forsman, US Forest Service

US Fish & Wildlife Service (USFWS) proposes to kill 470,000 barred owls in the next 30 years in an effort to save the northern spotted owl (NSO) and a closely related sub-species in California.  The deadline for making a comment on this proposal is January 16, 2024.  Instructions for making comments are available HERE. 

Today, I will tell you about this proposal, how it came about, and why I am opposed to the proposal.  I provide links to the source documents so you can read them yourself.  I hope this information will help you reach your own conclusions about the plan and submit a public comment. 

USFWS Barred Owl Management Strategy

The purpose of the Barred Owl Management Strategy is protection for the dwindling population of northern spotted owls (NSO) in the Pacific Northwest (Washington, Oregon, and Northern California).  NSOs were classified as a threatened species by USFWS in 1990.  The first Recovery Plan for NSO, published in 2011, identified habitat loss and barred owls as the primary threats to NSOs.  The most recent Recovery Plan has added “past habitat loss, continued timber harvest, and wildfire” to the list of threats to NSOs.

Northern spotted owl. USFWS

The Barred Owl Management Strategy also proposes “management” of barred owls to protect the California spotted owl (CSO), which is a subspecies of NSOs.  Although endangered status for CSO was proposed in February 2023, endangered status has not been granted.  Yet, USFWS proposes to extend the same lethal removal measures used to protect NSOs to CSOs.  In addition to the threats to NSOs, California spotted owls are also threatened by fragmented habitat and forest mortality caused by drought and correlated disease, which have killed over 300 million conifers in California in the past 10 years.

Source:  Barred Owl Management Strategy

Despite the many threats to spotted owls, the Management Strategy intended to protect them addresses only one of those threats:  barred owls.   It makes no proposals for improving or expanding habitat or addressing the impact of climate change on forests.

The Barred Owl Management Strategy is a voluntary plan.  Federal agencies in spotted owl territory (Bureau of Land Management, US Forest Service, and National Park Service) will be “encouraged” to implement the plan.  If state, commercial, private property, and tribal land owners choose to participate they will be granted the same “take” permits required by the Migratory Bird Treaty Act that federal land managers will be granted, so long as they agree to follow the protocol for “removing” barred owls from their properties.

The word “removal” in the context of the Management Strategy means “lethal removal.”  The protocol requires that barred owls be found by playing a recording of their distinctive call (described as “who cooks for you?”) and shooting the owl as it flies toward the call and the shooter.  If guns are not allowed where barred owls are found, they must be captured and euthanized.  Hybrids of barred owls and spotted owls will also be killed, despite the fact that accurately identifying hybrids is considered difficult, particularly in subsequent generations.    

Because the Management Strategy is not mandatory, the total number of birds that will be killed can only be estimated.  If all property managers choose to implement the Strategy, approximately 470,000 barred owls would be killed in the next 30 years.  Although the Strategy covers only a 30 year time frame, “barred owl management will be required at same level for the long term” because “Their populations will continue to produce young that can disperse within and beyond the current range of barred owls.” (1)  The estimated current population of barred owls in study areas of the Management Strategy is only 102,000.  Clearly the lethal removal of barred owls is not expected to keep pace with the reproductive success of barred owls.  The killing of barred owls will continue forever, although there is no expectation that they will be eliminated.

Source:  Draft Environmental Impact Statement for Barred Owl Management Strategy

How were barred owls selected as the scapegoat?

When northern spotted owls were designated as “threatened” in 1990 it triggered the legal protections conferred by the Endangered Species Act. In 1994, the Forest Service and the Bureau of Land Management published the EIS for the Northwest Forest Plan.  It created 24 million acres of reserve areas where logging was prohibited to preserve spotted owl habitat.  The reserve areas protected approximately 80 percent of the remaining old growth forests in the Pacific Northwest from timber harvesting.  Obviously, the plan had a negative impact on the timber industry and those who were employed by the industry.  Between 1980 and 1998, 23% of logging jobs were lost, triggering the Timber Wars.

The rate of decline of spotted owl populations in the Pacific Northwest decreased when most logging in old-growth forest was stopped by the Northwest Forest Plan, but began to accelerate again in about 2008.  USFWS attributes that increase in the rate of population decline to competition from barred owls and that theory is supported by several studies.

Barred Owl. GNU Free Documentation License

Barred owls are native to North America.  They have been migrating from their historic range in the north and south east of the US to the west coast of North America since about 1900.  Barred owls were first seen on the west coast of North America in British Columbia, Canada around 1959.  They were first documented in Washington in the 1970s and have continued moving south from there. 

Barred owls have successfully competed with spotted owls in their expanding territory because they are larger than spotted owls, they eat a wider variety of prey, they have greater reproductive success, and they are able to live in forests where spotted owls cannot.  Spotted owls are restricted to old-growth forests with large trees and dense canopies, while barred owls often live in second-growth (previously logged) forests and even wooded urban areas. 

The Management Strategy speculates that the omnivorous diet of barred owls will devastate the food webs in the new territory they occupy, although the Strategy offers no evidence to support that theory.  In fact, as barred owls expanded their territory through the Canadian boreal forest, such devastation was not reported.  Barred owls are not considered “invasive” in Canada.

The impact of barred owls on spotted owls was first observed by Lowell Diller, a wildlife biologist who worked as a consultant to Green Diamond Resource Co., a logging company managing timberland in Humboldt and Del Norte counties in Northern California.  Mr. Diller was also an adjunct professor in the Department of Wildlife at Humboldt State University.

Owls, including barred owls, are protected by the Migratory Bird Treaty Act.  Mr. Diller applied for permits to kill barred owls on the property of Green Diamond Resource Co. as an experiment to determine the impact of barred owls on spotted owls.  He described his project in an article in the Marin Independent Journal:  “In 2009,…Diller set aside patches of timberland to remove barred owls.  In other patches, he did nothing.  After four years, he would see how northern spotted owl numbers differed in the areas with and without barred owls…The study is the first to prove his treatment works.” To be clear, his “treatment” was to shoot barred owls. Mr. Diller also described how upsetting it was to kill birds. 

Green Diamond applied for permits and has continued to kill barred owls on its property.  That commitment has ensured that Green Diamond’s current rate of logging can continue.  The Green Diamond spokesman explained:  “’When you can protect and sustain a business and jobs and also conserve the northern spotted owl,’ he said, ‘why not do it.’” (Marin Independent Journal)

Sierra Pacific Industries is also killing barred owls on its property.  Sierra Pacific Industries in Shasta County is the largest private land holder in California and the second largest lumber producer in America.   

On the basis of the success of Diller’s study, USFWS approved a pilot project to kill barred owls in other places where spotted owls live.  The pilot project killed about 3,000 barred owls.  When the project was completed in 2021, they reported, “The removal of barred owls had a strong, positive effect on the survival of northern spotted owls and a positive, but weaker, effect on recruitment of spotted owls.” (2) The Barred Owl Management Strategy is based on the success of the pilot study. 

In other words, killing barred owls has enabled the timber industry in Northern California to continue their logging operations.  It has also removed the pressure to expand reserve areas to protect spotted owls, even though many scientists believe such expansion would be more effective than killing barred owls to save spotted owls:  “’The bottom line is that extinction rates went down when the amount of habitat went up,’ U.S. Geological Survey biologist Katie Dugger, lead author of the 2015 demographic study, said in a presentation on the findings last fall. ‘Spotted Owls cannot exist without old-growth forest. And now we’re talking about two species trying to use the same space, so in fact we need more of it.’” (3)

Specific Flaws in Barred Owl Management Strategy

The Barred Owl Management Strategy is based on several outdated notions about nature that have been cast in the concrete of American law. The Endangered Species Act is based on assumptions about nature that were conventional wisdom at the time the law was passed 50 years ago, in 1973.  Evolution was considered a series of events that occurred in the distant past and is no longer actively changing plants and animals.  At the time the ESA was passed, evolution was not believed to occur within a time frame observable by humans.  Nature was perceived as reaching an “equilibrium state” that was stable over long periods of time.  Early conservation efforts were therefore based on the assumption that once achieved, an equilibrium state could be sustained if left undisturbed in nature preserves. (4)

We now know that these assumptions are mistaken.  In the past 50 years, climate change and advances in paleontology have taught us that nature is inherently dynamic and we are usually powerless to stop it from changing even when we try.  When a law is designed to control nature, we should expect some conflict between static law and dynamic nature.  Fifty years after the Endangered Species Act was passed, that conflict is becoming progressively more apparent and problematic. 

These are the specific flaws in the Barred Owl Management Strategy that are the result of mistaken assumptions about nature:

  • Barred owls should not be considered “invasive” on the west coast of the US because the expansion of its range is a natural phenomenon that cannot and should not be stopped.

USFWS designates barred owls on the west coast as “invasive” by fabricating a story about the route barred owls took from their historic range in the east to their expanded range in the west that is not consistent with the facts.  Although USFWS admits that the route that facilitated expansion is “not well documented,” they claim there is evidence of anthropogenic change across the Midwestern Prairie that supports that specific route:  “…the historical lack of trees in the Great Plains acted as a barrier to the range expansion and that increases in forest caused by the anthropogenic impact of European settlement enabled the westward extension of the barred owl range. These include anthropogenic impacts such as fire exclusion and suppression, bison and beaver extirpation, deer and elk overhunting, establishment of riparian forests, and extensive planting of trees and shelterbelts in the northern Great Plains…” (2)    Although that is an accurate description of anthropogenic changes in the Midwestern Prairie, it is irrelevant to the expansion of the range of barred owls, because that wasn’t the route they took to the west coast.

The legal definition of invasive species enables USFWS to designate barred owls on the west coast as “invasive” based on their claim that the expansion route was through the American Midwest as a result of anthropogenic change. If non-indigenous humans are considered the cause of a change in ranges of plants and animals, the species is considered “invasive” where it did not exist prior to the arrival of Europeans. Labelling any plant or animal “invasive” makes it a target for eradication.   However, the theory of a midwestern expansion route for barred owls is not consistent with the facts:

Source:  Barred Owl Management Strategy

This map clearly shows that the route used by barred owls to expand their range to the west coast was through the boreal forests of Canada, which were not the result of anthropogenic change.  The boreal forests of Canada have existed since the Ice Age ended 10,000 years ago.  The map does not show the historic or current existence of barred owls in the American Midwest. 

The expansion route of barred owls to the west coast through Canadian forests is also consistent with the record of their arrival on the west coast.  They were seen first in the west in 1959 in British Columbia, Canada, at the northern edge of their current range.  They were first seen in the US in Washington in the 1970s.  Their range expansion continues to the south.  This sequence of events is not consistent with the claim that they arrived on the west coast via the American Midwest.

Claiming that barred owls are “invasive” enables USFWS to justify their extermination, as many of their eradication projects do:  “Yes, wildlife removal has been used as a management tool by many agencies across the country to control invasive species such as invasive carp, Burmese python, feral hogs, rats, mongoose, and nutria. Invasive species can thrive in areas where they do not naturally occur.” (1) That list of animals being killed by USFWS is far from complete. 

This is not a trivial matter.  Climate change requires that plants and animals move to find the conditions needed for their survival.  Preventing the migration of plants and animals as the climate and the environment change will doom them to extinction.  Designating barred owls on the west coast “invasive” has dangerous implications for many plants and animals that must move to survive in a rapidly changing climate.  The Management Strategy should not set this dangerous precedent. 

  • Interbreeding of spotted owls and barred owls is a natural phenomenon that cannot and should not be stopped.  Hybrids of spotted and barred owls should not be killed.

Hybridization is not only common, it can result in the creation of new species more rapidly than other forces of evolution, such as mutation and natural selection:  “Hybridisation also offers shortcuts on the long march to speciation that do not depend on natural selection at all.” (5)

More than 99% of all species that ever lived on Earth, amounting to over five billion species, are estimated to have died out. Yet there are currently around 8.7 million species of eukaryote (organisms whose cells have a membrane-bound nucleus) globally. (Wikipedia) Biodiversity on Earth has increased partly because of hybridization, which has often enabled adaptation to changed environmental conditions.

There are many important examples of hybridization among animal species, most notably the history of hybridization of our species, Homo sapiens.  Humans are now the sole surviving species of genus Homo.  Our genome contains the relicts of the genes of other members of our genus that are now extinct, which indicates hybridization with other hominoid species.  The modern human genome contains 1-4% of Neanderthal genes. (5)

There are also many examples of hybridization of plant species that contributed to biodiversity.  In a recently published study of the evolution of oaks, scientists traced the 56 million year evolutionary history of roughly 435 species of oak across 5 continents where they are found today.  Hybridization was instrumental in the formation of oak species and the ability of oaks to survive in different climate conditions.  The article in Scientific American about the genetic study of oak species concludes:  “A firm grasp of when, where and how oaks came to be so diverse is crucial to understanding how oaks will resist and adapt to rapidly changing environments. Oaks migrated rapidly as continental glaciers receded starting around 20,000 years ago, and hybridization between species appears to have been key to their rapid response. The insights we can gain from elucidating the adaptive benefits of gene flow are critical to predicting how resilient oaks may be as climate change exposes them to fungal and insect diseases with which they did not evolve.”

The bias against hybrids is a reflection of nativist ideology in the natural world.  Nativists call hybridization “genetic pollution.”  Unfortunately, hybridization is seen by nativists as the loss of a “pure” native species rather than the potential for a new species that is better adapted to changing environmental conditions.  The proposal to kill hybrids of barred and spotted owls is a symptom of the nativist bias that is typical of most public agencies. 

Barred and spotted owls are closely related.  They are in the same genus, just as Neanderthals and Homo sapiens were in the same genus.  Their interbreeding is both predictable and potentially beneficial to spotted owls because barred owls are better adapted to current conditions. The hybrid has the potential to produce a new species that is better adapted to compromised forest conditions than the spotted owl.  Although there is risk in hybrids, in the case of spotted owls the risk is worth taking because many scientists predict that the northern spotted owl will soon be extinct.  Hybridization may be more helpful to the spotted owl species than killing barred owls.

  • The Barred Owl Management Strategy should not be extended to California spotted owls.

The Barred Owl Management Strategy depends on the legal protections of the Endangered Species Act.  Both barred owls and spotted owls are protected by the Migratory Bird Treaty Act.  Therefore, “take” permits must be granted to kill barred owls.  The protected status of northern spotted owls justifies take permits, but should not be extended to California spotted owls (CSO) that are not legally protected.  Issuing take permits to kill barred owls to save California spotted owls makes a mockery of both the ESA and the Migratory Bird Treaty Act.  It implies that USFWS can find loopholes in environmental laws intended to protect nature, whenever they wish.  It undermines the public’s faith in government when public agencies are perceived as arbitrary and capricious.

Killing barred owls in CSO territory cannot be justified because there are few barred owls in their territory and threats to the CSO population are unrelated to the existence of a few barred owls. (See map of barred owl distribution in California below.) Shooting barred owls will not stop the wildfires, droughts and diseases killing their habitat.  The proposed Management Strategy is irrelevant to the survival of CSO. 

Source: Spotted Owl Observation Database, California Department Fish and Wildlife, 2019
  • There is no reason to kill barred owls in Marin and Sonoma counties in the San Francisco Bay Area because the population of Northern Spotted Owls is stable and there are very few barred owls. 

The Marin/Sonoma County Management Zone designated by the Management Strategy includes all lands within the named counties. Conditions in Marin and Sonoma County are substantially different from the rest of the northern spotted owl range. This is the only portion of the northern spotted owl range where barred owls are very uncommon.

The recently completed survey of northern spotted owls in Marin County reports that the population is stable. The survey found nesting pairs of NSOs in all 48 inventory sites.  A small decline in nesting success was not statistically significant.  Two unpaired barred owls were detected on or near Marin County Property or Marin Watershed Property in 2023.  One was removed, the other was not detected a second time. (6)

Source:  Northern Spotted Owl Monitoring on Marin County Parks and Marin Municipal Water Department lands, 2023 Report, Point Blue Conservation.

Despite the lack of evidence that northern spotted owls are threatened by barred owls in Marin County, the Barred Owl Management Strategy considers it the highest priority to kill the few transitory barred owls detected in Marin County.  This is unnecessary overkill that should be removed from the Management Strategy.  It contributes to the public’s perception that the strategy of USFWS is extreme and inconsistent with environmental laws that protect nature.

In conclusion, the Barred Owl Management Strategy is a reflection of the extreme nativist bias of USFWS.  Like many of their projects, USFWS has selected an animal scapegoat for the declining population of northern spotted owls that are not well adapted to changed forest conditions. Selecting an animal scapegoat enables timber companies to continue logging and it is an easy way to avoid addressing the much more complex reasons for challenges to northern spotted owls. For example, killing barred owls won’t do anything to reduce the greenhouse gases causing climate change or restore logged or burned forests. The Barred Owl Management Strategy will employ an army of snipers, but is unlikely to benefit the environment or its inhabitants.  USFWS cannot stop evolution, nor should it try.

Although I have low expectations that 2024 will be more peaceful than last year, in the spirit of hope, I wish you Happy New Year.  Thank you for your readership.

Update, July 2025:  The Northwest Forest Plan has been amended.  The amendment to the plan will enable more logging in the Pacific Northwest.  Https://www.chronline.com/stories/proposed-changes-would-allow-more-logging-on-federal-land-in-the-pacific-northwest,372393

The amendment began during the Biden administration and was approved in May 2025.  The point of the amendment is to “manage” the forest to reduce wildfire hazards.  https://www.fs.usda.gov/r06/planning/northwest-forest-plan-amendment

The stated purposed of the USFWS plan to kill 500,000 barred owls was to save endangered spotted owls.  The plan was created by the timber industry in the Pacific Northwest because killing barred owls on their properties enabled them to get permits needed to continue logging on their properties.

On October 30, 2025, the US Senate rejected an effort to halt the implementation of the Barred Owl Management Plan by a vote of 25-72: https://worldanimalnews.com/2025/10/30/stop-the-slaughter-450000-barred-owls-face-mass-killing-for-so-called-conservation/

However, The Trump administration has also cancelled some grants that funded the plan to kill barred owls in the Pacific Northwest:  https://washingtonstatestandard.com/2025/07/22/plans-to-shoot-thousands-of-barred-owls-in-doubt-after-feds-cancel-grants/

Confusing, isn’t it? The plan lives, but some of the funding for implementation is gone. That’s my best guess.

There is some logic to this sequence of events.  However, I doubt that logic was used to reach this conclusion.  In any case, I am pleased that barred owls will be spared the planned massacre.  However, the loss of federal funding to kill barred owls will not prevent private land owners from killing barred owls.  The revision of the Northwest Forest Plan to enable more logging might make killing barred owls on private land unnecessary. 

  1. Frequently Asked Questions about the Barred Owl Management Strategy
  2. Barred Owl Management Strategy
  3. Sarah Gilman, “Evidence of Absence:  Northern Owls are still vanishing from the Northwest,” Living Bird, April 12, 2016
  4. Holly Doremus, “The Endangered Species Act:  Static Law Meets Dynamic World,” Journal of Law & Policy, Vol. 32: 175-235, 2010.
  5. The Economist, “Match and mix, hybrids and evolution,” October 3-9, 2020, page 67-70. 
  6. Northern Spotted Owl Monitoring on Marin County Parks and Marin Municipal Water Department lands, 2023 Report, Point Blue Conservation.

Deadly Dogma:  Revisiting the Farallon Islands Unnecessary Eradication Project

“The more we know about plans to eradicate harmless mice on the Farallon Islands with rodenticide, the less sense it makes.” – Conservation Sense and Nonsense

Plans to eradicate mice on the Farallon Islands with rodenticide were approved by the California Coastal Commission (CCC) two years ago, on December 16, 2021.  Although CCC approval was contingent on a few conditions intended to reduce the inevitable death of non-target birds and marine animals, it is unclear if CCC will be able to enforce the conditions. Plans seem to be moving forward behind closed doors, so Conservation Sense and Nonsense continues to be concerned about this project. 

First a brief reminder of the project and our objections to it.  House mice were introduced to the Farallon Islands over 100 years ago by ships visiting the island.  There is no evidence that mice harm birds on the Farallons.  The mice are an integral part of the food web, eating primarily vegetation and supplementing that diet with insects during summer months when vegetation is sparse.  The mice are also the prey of hundreds of thousands of birds that live on the islands as well as birds that stop over on their migratory routes.  The mouse population varies throughout the year, dwindling during winter months and increasing in the fall.  When the mouse population declines, food sources for their predators also decline.  That’s when burrowing owls are said to prey on the nestlings of ashy storm petrels.  Though the mice are blameless, the project proposes to kill them all based on the assumption that burrowing owls will not overstay their migratory stop over if food sources are significantly reduced.  The project is expected to kill hundreds—perhaps thousands—of non-target birds who will eat poisoned pellets directly and/or poisoned mice.

The project has always seemed absurd and nothing we’ve learned about it in the past 2 years has made it seem otherwise.  Our last article of 2023 will report new information learned since the project was approved.

Contamination of the food web

Robert Boesch is a retired Pesticide Regulator for the Environmental Protection Agency, region 9 and the Hawaii Department of Agriculture.  Presently, he is Visiting Colleague at University of Hawaii at Manoa.  Based on his research and experience, he has written a discussion paper about island eradications using rodenticides, which he has shared with the California Coastal Commission and many other agencies and organizations.  This entire discussion document is available below as a footnote and this is his summary of “Eradication Programs Eliminating Invasives and their Predators and Scavengers!”

  • Eradication programs for mice and Polynesian Rats are planned for the Farallon Islands, Midway and Wake Island.
  • Brodifacoum, a potent, persistent and bioaccumulative anticoagulant poison is the toxicant. [This is the rodenticide that will be used on the Farallon Islands to kill mice. There are no rats on the Farallons.]
  • Brodifacoum residues have been detected in almost all fish that were collected following treatment of Palmyra, and trace levels were found in 10 percent of the fish after treatment of Wake.
  • Brodifacoum residues in fish caught at Wake increased from trace levels to detectable residues over 3 years.
  • Diphacinone is a greater threat of secondary poisoning to mammals than brodifacoum.
  • Strandings of whales, some hemorrhaging, occurred within 60 days following anticoagulant bombardment.
  • Unusual mass strandings of hemorrhaging dolphins occurred in San Diego and Hawaii years after anticoagulant bombardment.
  • There is very little known about the fate of anticoagulant residues in the oceans.

Our knowledge of contamination of the food web caused by rodenticide drops on islands is limited because monitoring is usually short-term and frequently done by the same contractors who implemented the project, with little motivation to report the extent or persistence of contamination.  For the same reasons, we have limited knowledge of how successful the projects are.

Track record of island eradications

About 1,200 island eradications have been done all over the world over the last 30 years.  Our evaluation of the proposed project on the Farallon Islands is based on the success or failure of those projects.

The aerial application of rodenticide to kill rats on Anacapa Island in 2001-2002 was the first of its kind in North America.  The project was also unique because it was complicated by the need to spare a population of endemic native deer mice on Anacapa.  Over 1,000 native mice were captured before the aerial application of rodenticide and released back on the island after the poison was no longer effective.  Although post-project monitoring reported successful eradication of rats, they were not confident that all of the mice that were left on the island had been killed. (1)

Attempts to eradicate mice have been consistently less successful than attempts to eradicate rats.  A study of 139 attempted eradications of animals on 107 Mediterranean islands in eight countries found that eradication projects targeted 13 mammal species. The black rat was the target of over 75% of the known attempted eradications in the Mediterranean Basin. The most widely used technique was poisoning (77% of all eradications), followed by trapping (15%) and hunting (4%).  Techniques were largely target-specific.

The average failure rate of the projects was about 11%, but success was defined only as the death of animals living on the islands at the time of the project. However, this percentage varied according to species. The failure rate of house mouse eradication was 75%. Reinvasion occurred after 15% of eradications initially considered successful. (2)

Island eradications considered initially successful, are often failures in the long run.  A recent visitor to Anacapa Island has reported seeing two dead rodents as her escorted group was leaving the island. One was identified as a deer mouse. The other rodent was not identified. Have rats returned to Anacapa?  Are native deer mice still being killed by residues of rodenticide? (3)

The eradication of rats on Anacapa Island is relevant to the planned project on the Farallon Islands because rats were killed, but mice were saved.  Although the Anacapa project considered rats a threat to birds, it did not consider mice a problem.  Rats were killed, but mice were saved by trapping and removing them from the island before the rodenticide was dropped.  Mice on the Farallon Islands are not a threat to birds.  They will be killed only because they are non-native.

Mice are members of the food web

Mice on the Farallon Islands are as much a part of the food web as they are on Anacapa Island.  They are prey of the birds and they are mainly predators of vegetation.  On the Farallon Islands, mouse predation of vegetation is considered a problem, but on Anacapa Island it is not considered a problem.  On the Farallon Islands, the study of the diet of mice reports that mice also eat insects when vegetation becomes scarce in the fall.  (4)

The study of the mouse diet on the Farallons also reports that 63%-80% of the vegetation on the Farallons is non-native.  That’s why Roundup (glyphosate) has been used on the Farallon Islands every year since 1988.  Between 2001-2005, an average of 226 gallons of herbicide were used annually (5.4 gallons per acre per year), according to the annual report of the Farallon National Wildlife Refuge. (5)

I took this photo on Santa Cruz Island in 2010, while visiting with an escorted group.

The Farallon Islands have never been inhabited and there has been no public access to the islands for over 100 years.  Non-native plants were not brought to the Farallons by humans.  Their seeds were brought by birds in their stomachs, in their feathers, on their feet and by wind and ocean currents.  Non-native plants dominate vegetation on the Farallons partly because non-native plants are eaten by birds.  The plants are members of the food web and their eradication is depriving birds and other animals in the ecosystem of food.  If non-native plants were not being eradicated with herbicides, it probably would not be necessary for mice to eat insects, which are not their preferred food.  We can safely assume that herbicides are harmful to the animals that consume plants that have been sprayed. (6)

Consequences of fiddling with the food web

There were also feral cats on the Farallons before they were killed.  Predictably, the population of mice increased after the cats were killed.  When 6,000 feral pigs were killed by sharp shooters on Santa Cruz Island, Golden Eagles substituted for that plentiful food source by preying on the rare, native Channel Island Fox.  Golden Eagles were captured and relocated to the mainland.  The fox population was restored to the island by a captive breeding problem.  The same could be done on the Farallons to eliminate the only known threat to ashy storm petrels.  The small population (approximately 6-10) of burrowing owls that are the only known predators of the petrels could be trapped and removed to the mainland as the Golden Eagles were on Santa Cruz Island.

Restoration plans for any ecosystem should begin with a thorough analysis of the food web.  Plucking single species of plants and animals out of complex ecosystems without understanding their role in the food web results in unintended and harmful consequences.

The Farallons project is based on mistaken assumptions

The Farallons project is based on the mistaken assumptions of invasion biology.  Most of the vegetation on the island is being killed with herbicide because it is non-native.  The vegetation is clearly essential to all the animals living on the island, but invasion biology asks us to believe that it is not, solely because it is non-native.  If the mice are killed on the island, it is only because they are non-native, not because they are harmful to birds.  They are an important source of food for the birds, but invasion biology asks us to believe they are not, solely because they are not native.  These assumptions are wrong, yet 50 years of nativist ideology still has a death grip on our public lands. 

This deadly dogma is losing its grip, but apparently too slowly to prevent the destruction of the food web on the Farallon Islands.  I always attend the conferences of the California Invasive Plant Council (Cal-IPC) and the California Native Plant Society (CNPS) to give native plant advocates every opportunity to convince me of their ideology.  Consistently, I find more support for my contrarian viewpoint than I do for invasion biology.  A presentation about the salt marsh harvest mouse at the Cal-IPC conference in October 2023, is an example.

California Department of Fish and Wildlife collaborated with UC Davis to study the food preferences of salt marsh harvest mouse (SMHM), an endangered native animal that lives in the wetlands of the San Francisco Bay. It has always been presumed to be entirely dependent on native pickleweed for food and habitat. The legally mandated recovery plan is based on that mistaken assumption.

Presentation to California Invasive Plant Council conference in October 2023

The study reported to Cal-IPC shows clearly that SMHM is NOT dependent on pickleweed for either food or habitat. SMHM is an extreme omnivore. SMHM ate 39 species of native and non-native plants as well as insects in empirical trials. In fact, it ate EVERY plant it was offered. A fecal study of SMHM living in the wild confirmed that finding. Fecal analysis found SMHM had eaten 48 native and non-native plant genera as well as some insects.

Presentation to California Invasive Plant Council conference in October 2023

SMHM have no preference for native plants for either food or nesting habitat. The most SMHM’s captured in the study were found where there was less than 10% pickleweed.

This was an absurdly simple experiment in which SMHM were captured and fed a variety of plants. It could have been done by anyone with little knowledge or fancy equipment. Why does this foolish mistake, caused by nativist bias, matter? Because “restoration” projects all around the San Francisco Bay have been eradicating non-native plants, claiming it would benefit the endangered SMHM.

For example, the spartina eradication project has been hunting for and poisoning hybrid spartina marsh grass for nearly 20 years, as well as planting pickleweed for SMHM. Since herbicides are used to kill non-native plants before pickleweed is planted, there’s little doubt that SMHM populations were harmed by the eradication of their food and shelter, if not directly harmed by the pesticides that are used.

Nativism in the natural world is not benefiting wildlife. Rather it seems to benefit only the army of “restorationists” who earn their living killing harmless plants and animals.  As long as they continue to receive public funding for their projects, they have job security because they have spent over 20 years trying to do something that cannot be done. Evolution moves inexorably forward. The puny efforts of humans to regress landscapes to arbitrarily selected historical standards cannot change the forward trajectory.

There were two presentations about difficulties with native plant restorations on Anacapa and Santa Rosa Islands at the CNPS conference in October 2022.  More than 20 years after non-native iceplant, rabbits, and rats were killed on Anacapa, native flora and fauna are still described as degraded, “Due to the cumulative and severe impacts to the soil and native seedbank, native vegetation communities have not recovered on their own…”  On Santa Rosa Island the “restoration” community has installed artificial fog fences to replicate a historical cloud forest to improve survival of native chaparral plants. (7)

Alternatives to rodenticide drop on Farallon Islands

It is not necessary to kill mice on the Farallon Islands because they are not harmful to birds.  If non-native vegetation weren’t killed with herbicides, there would probably be enough vegetation for omnivorous house mice as well as birds.  Both mice and vegetation are being killed only because they are non-native.  If the nativist ideology were removed from the agenda, dumping rodenticides on mice and herbicides on non-native vegetation would not be necessary.

If the protection of ashy storm petrels really were the goal of the proposed project on the Farallon Islands, the most obvious solution would be to remove the small population of burrowing owls that are the only known predators of the petrels.  Keep in mind that ashy storm petrels are not considered threatened or endangered and that two applications for protected status have been denied. (8)

There is a non-lethal alternative to reducing populations of rodents using rodenticides that kill non-target birds and other animals.  Academic scientists at Arizona State University have developed birth control for rodents that can be used on the Farallons to reduce the population of mice.  (WISDOM Good Works)

In Summary

Killing house mice on the Farallon Islands with rodenticide is unnecessary and will be harmful to the ecosystem and its inhabitants because:

  • Aerial dropping 1.5 tons of rodenticide will poison the entire ecosystem, killing hundreds of non-target birds and marine animals.
  • House mice on the Farallon Islands do not need to be killed because they are food for birds and they are harmless.
  • If burrowing owls are killing nestlings of ashy storm petrels, they could be removed and relocated.
  • The nearly 40-year attempt to kill non-native vegetation with herbicide should be stopped because the vegetation is a vital element in the food web of the Farallon Islands.

Happy Holidays and thank you for your readership.

boesch-contamination-of-marine-mammals-by-rodenticide-2Download
  1. https://www.cambridge.org/core/journals/oryx/article/eradication-of-black-rats-rattus-rattus-from-anacapa-island/F1E46767D0EEC9A6357D414DD84ABE28
  2. https://onlinelibrary.wiley.com/doi/abs/10.1111/mam.12190
  3. https://myricopia.com/2023/11/21/anacapa-island-conservation/
  4. https://www.biorxiv.org/content/10.1101/2022.02.23.481645v1.full
  5. https://drive.google.com/file/d/1XoPcS104SeOUIyfbPT_NbardctNyWAgs/view
  6. https://www.nrdc.org/sites/default/files/opinion-glyphosate-20220617.pdf “As to ecological risk, it finds potential risks to animals and plants and ‘requires’ mitigation in light of those risks, laying out specific language for glyphosate product labels.”
  7. https://www.nps.gov/chis/learn/nature/cloud-forest.htm
  8. https://www.endangeredspecieslawandpolicy.com/u-s-fish-and-wildlife-service-denies-endangered-species-act-protection-for-ashy-storm-petrel

https://wisdomgoodworks.org/2023/10/611/

Redefining Ecological Restoration

“Urban Jungle is breathtaking in its scope, both geographic and temporal… I can say I probably learned more per page in Urban Jungle than in any other book I have read at all recently.” –Professor Art Shapiro

As climate change makes many places uninhabitable, there is a new urgency to restore natural habitats damaged by human activities. 

After a lengthy and contentious battle, the European Union narrowly voted to make a commitment to restore 20% of nature areas on land and sea within their borders.  Farmers were the primary opposition to making this commitment, claiming it would severely reduce their ability to produce sufficient food.  6,000 scientists from several countries disagreed:  “They argued that in the long term, it was climate change and nature degradation that constituted the highest threat, and that the proposed policy would ensure sustainable food production.” (1)

The Biden administration has issued an executive order to conserve 30% of US lands and oceans by 2030.  This 30X30 commitment has been funded by the State of California and is in the early stages of implementation.  In the US, the commitment to “restore” land is often interpreted as a commitment to destroy non-native species with pesticides with the goal of restoring native plants and animals. 

“Restoration” could mean something entirely different and a recently published book, Urban Jungle:  The History and Future of Nature in the City, invites us to redefine restoration in a very different way.  In a nutshell, Urban Jungle proposes to let nature heal itself without a preconceived goal to replicate historical landscapes that aren’t adapted to the climate and the challenging conditions of the urban environment.  Left to its own devices, nature creates novel ecosystems, plant communities that are biodiverse and self-sustaining. 

World War II created a case study of novel ecosystems

When World War II ended in 1945, the Potsdam Agreement determined that Germany would be occupied by the allies that won the war:  United States, United Kingdom, France, and Soviet Union.  The map of post-war Germany (see below) shows the division of Germany among the allies.  The white portion of the map was administered by the Western Allies and the gray portion of the map by the Soviet Union.  Berlin (in red) was deep in Soviet controlled East Germany and was likewise divided into East and West Berlin.  The Soviet Union did whatever it could to isolate West Berlin by restricting access routes to West Berlin and ultimately building a wall around it in 1961.

Source: https://en.wikipedia.org/wiki/GNU_Free_Documentation_License

Berlin was heavily bombed during the war and was largely a pile of rubble at the end of the war.  While other European cities were able to clear the rubble within a few years, West Berlin could not because the Soviets would not let them dispose of rubble outside city limits. 

The physical isolation of West Berlin and the restricted access of the population to the countryside turned West Berlin into an ecological island.  Scientists in West Berlin, with few other opportunities to pursue their interests in botany and ecology, studied and recorded the transition of many tons of building rubble into novel ecosystems populated by whatever plants could find their way there and survive the challenging conditions.  West Berlin was physically isolated from 1945 until the reunification of West and East Germany in 1990, creating a unique opportunity to study natural succession in an urban setting when nature is left alone for nearly 50 years. 

One of the first pioneer plants in West Berlin arrived with the Ukrainian army in the hay brought to feed their horses.  Salsola collina, a tumbleweed, is native to southern Russia and central Asia.  Its arrival was a preview of what was to come, a landscape that would be radically different from the pre-urban landscape.  The plants best adapted to the harsh conditions of the ruined city were hardy non-native species.

Non-native plants that thrived in West Berlin were more tolerant of higher temperatures in an urban setting, where hard surfaces absorb more solar radiation, buildings block the wind, and greater pollution traps heat.  This is known as the heat island effect.  By the 1960s, the temperature in Berlin was on average over 4⁰F higher than the surrounding countryside.

Südgelände Nature Park in Berlin was a railway yard that was abandoned in 1952 as a result of the division of East and West Berlin.  By 1984 there were 334 ferns and flowering plants and many animals, birds, and insects living in the park.  It is a novel ecosystem that was shaped by human activities then left to natural processes. It remains as a nature park today because the people of Berlin fought against developing it into a train station again. They had come to love its wild beauty during their long confinement during the Cold War and they weren’t willing to give it up. Source: Südgelände Natur Park

The naturally evolving novel ecosystems in West Berlin were also surprisingly biodiverse.  Where natural succession was allowed to occur over many years, 140 different plant species and 200 insect species were found in the 21st Century.  In nearby Tiergarten Park, which is carefully maintained as a park, only one-quarter as many insects were found in an area of comparable size.  By the end of the 20th century, 1,392 naturalized plant species were growing in Berlin, compared to 822 in the 18th century. 

21st Century equivalent to World War II

Climate change is the 21st Century equivalent of World War II in its potential to cause death and destruction.  Climate change will create similar requirements to restore environments that are destroyed.  Urban settings will be particularly vulnerable to the consequences of climate change because they are population centers and they are already compromised by urbanization. 

Tidal estuaries and wetlands are one of many ecosystems that are threatened by climate change, as sea-levels rise in a warming climate and intensity and frequency of storms increases flooding.  These threats are greater in urbanized areas because most of our largest cities were built on coastlines and rivers at a time when transportation and shipping was easier by water than by land.

Historically, cities were protected from storms by surrounding marshlands that filtered and cleansed runoff from the land, polluted by human waste. But as cities grew, marshlands were often destroyed to create more land.  In many cases, the landfill was composed of the garbage produced by city-dwellers. 

The closure of urban garbage landfills and the restoration of wetlands to buffer the city from the rising sea and extreme weather events is another opportunity to redefine restoration as a natural process that uses the healing powers of nature.  Urban Jungle uses Fresh Kills Landfill in New York City as an example of restoring nature by leaving it alone.

Historical map of Freshkills Park in 1912, before it was a landfill garbage dump. Source: https://www.nycgovparks.org/park-features/freshkills-park/about-the-site

Fresh Kills was a tidal estuary and marshland on the west side of Staten Island in New York City.  It was opened as a landfill to accept residential garbage in 1948.  By 1986 it had reached peak volume, receiving 26,000 tons of residential garbage per day.  When it was closed in March 2001, the garbage was from 90 to 225 feet tall, weighing 150 million short tons.  It was reopened in September 2001 to accept about one-third of the rubble from the collapse of the World Trade Center on September 11, 2001.  It was the largest garbage landfill in the world when it finally closed.

Fresh Kills Landfill is now in a 30-year process of being restored as a park, renamed Freshkills Park.  The garbage was capped (see below) and methane produced by the decomposing garbage is being captured and used to heat about 22,000 homes on Staten Island. 

Source: https://www.nycgovparks.org/park-features/freshkills-park/about-the-site

The productive wetland ecosystem that was destroyed by the landfill cannot be restored.  Instead, a new ecosystem will slowly emerge on top of the toxic garbage.  The process began by seeding the slopes of garbage with fast-growing plants that were then plowed repeatedly back into the soil to add organic matter.  Then tough native grassland species were planted to provide habitat for initial colonizers, such as insects, small mammals and birds.  Now that basic conditions for life have been established, what happens next is in the hands of nature:  “Freshkills Park will be reclaimed by whatever species are attracted to the foundation of grasses.  Nature will do the bulk of the work, not human beings.  Biodiversity will steadily build as winds and birds bring seeds to the site.  This process of spontaneous successional growth is how nature rebounds from natural disasters such as forest fires, earthquakes, volcanic activity and climate upheaval.  Only in the case of Freshkills Park, the disaster was humanmade.” (2)

View of Downtown Manhattan from Freshkills Park. Licensed by Creative Commons

Getting off the pesticide treadmill

Allowing nature to heal the places humans have damaged is also an opportunity to get off the pesticide treadmill.  The natural process of succession does not require the use of herbicides to eradicate non-native plants that arrive naturally on the wind, in water currents, and in the stomachs of animals and birds.  When all plants are welcome, there is no need for herbicides and there is more biodiversity that supports more animals and is more resilient as the climate changes in unpredictable ways. 

In a place like Freshkills Park, it would defeat the purpose of turning a toxic landfill into a park public to use herbicides, insecticides, or rodenticides.  New York City banned the use of most pesticides in its public parks in 2021.   

In 2019, France banned the use of glyphosate-based herbicides for non-agricultural use.  The French city of Blois imposed the ban before the national ban was adopted:  “A study published in 2019 found more than 300 species of urban plants sprouting out of the pavements of the French city of Blois, which had recently phased out glyphosate weedkiller.”  (2)

Allowing nature to “manage” our public parks, makes them safer for us and for wildlife as well as more biodiverse than human management that wages a never-ending war on so-called “invasive” plants. There are more bees and bee species in cities than in surrounding countryside because there is more available food in its diverse vegetation:  “Analysis of honey from a bee in Boston, Massachusetts, found it had pollen taken from 411 different species of plants; nearby country honey contained traces from just eighty-two plants.  Cities are islands of biodiversity compared to rural monocultures, with a bigger and more diverse source of nectar even than nature reserves and forests…”  (2)

The takeaway message

Successful restoration of damaged land will take these facts into consideration:

  • Many hardy non-native plants are better adapted to challenging urban conditions than native plants: “If native plants can’t hack it in the metropolis, their place should be taken by specialist species drawn from around the world that find niches in the various microclimates of the concrete jungle.”  (2)
  • A diverse landscape of native and non-native plants is more resilient in a changing, variable, and unpredictable climate.
  • Novel ecosystems created by natural succession are more biodiverse than their historical predecessors.
  • When pesticides are used to kill non-native plants, disturbed land is damaged further and is even less likely to support a native landscape.  Killing non-native plants with herbicide also reduces biodiversity. 

(1) https://www.nytimes.com/2023/07/12/climate/europe-nature-restoration-law.html?searchResultPosition=1

(2) Urban Jungle:  The History and Future of Nature in the City, Ben Wilson, Doubleday, 2023

Going Toe to Toe with Doug Tallamy

In June 2023, Washington Post published an opinion piece advocating for the use of herbicides to kill non-native plants, in which Doug Tallamy was quoted as saying that spraying herbicide on non-native plants is “chemotherapy,”  equating non-native plants with cancer and pesticides with medical therapy.  Tallamy. and more broadly his viewpoint, received some blowback from Conservation Sense and Nonsense and others.

Thomas Christopher and Doug Tallamy collaborate on their shared mission of promoting the use of native plants and the closely related goal of eradicating non-native plants they consider a threat to native plants and insects. In October 2023, Tom Christopher (TC) gave Doug Tallamy (DT) an opportunity to respond to criticism of native plant dogma on his Growing Greener podcast that is available HERE.  Christopher also invited listeners to send him feedback on the podcast.  Professor Art Shapiro, whose work was central to the interview, has responded separately and his response is available as a footnote.  Conservation Sense and Nonsense (CSN) sent Christopher an email, which I hope he shared with Tallamy.  The following is an excerpt from that email. 

Hi Tom, Thanks for the air time for opposition to eradicating non-native plants in your interview with Doug Tallamy and for this opportunity to respond.  I’m flattered that criticism of native plant dogma has attracted some attention on the East Coast.  I’ve transcribed most of your interview with Doug Tallamy as best I can and provided some feedback to Tallamy’s viewpoint.  I sent Art Shapiro the podcast and he has responded separately.

TC:  Some people say that non-native plants are just as effective as natives in supporting food webs.  For example, buddleia that is spreading throughout the East and West is used by butterflies.

CSN:  Buddleia davidii is on California’s list of invasive plants, but it is not considered invasive in California.  It was put on California’s list because it is considered invasive elsewhere, making the point that invasive plant behavior varies depending on local conditions, such as climate.  Sweeping generalizations about invasiveness are rarely accurate. If gardeners are concerned about the potential for invasive behavior, they can plant a cultivar of buddleia that does not reproduce. 

DT:  We shouldn’t call all insects pollinators.  Just because an insect visits a flower for nectar doesn’t mean it’s pollinating that flower.  There are more visitors to flowers than there are pollinators.  Butterflies visiting buddleia are just there to sip nectar.

Euphydryas chalcedona
Variable checkerspot. Photo by Roger Hall

CSN:  Buddleia davidii is native to Central China.  Non-native buddleia is used by a butterfly species that is native to California and other states in the Western US.

The first actual observation of checkerspot butterflies breeding spontaneously and successfully on buddleia was in Mariposa County, California in the Sierra Nevada foothills.  Checkerspot bred there successfully on buddleia in 2005 and in subsequent years.  This colony of checkerspot on buddleia was reported in 2009:  “We conclude that buddleia davidii [and other species of buddleia] represents yet another exotic plant adopted as a larval host by a native California butterfly and that other members of the genus may also be used as the opportunity arises.” (1)

In 2017, a gardener in Mendocino County, California also reported the use of buddleia as the host plant of checkerspot:  “By now I am questioning how it was that butterfly larvae were using my butterfly bush as a host plant, completely against everything I’d ever heard. How was this possible? I emailed Art Shapiro, a very well-known butterfly expert and author, sending him a pic. He wrote back to confirm they were butterfly larvae, but added, ‘These are not mourning cloak butterflies. They are checkerspots. And the only time I’m aware this has happened [like, ever, except one in a lab in 1940…] is in Mariposa County.’” (2)

Buddleia is available as the host plant of checkerspot butterflies with a native range from Alaska south along the Pacific Coast through California and Arizona to Baja California and Mexico; east to Montana, the Dakotas, Wyoming, Colorado, New Mexico.  This is a clear case of a widespread native butterfly choosing a non-native plant as its host. 

  1.  Arthur M. Shapiro and Katie Hertfelder, “Use of Buddleia as Host Plant by Euphydryas chalcedona in the Sierra Nevada foothills, California,” News of the Lepidopterists’ Society, Spring 2009
  2. http://plantwhateverbringsyoujoy.com/never-pull-up-and-discard-what-you-cannot-identify/

DT:  Most bees that people see in their gardens are honeybees that are there to get pollen and sometimes nectar.  These are generalist bees but specialist bees that require pollen from particular plants (always native plants) can’t be supported by those at all. 

Squash bee. USDA public domain

CSN:  Specialization of insects is exaggerated by Tallamy.  For example, he would probably call a squash bee a specialist.  As its name implies, its host plant is squash plants in the squash family, with 98 genera and 975 species.  The squash bee is considered an excellent pollinator of zucchini and butternut squash, both native to Central and South America.  However, they do not usually visit melon plants, according to Wikipedia.  Again, we are reminded to avoid broad generalizations when describing the complex and diverse natural world. 

Likewise, the native alkali bee is a particularly effective pollinator of alfalfa, which is native to the Mediterranean region. Alkali bees also pollinate members of the large legume family with over 16,000 species that are native all over the world.  If you are interested in such associations, you can find an exhaustive list of native butterflies and their many non-native host plants in Art Shapiro’s butterfly guide for Central California and the Bay Area.  It is not true that bees Tallamy considers “specialists” require pollen from only native plants.

DT:  Sometimes butterflies adopt a new host plant as a caterpillar host.  For example, black swallowtail butterflies caterpillars eat carrots or parsley or dill.  What’s going on?   There are two different kind of hosts:  1) The caterpillar has not adopted a new host at all because it was already adapted to that particular host.  2) Actual host switching from one plant to another is very rare.  It happens on a time-scale of thousands of years.  It requires a mutation or an adaptation to chemical defenses of new host plants.

CSN:  Tallamy tries to make a distinction to avoid acknowledging that insects make use of introduced plants because they are chemically similar to the native plants they have used in the past, which in some cases are no longer available. The butterfly has, in fact, adopted a new host, a plant that wasn’t there before and is now hosting the caterpillar. There are many cases of rapid evolution that enable such transitions, but both cases are clearly transitions from native to non-native plants.  If the original native host is still available, it isn’t necessarily abandoned in favor of a non-native.  Such transitions are useful because they increase the population of available insect hosts and are essential if the original native host is no longer available.

TC:  Pushback from California cites research of Professor Art Shapiro reporting that spontaneous spread of non-native plants has benefited native butterflies.  He reports that 82 of 236 California native butterfly species (34%) are laying their eggs on introduced plant taxa, so caterpillars feed on them and many more butterflies use introduced plants as nectary sources.

DT:  Great!  These are host range expansions.  Agriculture in California has eliminated the host plants of a lot of butterflies and it’s a good thing we had close relatives of natives so butterflies could expand their host range and use them.  But if 34% of native butterflies are using introduced plants that means 66% are not.  If all plants were introduced, we would lose 66% of butterflies in California.  This is not the direction I want to go.  I would choose 60% rather than 34%.

CSN:  Christopher and Tallamy seem to have read one sentence in the abstract of Shapiro’s study without reading subsequent sentences: “Interactions with introduced plant taxa are not distributed evenly among butterfly species. Alpine and desert butterflies interact with relatively few introduced plants because few exotic plant species have reached and successfully colonized these habitats. Other California butterfly species are specialists on particular plant families or genera with no exotic representatives in California and have thus far failed to recognize any introduced plants as potential foodplants. Some California butterflies have expanded their geographic ranges and/or extended their flight seasons by feeding on exotic plants.”  In other words, where there are more introduced plants and some are closely related to native plant hosts, more native butterflies use introduced plants.   

TC:  What do you say to the claims that introduced plants stay greener longer than native plants adapted to wet or dry seasons so that introduced plants give rise to extra generations of caterpillars?

DT:  This is only true if caterpillars can use those plants and in host range expansions they can.  Shapiro is also right about extending availability of nectar.  For example, monarchs that migrate need forage along the way.  The minus is that we’ve been so hard on native flora.  These insects were doing just fine before we brought in non-native plants.  It’s a Band-Aid we’re putting on an environment that has been ravaged by taking out native species that were here before.  Let’s put native species back too.

CSN:  The claim that non-native plants are driving native plants to extirpation or extinction goes to the heart of the controversy.  Native plant advocates believe that accusation, although there is little evidence to support it.  The greatest threat to native plants and insects is habitat loss, particularly converting wildlands to agricultural fields.  The second greatest threat is the pesticides that are used by agriculture.  Remember that Tallamy is an enthusiastic promoter of herbicides to eradicate non-native plants.  He calls it “chemotherapy” in a recent opinion column in the Washington Post.  Pesticides kill both plants and the animals that feed on them, they are anathema to biodiversity and the food web that Tallamy believes he is supporting. 

Marcel Rejmanek (UC Davis) is the author of the most recent report on plant extinctions in California, published in 2017.  At that time there were 13 plant species and 17 sub-species native to California known to be globally extinct and another 30 species and sub-species extirpated in California but still found in other states.  Over half the globally extinct taxa were reported as extinct over 100 years ago.  Although grassland in California had been converted to Mediterranean annual grasses by grazing domesticated animals decades before then, most of the plants now designated as “invasive” in California were not widespread over 100 years ago.

Most of the globally extinct plant species had very small ranges and small populations.  The smaller the population, the greater the chances of extinction.  Most of the globally extinct plants were originally present in lowlands where most of the human population and habitat destruction are concentrated. Although there are many rare plants at higher altitudes, few are extinct.  Plants limited to special habitats, like wetlands, seem to be more vulnerable to extinction. The primary drivers of plant extinction in California are agriculture, urbanization and development in general.  Non-native plants are the innocent bystanders to disturbance.

“Invasive species” are mentioned only once in the inventory of extinct plants published by California Native Plant Society and only in combination with several other factors. However, the identity of this “invasive species” is not clear.  Rejmanek suggests that the “invasive species” rating refers to animal “invasions” by predators and grazers.  He says, “Indeed, one needs quite a bit of imagination to predict that any native plant species may be driven to extinction by invasive plants per se.” (Marcel Rejmanek, “Vascular plant extinctions in California: A critical assessment,” Diversity and Distributions, Journal of Conservation Biogeography, 2017)

TC:  90% of all insect species are specialists that have evolved in concert with only one or a few plant lineages.  How can they cope with the loss of native plants?

DT:  Native plants are adapting in evolutionary time.  Specialization is a continuum.  Few insects are confined to a single plant species, some are confined to one or two genera, and others are confined to one or two families of plants.  But if you are looking at the number of plants available to them, only about 7% of plants they are adapted to are available to them.   93% of available plants are not viable hosts for insects.  Everything is a specialist on one level of another.

CSN:  That sounds like an argument for a diverse garden, with many plant species that offer more food sources for insects.  That doesn’t seem a sound argument for eradicating non-native plants. 

TC:  I understand that some native plants are more useful to insects than others?

DT:  These are the keystone species.  Many native plants don’t support insects because plants are well-defended against them.  Keystone species are making most of the food for the food web.  Just 14% of native plants across the country are making 90% of food that drive the food web.  86% of the native plants are not driving the food web.  Insect food comes from the big producers, like oaks, black cherries, hickories, and birches.

CSN:  That is a mind-boggling admission!!  Earlier Tallamy complained that non-native plants are hosting only 34% of butterflies in California.  Now he says that only 14% of native plants are useful to insects.  He asks home gardeners to plant only native plants as well as limit our plantings to a small subset of native plants. 

Tallamy’s ideology is antithetical to the goal of biodiversity, which could be the salvation of ecosystems in a changing climate. Since we can’t predict the climate of the future, biodiversity provides more evolutionary options, which increases the chances that some species will survive. Tallamy asks us to put a few eggs in the huge basket of our ecosystems, reducing their ability to survive the challenges of our changing climate. 

For example, in Oakland, California, where I live, there were approximately 10 species of native trees prior to settlement.  In 1993, there were 350 tree species in Oakland. (David Nowak, “Historical vegetation change in Oakland and its implications for urban forest management,” Journal of Arboriculture, September 1993)  The recently published draft of Oakland’s Urban Forest Plan reports that there are now over 500 tree species in Oakland.  I can’t fathom why Oakland would want to limit the planting of trees to only 10 native species. 

I agree with Tallamy that many native plants are not useful to insects.  I attend the annual conference of California Invasive Plant Council to give native plant advocates every opportunity to convince me of their viewpoint.  At the most recent conference at the end of October, Corey Shake of Point Blue Conservation made a presentation about his project to “Evaluate native bee preference for common native and exotic plants.” 

He designed 16 hedgerows around agricultural fields in Yolo County to determine if native bees have a preference for native plants or exotic plants, by controlling for availability of native plants compared to exotic plants.  Here is his abstract:

“Farm edge restoration monitoring in Sacramento Valley highlights native bee use of some exotic plant floral resources. Corey Shake. Point Blue Conservation Science. cshake@pointblue.org

“Research of native bee preference for native versus exotic plant floral resources in California’s Sacramento Valley has shown mixed results. No studies have demonstrated a preference for exotic plants by native bees there, but some have highlighted the importance of exotic plant floral resources in plant-pollinator networks and expressed concern that rapid removal of exotic plants without restoring native plant populations could have negative impacts on native bees. We have been collecting native bee flower visitation, plant species, and floral abundance data on 16 farm edge restoration projects in Yolo County, California since 2019, which will allow us to assess bee preferences for some key native and exotic plants relative to their floral abundance. In our preliminary analysis, we see some important trends: (1) relative to their floral abundance in our plots, some native plant species are more frequently visited by native bees than other native plants that are infrequently or rarely visited, and (2) there is significant native bee visitation to some exotic plants relative to their floral abundance. We will further evaluate these data as well as our butterfly diversity and abundance data to provide plant-species specific insights to restoration practitioners and weed management specialists to help them reduce harmful impacts to native pollinators when executing restoration projects and managing weeds.” 

In other words, not all species of native plants are useful to native bees and some species of non-native plant species are useful to native bees.  Tallamy’s sweeping generalizations about the usefulness of native plants to insects are not supported by empirical or field studies.  Although the characteristics of plants vary widely, the variation is unrelated to the national origins of plants. 

From Micro to Macro Perspective

I recognize my voice in the questions Tom Christopher asked of Doug Tallamy, as well as Art Shapiro’s.  Speaking for myself, not for Art, this interview misses the point of my criticism of native plant ideology.  I like native plants as much as I like any plant and I encourage everyone to plant whatever they prefer.  I only object to the pointless destruction of harmless non-native plants that thrive because they are best adapted to the conditions where they have naturalized.  Non-native plants do particularly well in the wake of disturbance.  Where they have replaced native plants, the natives were destroyed by disturbance, not by the hardy non-native plants that can tolerate disturbance. Non-native plants are a symptom of change, not the cause. 

I object to destructive eradication projects because they poison the soil with herbicides, making it even less likely that non-native plants will be replaced by fragile native plants.  I object to the loss of biodiversity which is a hedge against extinction in a rapidly changing climate.  We don’t know which plants will be capable of surviving in the changed climate.  We should not be taking cards out of the deck while we gamble with the future of the environment and everything that lives in it.

Unfortunately, native plant advocates take offense when anything positive is said about introduced plants.  A positive statement about a non-native is routinely interpreted as a negative statement about native plants.  It shouldn’t be.  The emphasis on the negative assessment of introduced plants results in harmful land management decisions.  The pros and cons of all plants should be considered before we condemn non-natives with a death sentence.  Like our justice system for human society, all plants should be presumed innocent until proven guilty.

Thanks again for airing this debate on your podcast. I hope you will forward my email to Doug Tallamy

Webmaster, Conservation Sense and Nonsense

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Gardening with the help of nature

Juliet Stromberg is a plant ecologist who specialized in wetland and riparian ecosystems of the American Southwest.  Her friends call her Julie and I will presume to do the same.  She has retired from her position at Arizona State University, but her husband, Matt Chew, is still teaching ecology from a historical perspective at ASU.  He is very much her partner in their 20-year project to restore 4-acres of dead citrus grove and an 80-year old Spanish colonial house, long abandoned and derelict.  The property came with water rights, without which their project would not have been possible.

In her recently published book, Bringing Home the Wild:  A Riparian Garden in a Southwest City, Julie tells us how she and her partner transformed—with the help of natural processes–this dead patch of land in South Phoenix, Arizona into the oasis that it is today.  The first step was to restore the irrigation system, which immediately brought much of the dormant seed bank back to life. 

Julie & Matt’s garden is in the center of this aerial view

Using the riparian vegetation of the Salt River—the source of their water—as her reference, she chose a half-dozen tree species as the foundation of their garden, such as Fremont cottonwood, Gooding’s willow, and velvet mesquite.  Twenty years later, there are now 300 trees, sheltering a community of plants and animals.  How did they get there? 

The seeds of some trees such as blue elderberry and mulberry were brought from neighboring gardens by birds and small animals. Julie and Matt have seen 157 species of birds in their garden, so we can assume birds have done some of the planting.  The seeds of some plants are aerodynamically shaped and were blown in by the wind, adding to the diversity of the garden.

Tropical milkweed seeds ready to be launched by the wind from a neighbor’s front yard.  Conservation Sense and Nonsense, Oakland, CA, October 2023

Many of the trees are American in origin, but others are not.  Regardless of the method of dispersal, most introductions are welcome in Julie’s garden. She spares her readers the tedious recitation of which plants are considered native and which are not.  The Southwestern desert is not an ecosystem with which I am familiar.  I was glad to have a tour of Julie’s garden without irrelevant information about the nationality of every plant.  For the same reason, I like to travel in distant places where I can’t distinguish natives from non-natives.  Everything looks great to me and nothing brings me down more than a guide who wants to inform us of what “belongs” and what doesn’t. 

Julie and Matt also planted a fruit orchard and a vegetable garden that bring more birds, insects, and animals to the garden as well as providing food for their table. Eating the fruits of our labors in the garden deepens our respect for what plants do for us and establishes our working relationship with the land. 

Managing a wild garden

In keeping with Julie’s opinion that ecological restoration is a form of “glorified gardening,” she actively manages her garden.  A few plants that annoy members of her community of plants and animals—such as puncture vine and tumbleweed—are not welcome. 

When the delicate balance between predator and prey becomes unbalanced, some protective measures are necessary.  If coyotes and dogs can’t keep up with the rabbit population, it’s sometimes necessary to put vulnerable plants into cages to protect them.  The root balls of some plants are covered in wire mesh to protect them from hungry gophers. 

Plants also assist in their own defense.  Where mesquite is grazed by cattle, the tree responds by growing longer thorns to repel the cattle.  When plants are attacked by plant-eating insects, some emit a toxin to render themselves inedible.  The scent of the chemical wafts to neighboring plants, alerting them to the arrival of predators.  These natural defenses are an important line of scientific inquiry that has potential to substitute nature-based solutions for synthetic chemicals. 

The population of roof rats in Julie’s home is kept in check with liquid birth control, lest they chew on electrical wires or build nests in car engines. 

Gardening with the help of friends

Julie’s is not a manicured garden, but it requires constant pruning to keep trails clear and provide light and space for plants to thrive. The annual scouring of the flood plain by spring floods is one of the natural processes that Julie and Matt could not use to restore their land because irrigation water is channelized and confined by concrete.  Julie has come to appreciate the flies and other insects who are the decomposing crew, helping to reduce the accumulation of debris in the absence of annual scouring floods.  Sixty-six species of flies assist with decomposition as well as pollination in Julie’s garden. 

Julie is happy to have coyotes in her garden, but her dogs disagree.  Violent and fatal confrontations between these closely related species required building a wall that confines dogs close to the house at night, while coyotes safely roam most of the garden. 

Dogs are an important part of Julie and Matt’s life.  Early in the book’s introduction Julie warns readers that they should put her book down “NOW!” if they don’t want to hear dog stories.  Julie has walked thousands of dogs in a nearby animal shelter.  In addition to her own 4 dogs, there are also occasional foster dogs who need to recover from traumatic experiences to be adoptable.  In Julie’s refuge, these traumatized dogs learn to trust again. 

Peaceful co-existence

Julie is a recovering academic scientist.  Before she retired, she felt that her focus on the accumulation of data needed for scientific analysis was causing her to lose track of the big picture.  She needed to stop and smell the flowers, so to speak. 

She received her graduate education during the heyday of invasion biology. Julie slowly shifted away from native purism based on her experiences in the field.  She has rejected that doctrine, and regrets teaching her students to fear “those who came from somewhere else.” 

Julie has a vivid memory of the first step she took on that journey to her gardening ethic of peaceful coexistence.  She had been instructed to pull tree tobacco from land along the Salt River that was being restored.  The nicotine in the plant was making her feel sick, which seemed to bring her to her senses.  She began to wonder what she was doing, “following orders to kill creatures she barely knew.” 

Fly on desert tobacco. Photo courtesy Juliet Stromberg

Part of Julie’s skepticism about such eradication projects is based on her understanding of how little we know.  She realizes that the harm done by non-native species is exaggerated and their benefits are underestimated.  Given the limits of our knowledge, we should be obligated to give introduced plants the benefit of the doubt before killing them.  She now appreciates the beauty of tree tobacco, which also feeds birds, fixes carbon, and stabilizes the soil.   Its seeds were naturally dispersed to Julie’s garden and tree tobacco is welcome there.

Imperatives imposed by climate change

Julie says, “The preoccupation with provenance diverts conservationists and gardeners from critical issues,” such as climate change, food security, and extinction (which, studies show, are not caused by introduced plants).  Living in the Southwest, Julie has a front row seat on climate change.  It’s always (within the context of our lifetime) been hot there, but now it is blisteringly hot during summer months.  She watches hummingbirds in her garden seek shelter in the shade, close to the irrigation drip.  She watches dogs panting, birds gasping for breath and plants wither and die in the heat.  And she knows that both native and non-native plants store carbon that would otherwise contribute to greenhouse gases causing climate change. Carbon storage varies according to certain plant characteristics, but those characteristics are unrelated to the nationality of plants. 

Those who insist on replicating the landscape that existed 200-400 years ago in America are depriving nature of the evolutionary opportunities that will enable survival.  We don’t know what life will be capable of living in the climate of the near-future.  Nature needs as many alternatives as possible to find the species that can survive.  Plants and animals are blameless in this struggle of survival of the fittest.  The least we can do is to get out of their way as natural selection finds the life that is adapted to the current and future climate.

Showing respect for nature

Julie does not use any pesticides in her garden….no herbicides, fungicide, or insecticide.  She is concerned about the pesticides used by her neighbor across the road who grows cotton.  She notices the blue cotton seeds scattered on the ground and surmises that they were coated in insecticide or herbicide that will infuse pesticide into the plant as it grows.  The poisoned seed can kill seed-eating birds and other animals and the plant itself will be poisonous as it grows.  The dust from the cotton field blows into her property when the field is plowed and after the cotton is harvested because no cover crops are grown to tamp down the dust and prevent the loss of carbon stored in the soil.  Julie can see firsthand the damage caused by industrial agriculture and is confirmed in her commitment to avoid using pesticides.

Julie shows her respect for everything living in her garden by her choice of pronouns to describe them:  “who” not “what,”  “she/her” not “it.”  She asks her readers to show the same respect for plants and animals, regardless of their nationality.  Avoiding the use of pesticides in our gardens is another way to show our respect for the plants and animals on which we depend, with the added benefit of not poisoning ourselves.

Thank you, Juliet Stromberg, for telling us about your garden and congratulations for what you have accomplished and learned from the experience of nurturing it back to life with the help of nature. 

Oakland’s revised Vegetation Management Plan is the compromise I hoped for

On September 1st, I told readers that Oakland would soon publish a revised Vegetation Management Plan to reduce fire hazards in Oakland by managing vegetation on 2,000 acres of city-owned property and 300 miles of roadside.  I also shared with readers my anxiety that the revised plan would be more destructive than the previous version of the plan in response to criticism of that version.    

The 4th revision of Oakland’s Vegetation Management Plan and its revised Draft Environmental Impact Report was published on September 20th.  These documents are available HERE.  There will be a public hearing about the plan by Oakland’s Planning Commission on November 1st.  The deadline for submitting written comments on the plan is November 4th.  Comments can be submitted by email DEIR-comments@oaklandvegmanagement.org or by mail to Montrose Environmental, attention Ken Schwarz, 1 Kaiser Plaza, Suite 340, Oakland CA 94612.

Update:  The deadline for commenting on the Vegetation Management Plan has been extended to Monday, November 6, 2023, at 5 PM.

The Oakland Planning Commission held a public hearing about the VMP on Wednesday, November 1, 2023.  There was no expressed opposition to the VMP at the hearing.  Representatives of Claremont Canyon Conservancy, North Hills Community Association, and Oakland Fire Safe Council spoke in support of the plan. 

One speaker said that Oakland Fire Department and the consultant who wrote the plan successfully “threaded the needle” that made agreement possible.  She also said that “of course, we wish all the eucalyptus were gone, but we understand that is expensive.”

All members of the Planning Commission expressed their admiration and support for the VMP.

Below is a map of the VMP project areas.  Figure 2.2 in the revised plan also shows detailed maps of roads in VMP project areas, with property ownership adjacent to roads indicated, which require different vegetation management standards.   

The authors of the plan have made it easy for you to read the revised version by underlining additions and striking out deletions.  If you have read earlier versions of the plan, you won’t need to read it all again, because revisions are minimal.  They are briefly summarized on page 1-2 of the plan:

“Expanded the Revised Draft VMP area to encompass the area from 30 feet to 100 feet of the edge of roadsides in the City’s VHFHSZ [Very High Fire Hazard Severity Zone] where dead and dying trees (as determined by a Certified Arborist, Licensed Forester, or Fire Safety Expert) are present on City owned property and could strike the road if they fell.

“Updated the vegetation management standards as follows:

  • Expanded the zone recommended for 3-inch maximum height of grasslands after treatment from 30 feet to 75 feet from habitable structures.
  • Clarified that, where feasible, horizontal crown spacing should adhere to the California Department of Forestry and Fire Protection’s (CAL FIRE’s) most recent defensible space standards (presently codified in Pub. Res. Code Section 4291).

“Updated treatment standards for eucalyptus stands to increase the trunk diameter of single-stem eucalyptus recommended for removal from 8 inches to 10 inches, and to recommend removal of trees that pose an unreasonable fire and/or life safety risk, based on the determination of a Certified Arborist, Licensed Forester, or Fire Safety Expert.

“Updated treatment standards for closed-cone pine-cypress stands to include removal of trees that pose an unreasonable fire and/or life safety risk, based on the determination of a Certified Arborist, Licensed Forester, or Fire Safety Expert.”

If you need a reminder of vegetation management standards in the previous version, you can find them on Table 2-4.  Basically, the VMP will thin trees and vegetation and remove dead trees and fire ladders to canopies in management areas. The most significant revision of those vegetation management standards is the expansion of clearance of dead and dying trees from 30-100 feet from the edge of 300 miles of roadsides on city-owned property. The management standards defined by the previous version were acceptable to me and the proposed revision of those standards are also acceptable to me. 

However, I am sorry to see that more eucalyptus will be removed because the diameter size standard for removal has been increased from 8 to 10 inches (circumference is greater than 31 inches).  The flammability of eucalyptus has been exaggerated by native plant advocates who want all non-native trees to be destroyed.  California’s native vegetation is fire adapted and fire dependent.  Many of our most prominent native plants—such as ceanothus and manzanita–will not germinate in the absence of fire.  The planned removal of isolated non-native trees within stands of native trees is unnecessary because it will not reduce fire hazards. The VMP should be a fire hazard reduction plan, NOT a native plant restoration.

Although I recognize that dead trees are important for the long-term health of forests because they provide food and habitat for insects and birds as well as recycle nutrients into the soil, we can’t indulge that preference in very high fire hazard zones in high-density population areas that are being treated by Oakland’s Vegetation Management Plan.  As always, we must set priorities and the public’s safety must be a high priority. 

Like most public policy, the revised Vegetation Management Plan is a compromise between two extremes.  One extreme wanted all non-native trees to be destroyed in the management areas as well as within 100 feet from the edge of 300 miles of roadside.  They also wanted Oakland to make a commitment to replace those trees with native vegetation.  The opposite extreme wanted no trees to be destroyed and no herbicides to be used to control vegetation or prevent destroyed trees from resprouting. 

The revised Vegetation Management Plan is the compromise I had hoped for.  Specifically, I had hoped that fire hazards could be reduced in Oakland without destroying more trees than necessary to mitigate fire hazards. The thinning strategy that the VMP proposes has been used successfully by the East Bay Regional Park District for over 10 years.  It leaves the canopy intact so the forest floor is shaded, which suppresses the growth of weeds and keeps the forest floor moist, which retards ignition.

I had hoped that herbicides would not be used in public parks, but did not achieve that goal. However, I am grateful that the revised plan makes many efforts to protect the public, their pets, wildlife and goats grazing in project areas from exposure to the herbicides that will be used.  (Improvements in these protections are described on pages 2-81, 3.3-29, 3.3-32)  There are also extensive new protections for monarch butterflies and a rare species of bee (see page 3.4-86). 

If your interests in the Vegetation Management Plan are different from mine, I urge you to read the plan and form your own opinion.  I hope you will be able to support the revision because it is going to be attacked by the same extreme interests that have prevented Oakland from adopting and implementing a fire hazard mitigation plan for over 7 years. Expressing our support might help to get the VMP over the finish line after years of delay caused by gridlock. I would welcome you to the middle ground that I occupy.  It’s lonely here in the middle.  We don’t have much of an audience above the noise made by the extremes, but we have the capacity to enable public policy to be made if we speak up in defense of compromise. If we want to reduce wildfire hazards in Oakland, we must compromise.

An Attempt to Legally Mandate Native Plants Throughout California Has Failed

This is a story of the influence of interest groups on the process of making new laws.  When Assembly Bill 1573 was introduced in February 2023, it seemed to be primarily a water-saving measure that would “eliminate the use of irrigation of nonfunctional turf” (turf that is not a recreational area or community space with foot traffic).  AB1573 also mandated that all new or renovated nonresidential areas install not less than 25% local native plants by 2026, 50% local native plants by 2030, and 75% local native plants by 2035.  It defined local native plants as “California indigenous plants to an area that have evolved and occur naturally in the Jepson Region associated with a specific California location.”

As AB1573 passed through legislative committees in the Assembly and the Senate it was amended six times (legislative history of AB1573 is available HERE.).  California Native Plant Society and its many allies pulled out all the stops to influence the legislation and ensure its passage.  Members of these advocacy organizations were asked at each juncture to contact their elected representative to urge them to pass this legal mandate requiring public and commercial properties to plant native plants.

The final revision of AB1573 occurred on September 1st, after consideration by the Senate Appropriations Committee.  The final revision made two significant changes:

  • The requirement for native plants in new and renovated landscapes on non-residential properties was lowered to 10%.
  • However, the definition of native plant was revised to include:  “a plant that is nonnative and noninvasive that provides pollinator benefits, and that is a low-water use plant, as determined by the Department of Water Resources and the Natural Resources Agency”  In other words, the final revision considers many non-native plants the functional equivalent of native plants.

On September 7, 2023, the authors of AB1573 asked that the bill be moved to the “inactive file.” They have given up.  Their bill has been so emasculated that they don’t see the point of continuing to try to pass it.  

Why did this attempt to legally mandate native plants fail?

There are probably many aspects of this story that I don’t know.  There were probably many private meetings and written communications that I’m not aware of.  I could probably learn about some of them by making a public records request, but I think I know enough of the story to relate it to my readers.  If you know more about the process than I do, please share it with us.

The first visible sign that AB1573 was in trouble was in June 2023, when the Associate Director of Plant California Alliance published an editorial about AB1573 in an agricultural newsletter, available HERE.  Plant California Alliance represents “California’s nursery industry. Our membership includes farmers, growers, urban agriculturists, wholesalers, retail garden centers, landscapers, garden suppliers, horticulturalists, as well as educators and researchers.”  This is an organization with horticultural knowledge and practical experience growing plants in California. The editorial explained why the goals of AB1573 are unrealistic and based on mistaken assumptions about California native plants:

  • There aren’t enough native plants available for sale to meet such a requirement. California Native Plant Society claims nursery sales are about 6% native, but two large wholesale nurseries estimate their stock is not more than 1% native. 
  • “…there is also the fundamental question of why a native plant mandate is included in a water conservation bill at all. Not all native plants are low water plants…Sometimes a non-native plant is a better choice when designing a drought resilient, low water garden.” California Water Service recommends:  “Plants that are adapted to long, dry summers and short, rainy winters are called “Mediterranean-zone” plants. These include plants that are native to California, as well as those that originated in southern Europe, South America, and other “Mediterranean” climates. These plants don’t need much water in the summer and have thrived in water-scarce conditions for thousands of years.”
  • “And, what about native plants’ impacts on fire? Unfortunately, some California native plants are not considered fire-resistant, and some are even considered fire prone. For example, FireSafe Marin has several California native plants on their list of fire-prone plants, including manzanita (Arctostaphylos), coyote brush (Baccharis spp.), California buckwheat (Erigonum fasciculatum), and California bay (Umbellularia californica).” Most wildfires in California occur in native chaparral and native conifer forests. When wildfires occur in residential neighborhoods, the homes themselves are the primary fuel for the fire. Everything burns in wind-driven fires, regardless of the native origins of plants.
NY Times reported that 150 homes burned in this wind-driven fire in San Diego in 2003, but the eucalyptus surrounding the neighborhood did not burn. NY Times photo

In August, tree advocacy organizations finally woke up to the implications of AB1573 for California’s urban forests when they realized that the definition of “native plant” also included native trees.  California Releaf and California Urban Forests Council asked their members to contact the Senate Appropriations Committee to ask that trees be explicitly exempted from the requirement for native plants on non-residential properties in California. 

Composition of California’s Urban Forest. Source: Californian’s Guide to the Trees Among Us

Only 9% of California’s urban forests are native to California. (1)  Pre-settlement San Francisco was virtually treeless.  One-third of San Francisco was barren sand dunes on its western edge.  San Francisco’s urban forest is now predominantly non-native and much of it is being destroyed to accommodate native plant restorations that require full sun. 

Birds-eye view of San Francisco in 1868

Non-native trees were planted in Oakland in the 19th century because there were few native trees: “Vegetation before urbanization in Oakland was dominated by grass, shrub, and marshlands that occupied approximately 98% of the area.” (2)  Non-native tree species in the East Bay are adapted to soil and microclimate conditions that are not suitable for native species.  Non-native annual grasses will replace Oakland’s urban forest in the hills, not native trees, if native plant advocates get the Vegetation Management Plan they have been fighting for for nearly 8 years.

A Learning Experience?

I would like to think that California’s policy makers learned something from the process of considering AB1573.  Do they have a better understanding of what grew in California in the past and therefore what is capable of growing in the future?

Probably not

Ironically, on the same day that AB1573 was withdrawn by its authors, the San Francisco Examiner published this article about a new initiative to plant more greenery in San Francisco, led by the California Academy of Sciences.  It’s an excellent idea, except that the leaders of this initiative equate greenery with native plants:  “He’s looking to introduce more native plants in The City, which will in turn attract more native insects and more native birds throughout San Francisco.”  Nature is not synonymous with native plants.  The scientific definition of biodiversity includes both native and non-native plants.  In fact, San Francisco’s Open Space Element of the General Plan also defines biodiversity as including both native and non-native plants. 

As much as I would like to hope that Californians have a more realistic goal for the future of California’s landscapes after watching the failure of AB1573, I don’t think I can. 

  1. Matt Ritter, A Californian’s Guide to the Trees Among Us, Heydey Books, 2016.
  2. David Nowak, “Historical vegetation change in Oakland and its implications for urban forest management,” Journal of Arboriculture, September 1993

Oakland’s Vegetation Management Plan Is Headed in a Destructive Direction

Oakland has been trying to adopt a vegetation management plan (VMP) to mitigate fire hazards since November 2016.  The plan has been drafted three times in 2018, 2019, and 2020 and a draft Environmental Impact Report was also published in 2020.  All three versions of the plan were acceptable to me and many others.  Every version would have removed dead trees and thinned non-native trees on 2,000 acres of public land and 300 miles of roadsides in Oakland, leaving the tree canopy intact so that the forest floor would be shaded, suppressing the growth of weedy vegetation that ignites easily and keeping the forest floor moist, which retards fire ignition. 

Unfortunately, none of the proposed vegetation management plans were acceptable to native plant advocates who want all non-native trees in project areas in Oakland to be destroyed and the land replanted with native plants and trees.  The plan they are demanding is a native plant restoration, not a wildfire hazard mitigation plan.  Since they have successfully prevented Oakland from addressing wildfire hazards for eight years, we might assume they aren’t concerned about wildfire. 

A fourth version of the plan and a new Environmental Impact Report are expected to be published in September 2023 and there will be a new public comment period in October.  Based on written and oral public comments at public hearings, we predict that the revised plan is likely to be far more destructive than previous drafts of the plan.  Based on that prediction, I am alerting you to the need to read the revision and write a public comment.  Please ask to be notified of the publication of the plan by sending an email to info@oaklandvegmanagement.org .

Update:  The revised Oakland Vegetation Management Plan and revised Draft Environmental Impact Report were published on September 20, 2023.  These documents are available HERE.  There will be a public hearing by the Oakland Planning Commission on November 1, 2023.  The deadline for public comment will be November 4, 2023.  Comments can be submitted by email DEIR-comments@oaklandvegmanagement.org or by mail to Montrose Environmental, attention Ken Schwarz, 1 Kaiser Plaza, Suite 340, Oakland CA 94612.

When I have read the revised plan and its revised EIR, I will post a draft of my public comment on the draft by October 1st. 

– Webmaster, Conservation Sense and Nonsense, September 20, 2023

What do opponents of previous plans want?

There is a wide range of opinions about a vegetation management plan for Oakland.  I will use the public comment of the California Society of American Foresters (SAF) on the third version of the VMP as a representative opinion and the best available predictor of where the fourth revision is likely headed.  The entire comment of the Society of American Foresters (SAF) is available HERE and here are some of the revisions SAF is asking for: 

  • “Ecological restoration should be a goal of the VMP, including the establishment of native plant species where nonnative species dominate…Thinning of dense stands of nonnative tree species should only be done as part of an overall strategy of restoration, i.e., the goal of any tree removals should always be to eventually convert these stands to native tree or vegetation cover in order to build greater ecological resiliency.”
  • “In concert with the goal of ecological restoration, adaptive management in light of climate change should guide management practices and restoration plans. Adaptive management strategies that incorporate new information and changing conditions will be critical to ecosystem restoration. Annual grasslands may become more dominant, oak woodlands less so in the planning area in the future as climate changes. Management targets in many cases will have to be based on anticipated future conditions.”
  • “However, if thinning is kept as the desired practice, we ask that you design each entry to be sufficiently intensive to assure that tree crowns will not close before the next thinning entry (10 years from now?) and indeed is sufficiently thinned to allow work towards establishing native vegetation in these stands.”
  • “The use of prescribed fire as a vegetation maintenance tool should have been considered and included in the VMP especially on ridges where fire moving from adjacent jurisdictions might occur, or along power-line transmission corridors.”
  • “The vegetation management zones along roadsides, especially along routes of egress, should be modified to extend 100 feet from roadside edges and should include any trees with underlying structural or health conditions that are tall enough to fall onto streets and roads. This may in some cases require looking outside of the 100-foot roadside clearance.”
  • “It is important that the use of triclopyr herbicides is included to treat cut stumps in eucalyptus to prevent sprouting. Glyphosate herbicides will not be effective in treating eucalyptus stumps and will result in resprouts.”
  • “There should be an Ecological Restoration Guide added to the appendices…This new appendix would outline the City of Oakland’s current ecological restoration efforts, identify stakeholders (e.g., city departments, Oakland Wildlands Stewards, etc.) and their roles…”

Native plant restoration, NOT wildfire hazard mitigation

The Society of American Foresters (SAF) is asking the City of Oakland to make a commitment to eradicating all non-native trees in project areas and replacing them with native plants.  Such a plan would not reduce wildfire hazards in Oakland because native vegetation is not inherently less flammable than non-native vegetation.  Most wildfires in California occur in native chaparral and native conifer forests.

The plan proposed by the Society of American Foresters (SAF) is a native plant restoration plan, NOT a wildfire hazard mitigation plan.  Their proposal would destroy much of Oakland’s urban forest, which would not be replaced by native trees:

  • Non-native trees were planted in Oakland in the 19th century because there were few native trees: “Vegetation before urbanization in Oakland was dominated by grass, shrub, and marshlands that occupied approximately 98% of the area.” (1)  Non-native tree species in the East Bay are adapted to soil and microclimate conditions that are not suitable for native species.
  • Grassland was the dominant vegetation type of pre-settlement Oakland partly because of the land management practices of Native Americans and the stock grazing of early settlers:  “Native Americans played a major role in creation of grasslands through repeated burning and these disturbance-dependent grasslands were maintained by early European settlers through overstocking of these range lands with cattle and sheep. Twentieth century reduction in grazing, coupled with a lack of natural fires and effective suppression of anthropogenic fires, have acted in concert to favor shrubland expansion.” (2)
  • Grassland in California is not native to California.  Mediterranean annual grasses were brought to California in the early 19th century by the grazing herds of Spanish-Mexicans.  California’s native bunch grasses are not adapted to heavy grazing by herds of domesticated animals.  The grassland of California is about 99% non-native (Allan Schoenherr, A Natural History of California, UC Press, 1992).  Attempts to convert annual grasslands to native bunch grass have not been successful.  A team of scientists at UC Davis spent $450,000 and 8 years trying to convert 2 acres of grassland to native bunch grasses without success.  Grassland that will replace our urban forest will not be native. 
  • Grass is easily ignited and fires move quickly through grassland, particularly in a wind-driven fire.  The deadly, destructive fires in Maui, Hawaii are a case in point.  When agricultural fields of sugar cane, pineapple and other tropical fruit left Maui they were quickly succeeded by non-native grass that was considered a factor in the spread of fire. (3)  Dormant, dry annual grassland in the East Bay Hills will be more flammable than the living vegetation that native plant advocates want to destroy.
  • A small redwood grove was the only pre-settlement exception to the otherwise treeless Oakland hills:  “…for thousands of years [the Oakland hills] were treeless meadows, visited seasonally under Indigenous management…The one exception was the redwood groves of the southern Oakland Hills, a restricted forest that extended a few miles eastward from upper Dimond Canyon over the ridgetop to the outskirts of Moraga.” (4) Much of this grove still exists today because coastal redwoods are vigorous resprouters when they are burned or cut down.
  • SAF also predicts a vegetation type-conversion from forest to grassland:   “Annual grasslands may become more dominant, oak woodlands less so in the planning area in the future as climate changes.” Grassland will naturally succeed to shrubland without regular burning, which SAF recommends to reduce fuel loads.
  • Prescribed burns in densely populated urban areas are rarely approved by Bay Area Air Quality Management District because they pollute the air and often cause uncontrolled wildfires. California law regarding liability for damage caused by prescribed burns was revised in 2022 to provide legal protections for those who manage prescribed burns.  The revised law lowers the standard for liability to gross negligence from a previous standard of simple negligence. (5)

Consequences of landscape conversion to grass and shrubs

Destroying thousands of trees will increase air pollution and reduce air quality.  Destroying thousands of trees will increase greenhouse gas emissions causing climate change by releasing the carbon stored by the trees that are destroyed and reducing carbon sequestration going forward because the destroyed forest will not be replaced by a forest of native trees.

There was little biodiversity in Oakland’s pre-settlement forest:  “Oakland’s original species composition has increased from approximately 10 tree species to more than 350…Today [1993], only 31% of existing trees are native to Oakland, the plurality of trees (38%) are native to Australia/New Zealand.”  (1)  Destroying thousands of non-native trees in Oakland will reduce the biodiversity of our forest.  A more diverse forest is more resilient, particularly in a changing climate, with extreme and variable weather conditions.

Increasing 300 miles of roadside clearance from 30 feet (as proposed by the 3rd version of the VMP) to 100 feet (as proposed for the 4th version of the VMP) will produce wood debris on a scale that cannot be disposed of.  We know what the outcome will be because of a similar project on Claremont Ave, where eucalyptus was clear cut 100 feet from the north side of 1.1 miles of the road in fall 2020.  Below are pictures of the piles of wood chips and logs that remained along that stretch of road for about 9 months while project managers tried to figure out what to do with the wood debris, which was eventually dispersed throughout the hills.  UC Berkeley implemented the project with funding from Cal-Fire. 

The north side of Claremont Ave. was clear cut 100 feet from the road. The south side of the road was not cut because the trees are native.   There is a creek flowing at the bottom of the canyon that creates the moist conditions needed for native trees, which will not grow where non-native trees now grow. Photo by Doug Prose, courtesy Hills Conservation Network.
One of many piles of logs, Claremont Ave, November 2020. It took about 9 months for the logs to be dispersed along roads in the hills. Photo by Doug Prose, courtesy Hills Conservation Network.
One of many piles of wood chips, Claremont Ave, November 2020

The roads in the East Bay hills are now lined with logs, preventing people from pulling off the road. No native plants or trees were planted after the trees were destroyed. Three years later, the clear cut roadside is vegetated with non-native annual grasses and coyote brush, a pioneer native shrub.

The project on the property of UC Berkeley was very small in comparison to the Oakland vegetation management plan that will clear cut 300 miles of roads, producing at least 300 times the amount of wood debris.  What will Oakland do with the wood debris that is produced from the destructive VMP that native plant advocates demand?  Tons of wood debris lying on the ground is far more flammable than living trees, which is another indication that the VMP that native plant advocates demand is not about mitigating fire hazards. It’s about their preference for a native landscape that is not less flammable than the landscape they demand be destroyed.  Like all Mediterranean climates, our native vegetation is fire adapted and fire dependent.  A significant number of our native species will not regenerate in the absence of fire.  Most wildfires in California in the past 5-10 years have occurred in native chaparral and native conifer forests. 

NY Times reported that 150 homes burned in this wind-driven fire in San Diego in 2003, but the eucalyptus surrounding the neighborhood did not burn. The flammability of eucalyptus trees is exaggerated to justify their destruction. NY Times photo

The more trees that are destroyed, the more herbicide will be required to prevent the trees from resprouting.  SAF is correct in saying that tricopyr will be needed to kill the roots of the trees to prevent them from repsouting.  Glyphosate will not accomplish that task.  Triclopyr is more toxic than glyphosate. Triclopyr has a signal word of “warning” and glyphosate has a less toxic signal word of “caution.”  Triclopyr kills the roots of woody plants by traveling from the cut stump to the roots of the plant in the soil.  Triclopyr is known to kill mycorrhizal fungi in the soil, which are essential to the health of plants growing in the soil.  The more herbicide that is used to kill the roots of destroyed trees, the less likely a newly planted native landscape is to survive.  All the more reason to assume that the destroyed forest will not be replaced by a native landscape.

In Summary

  • The landscape that native plant advocates demand for Oakland will be predominantly non-native annual grasses.
  • Native trees will not replace the trees that are destroyed because they are not adapted to most places where non-native trees now live and because there is no available funding to purchase native plants, plant them on thousands of acres of public land, and irrigate them until they are established.  Similar fuels management projects done by East Bay Regional Parks District, East Bay Municipal Utilities District, and UC Berkeley have not planted a native landscape to replace trees that have been destroyed.
  • Non-native annual grasses will naturally succeed to shrubs in the absence of frequent fire.  Shrublands are more flammable than the existing urban forest because fire travels on the ground, unless wind-driven fire ignites tree canopies.  In that case everything burns, both native and non-native trees.  The wind-driven fire in Oakland in 1991 spared no trees in burned areas, whether native or non-native.  
  • The project would produce many tons of flammable wood debris that has no commercial value and no place to be safely disposed of.
  • The loss of our urban forest will increase air pollution in Oakland, contribute to greenhouse gas emissions causing climate change, and raise temperatures in a city that is already a heat-island. 
  • Herbicides needed to prevent the urban forest from resprouting will poison the soil and suppress the growth of a new landscape.

If you live in Oakland City Council District 4 or 6, you are likely to be directly affected by Oakland’s vegetation management plan.  The most effective way to influence the VMP is to express your opinion to your representative on the City Council, as well as our at-large representative on the Council.  Contact information for members of the Oakland City Council is available HERE.

(1) David Nowak, “Historical vegetation change in Oakland and its implications for urban forest management,” Journal of Arboriculture, September 1993
(2) Jon E. Keeley, “Fire history of San Francisco East Bay Region and implications for landscape patterns,” International Journal of Wildland Fire, September 2005.
(3) https://www.nytimes.com/2023/08/13/us/hawaii-wildfire-factors.html
(4) Andrew Alden, Deep Oakland: How geology shaped a city, Heyday, 2023.
(5) https://kion546.com/news/2022/01/04/new-california-law-changes-liability-for-out-of-control-prescribed-burns/