extinction – 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 18^th 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.

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.”

Thomas Halliday, Otherlands, A Journey Through Earth’s Extinct Worlds, Random House, 2023
https://www.nytimes.com/2024/01/04/science/flower-sex-evolution-bees.html?searchResultPosition=1
https://en.wikipedia.org/wiki/List_of_C4_plants
Erik Lundgren et.al., “Functional traits—not nativeness-shape the effects of large mammalian herbivores on plant communities,” Science, February 2, 2024
David Yih, “Land Bridge Travels of the Tertiary: The Eastern Asian-Eastern North American Floristic Disjunction, Arnoldia, 2012

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.

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:

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.

Starlings, vagrants, and dead birds

I was introduced to the nativist mindset about birds over 30 years ago by an ominous encounter with a birder in Florida. The sound of gunfire drew our attention to a man with a shot gun on the lawn of our motel. Starlings were falling around him, where he quickly finished them off with a vigorous stomp of his booted foot. We were unfamiliar with the hatred of non-native species at that time and asked him why he was killing the birds. He seemed stunned to be questioned. He explained, as though speaking to retarded children, that the starlings were “trash birds” that must be killed. Following a basic rule of survival, we walked away from a person wielding a gun.

Starling in breeding plumage. Creative Commons – Share Alike

I was reminded of that incident by a recent article in the magazine of the Cornell Ornithology Laboratory. The author of the article studied starlings for her Ph.D. dissertation. She was well aware of their reputation as competitors of native birds and consumers of agricultural crops, but belatedly she was having second thoughts about their reputation as invaders: “Our national conversations about racial equity and political dissent in the last year reminded me that I must change my behavior in response to crises. It has also encouraged me to consider my impact on others, human and starling alike.” She wondered if calling starlings “aliens” might contribute to the negative opinion of human immigrants: “But I can’t help thinking of the parallels with countless stories about human “aliens.” Whether we intend this comparison or not, labeling immigrants “invaders” and “aliens” isolates those who cross a border in search of a safer, stabler life.”

Comments on the article dispel doubts that such a connection between humans and birds perceived as “alien” exists in the minds of at least some nativists. This is the concluding response to my attempt to discuss the issue with a nativist: “I am glad I will not live to see your crap filled America of endless third world suburbs, starlings, and house sparrows. I wish I could live long enough to see it gasp its last breath.” Strangely, this person seems to be angry about something that he fears will happen in the future, but isn’t visible to him now.

The recent fatal shooting of 10 African-American citizens by an 18-year-old self-avowed white supremacist was also an opportunity to witness the fear, hatred, and violence generated by the use of the word “invasion” to describe immigration, as reported by National Public Radio’s News Hour shortly after the shooting: “The alleged Buffalo gunman isn’t the first mass shooter to talk about an “invasion” of non-whites. Last week’s mass shooting in Buffalo has turned attention once again to something known as the replacement theory. It’s a baseless and racist conspiracy theory that powerful elites are trying to replace white Americans with nonwhites and that these elites are allowing a so-called invasion of nonwhite immigrants. That word, invasion, has been used a lot lately by some Republicans and immigration hard-liners”

This racist conspiracy theory bears a remarkable resemblance to the theory of invasion biology, which claims that the mere existence of non-native plants and animals is a threat to native species. Although there is little empirical evidence of that threat, the myth persists and is used to justify the destructive attempts to eradicate harmless plants and animals.

The consequences of fear, anger, and dread

The misnamed USDA Wildlife Services killed over 1.7 million animals in 2021, including 1,028,648 starlings and “dispersed” 10,631,600 starlings. Only 400,000 of the animals they killed were native; 1.3 million were considered “invasive.” The mission of USDA Wildlife Services is “to provide Federal leadership and expertise to resolve wildlife conflicts to allow people and wildlife to coexist.” Since 1886, Wildlife Services has killed millions of animals every year that are considered pests by humans.

Is all that killing effective? Does it actually reduce populations of the species perceived as a threat? What does it accomplish?

Farmers have been at war with birds for as long as humans have engaged in agriculture, some 10,000 years. Crows, grackles, blackbirds, and starlings are often targets of efforts to eliminate them in agricultural areas. Between 1939 and 1945 about 3.8 million crows in Oklahoma were killed by dynamiting their roosts. A study of that effort found no evidence that either the population of crows or crop production was affected by that campaign because nature adjusts: “Destroy a chunk of a population, now there’s more food for the ones who remain. Through a variety of physiological responses—shorter gestation periods, larger broods, delayed implantation—a well-fed individual produces more offspring than one that’s struggling or just getting by.” (1) This balancing act is known to be true of many other animal species, such as coyotes and rodents.

The Four Pests campaign was one of the first actions taken in the Great Leap Forward in China from 1958 to 1962. The four pests to be eliminated were rats, flies, mosquitoes, and sparrows. The campaign depleted the sparrow population nearly to extinction. The sparrows had eaten insects that killed the crops. In the absence of sparrows a plague of locusts contributed to the Great Chinese Famine, killing tens of millions of Chinese between 1958 and 1962. Ironically, the Chinese ended up importing 250,000 sparrows from the Soviet Union to replenish the population.

As is often the case with attempts to kill animals, the decision is usually made without understanding the role the animal is playing in the ecosystem. There are usually positive as well as negative impacts of every member of the food web. When we focus only on the negative impact, there are often unintended negative consequences of eliminating a member of an ecological community.

Starlings are considered an agricultural pest in the US, but they are not routinely killed in England or Europe where they are native, although they probably eat just as much agricultural crops there. The New York Times recently published an article about starling murmurations in Europe. The videos and photographs of these huge flocks of starlings moving in coordinated patterns are beautiful and remarkable. They draw crowds of people who are transfixed by the spectacle.

A study of the impact of starlings in Europe explains why starlings are usually not killed in Europe: “Starlings that cause damage on migration or in winter may have bred in countries, some of them outside the EEC, where the birds cause no damage and are held in esteem on account of their valued role as insect predators, their educational and their aesthetic values. Claims from countries where Starlings winter that breeding populations should, by some means, be limited are unlikely to be received sympathetically by those to the northeast who eagerly await the Starlings’ return in spring… On grounds of effectiveness, feasibility, cost, humaneness and environmental safety a population limitation strategy is unlikely to be an appropriate solution…The potential for Starlings to reestablish large flocks at good feeding sites after heavy mortality has been inflicted locally indicates that even local population reduction is only temporarily effective in reducing damage.”

The popular urban legend about starlings is that they were brought to the US in the 19^th century by a dedicated fan of Shakespeare who wanted to introduce all the birds mentioned by Shakespeare to America. Over one hundred years later, scientists have used molecular analysis to disprove that myth. In fact, starlings were brought to America earlier by more than one person to more than one location, including to New York by a Shakespeare fan. This is a reminder that there is always more to know and that we must remain open minded to learn new information as science moves inexorably forward.

Words matter: Vagrants or Scouts?

Birders get excited about seeing birds where they don’t usually see them. When they do, they usually call them “vagrants,” a word that is a synonym for tramps, drifters, beggars, hobos, even homeless people. It’s not a surprising word choice in a crowd that is heavily biased in favor of natives.

An article in New York Times suggests that the word “vagrant” is no longer an accurate description of the birds being seen where they haven’t been seen in the past. The explanation for their surprise visit is often an indication that they are adapting to changes in the environment, including climate change and associated changes in vegetation and insect populations. They are in unfamiliar territory in search of what they need to survive. Perhaps their usual nesting site is now a parking lot. Or perhaps the vegetation they need did not survive a severe drought. Or pesticides have killed the insects they need to feed their chicks during nesting season. They are scouts, not vagrants. They aren’t lost. They are seeking a safe haven.

As the climate changes and human activities continue to encroach on the natural world, plants and animals must move, adapt, or die. The least we can do is stay out of their way. The fact that birds are the most mobile animal class is something to celebrate, not lament. Their mobility makes them more likely to survive changes in the environment. A recent study reported that 13% of bird species are threatened with extinction, compared to 25% of mammal species, 21% of reptiles and 40% of amphibians.

Mary Roach, Fuzz, W.W. Norton & Company, 2021

The Dawn and Dusk of the Age of Mammals

In Beasts Before Us, paleontologist, Elsa Panciroli, traces the evolutionary history of the mammal class of the animal kingdom, of which humans are members, to its origins about 300 million years ago. It’s a tedious recitation of multitudes of now extinct species from their earliest ancestors up to the dawn of the age of mammals that began 66 million years ago after the abrupt end of the age of dinosaurs. But it’s also a rewarding read because it reminds us of our close relationships with other animals as well as the ways in which we are different. Those differences predict which mammals will survive the forthcoming sixth great extinction that humans have inflicted on life on Earth.

Mammals living today have in common only one characteristic that distinguishes them from other classes of close relatives. The subdivisions of mammals alive today have mammary glands that produce milk to feed their young. The three subdivisions of mammals are monotremes, marsupials, and placentals. Monotreme species alive today are platypus and echidna whose young are hatched from eggs, but are milk fed by their mothers. Marsupials are born at an undeveloped stage and carried to term in their mothers’ pouch. By far the largest group, placentals carry their developing offspring inside the mothers’ abdomen until birth.

The earliest ancestors of mammals were four-legged vertebrates called amniotes. Amniotes were named for the membrane that lined the hard shells of their eggs, protecting the embryo. The development of the amniotic membrane provided protection needed to lay and hatch eggs on land rather than the ocean where earlier forms of life lived. This evolutionary development was associated with the transition of life from the ocean to the land. The earliest amniotes diverged to take two different evolutionary paths, one as reptiles and dinosaurs (sauropsids) and the other as mammals (synapsids). Pause here briefly to contemplate our close relationships with other animals.

The Science of Paleontology

Beasts Before Us is also interesting as a history of paleontology, the branch of science that studies fossils of plants and animals to determine the evolutionary history of life. Beasts focuses on advances in modern paleontology, but this article takes readers further back in time to appreciate how recently we learned about the scale of past extinctions that predict future extinctions.

Prior to the 19^th century, an understanding of extinction was inconsistent with prevailing Western belief that the world was created by God as complete, perfect, and unchangeable. In the late 17^th century fossils of extinct animals were discovered that appeared to be unlike any living species. Inquiring minds began the search for an explanation for what happened to these unknown species.

George Cuvier is credited with establishing the modern concept of extinction in a lecture to the French Institute in 1796. Cuvier is sometimes called the “founding father of paleontology.” He rejected the theories of evolution, believing instead that extinctions could be explained by “cyclical creations” and catastrophic natural events such as floods.

The fossil record is limited in what it can tell us about life in deep time because it does not preserve the remains of extinct species with equal reliability. Bones survive to tell the tale with greater accuracy than soft tissues and plants. Paleontology is developing techniques to compensate for gaps in the fossil record, drawing from other scientific disciplines, such as botany, biochemistry, mathematics, and engineering.

Since more than 99% of all species that ever lived on Earth—more than five billion species–are now extinct, we can only imagine the difficulty of the task of piecing together the complete phylogenetic tree of life. Beasts Before Us gives us a current view of what has been accomplished to date. Clearly it is not the end of the story and much of the story is still speculative.

Divergent Evolution

The 300-million year journey from the first ancestors of mammals to modern mammals of today is a story of divergent evolution, the accumulation of differences between closely related populations within species that lead to new species. Tracing that long process was until recently dependent upon the fossil record and was therefore focused on changes in bone structure, particularly teeth, jaws, and skulls for which the fossil record is more intact.

Evolutionary tree of mammals. Wikimedia Commons

These bone structures are important clues about the diet of animals. The teeth of herbivores, insectivores, and carnivores are different. “Mammal fossils can be distinguished and named based on their teeth alone.” (1) Nearly half of all mammal species are rodents, a name that comes from the Latin word for gnaw. Their long front teeth grow continuously as they are ground down by gnawing on tough plant material such as tree bark in the case of beavers or the wooden shingles on my home in the case of squirrels.

The digestive systems of mammals also diverged to accommodate their different diets (or vice versa). Carnivores typically have a short intestinal track where digestion is accomplished with enzymes and resident microbial communities. Herbivores have a longer digestive system in which plant material is fermented in a series of separate chambers in the case of ruminants (cows, sheep, deer, etc.).

Divergent evolution creates diverse species with diverse abilities to exploit different ecological niches while reducing competition between species. Shortly after the divergence of mammal and reptile lineages, the characteristic most consequential to the fate of those lineages was endothermy (warm-bloodedness) in mammals and ectothermy (cold-bloodedness) in reptiles. The divergence of this characteristic occurred about 250 million years ago, shortly after the divergence of mammal and reptile lineages.

Only mammals and birds are generally capable of generating their body heat internally. Over millions of years they also evolved insulation that conserves body heat with fur, feathers, and blubber in the case of marine mammals. A diet high in sugar and fat also helps to maintain body heat. Cold blooded animals depend on external heat sources such as sunlight to be active. These crucial differences in mammals and reptiles relegate them to different ecological niches to which they are suited, for example:

Mammals and birds can survive in colder climates than reptiles.
Mammals and birds can be more active at night when it is cooler.
Mammals and birds can be more active for longer periods of time than reptiles.
Mammals and birds can live below ground where it is colder in summer and warmer in winter than above-ground temperatures.
On the other hand, mammals and birds must eat more and more frequently than reptiles.

These significant differences are partly responsible for the sudden transition from the age of dinosaurs to the age of mammals 66 million years ago. During the age of dinosaurs, mammals were small, lived below ground, and ate primarily insects. This lifestyle avoided competition with huge dinosaurs that dominated the land.

Scale diagram comparing a human and the largest-known dinosaurs of five major clades Creative Commons Attribution-Share Alike 4.0 International license.

When the asteroid hit the Earth 66 million years ago, the climate was suddenly and drastically transformed from a tropical climate to a cool, partly sunless climate. Vegetation adapted to a tropical climate quickly died, depriving dinosaurs of their food if they weren’t killed outright by the impact.

Beasts paints a vivid and dire picture of the cataclysmic event that ended the age of dinosaurs. The asteroid created a crater almost 100 miles in diameter and 12 miles deep. “An earthquake larger than any recorded in human history would have made the Earth reverberate like a bell. The thermal shockwave would have flash-fried all life for hundreds of miles. The blast of air probably flattened forests as much as 1,000 kilometers away…[the impact] created a mega-tsunami at least 330 feet in height…[that] mounted the coasts of North American and barreled inland like a liquid steam-roller…The dust in the atmosphere swirled its way around the planet until it enclosed all life in its smothering grip. The sun rose, but as little as half of its light could penetrate the dust in the atmosphere. The sulphur in the dust combined with water droplets to rain sulphuric acid on the land, burning away the green vegetation…Few animals bigger than a Labrador dog survived the extinction event.” (1; not verbatim)

The fifth extinction predicts the consequences of the sixth extinction

Small mammals were safely below ground and they didn’t require the great quantities of plant food required by dinosaurs. Mammals inherited the Earth and over millions of years they evolved into some 5,500 mammal species today of which 90% are still small bodied, most of them rodents.

The final chapter of Beasts uses the consequences of the fifth extinction that ended the age of dinosaurs to predict the consequences of the anticipated sixth extinction because “Humans are replicating many of the conditions of previous mass extinctions.” (1)

Animals are likely to become more active at night, when temperatures are cooler.
Animals are likely to find some respite by living below ground where temperatures are more moderate in winter and summer.
Animals will move to more temperate regions if they can.

The animals that are most likely to survive will be small generalists, who need less food, are not fussy about what they eat, and are more capable of tolerating heat. Think rats. Beasts advises, “If I were you, I’d say goodbye to any wild animal bigger than a pig—zoos are likely to be the only refuges for them in the future we are creating.”

Birds were the only descendants of dinosaurs to survive the fifth great extinction. They are expected to fare better in the sixth extinction for much the same reason: they can be active at night; they eat insects as well as plants; they are more mobile than most classes of animals. We often hear dire predictions of the fate of birds, but in fact they are less threatened than other classes of animals. A recent study reported that 21% of reptiles are threatened with extinction, a higher risk than birds (of which about 13 percent of species are threatened with extinction) and slightly less than mammals (25 percent). Amphibian species are at highest risk with about 40 percent of species in danger of extinction. We hear more about birds because their popularity motivates greater media coverage about them.

I will also presume to give my readers some advice.

Quibbling about whether native plants are superior to non-native plants is like arguing about the color of the lifeboat. It really doesn’t matter. Soon enough we will be glad to have ANY vegetation that is capable of living in the climate we have created. The universe is indifferent to the survival of any specific species of life.
You can do more for the environment and the animals that live in it by stopping the use of pesticides than by planting native plants.
Be humble about what you think you know. Many important scientific concepts such as evolution and extinction are less than 200 years old and the cause of the extinction of dinosaurs was discovered less than 50 years ago. What you learned 50 years ago may need to be reconsidered and revised. A rapidly changing situation requires that we keep an open mind to new information.
Set meaningful priorities. Climate change is an existential threat to all life on Earth. Ask yourself how we can justify the destruction of healthy trees that sequester the carbon that contributes to climate change?

Elsa Panciroli, Beasts Before Us: The Untold Story of Mammal Origins and Evolution, Bloomsbury Sigma, 2021

Fact vs. Fiction: The real threats to native plants in California

The enduring fiction of the native plant movement is that the existence of non-native plants threatens the existence of native plants by “crowding out” native plants. If that were true, we should expect to see some evidence of such a causal relationship after 250 years of steadily increasing numbers of non-native plant species. But we don’t.

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.” (1)

Although climate change is not cited as the cause of any of the known plant extinctions in California, Rejmanek predicts that climate change is likely to be a factor in the future, not only because of the impact of drought and higher temperatures, but also because non-native plants may be better adapted to changed conditions.

There are over 1,000 naturalized non-native plant species in California. Their presence is associated with human disturbance. Naturalized non-native plants are a symptom of disturbance, not the cause. The impact of non-native plants on native plants cannot be separated from other factors that created the conditions for success of non-native plants.

Specialized insects are exaggerated

Another popular fiction among native plant advocates who love to hate non-native plants is that specialized insects—especially pollinators—require specific native plant species. Again, the record of plant extinctions in California does not support that myth: “…there is no indication that the loss of pollinators was an important factor in plant species extinctions in California. [For example, one of the native plant species extirpated in California] has many documented non‐specialized pollinators. There does not seem to be any particular dispersal mode associated with presumably extinct plants in California.” (1)

Putting plant extinctions into context

Mediterranean Climates are found in coastal temperate zones. Mediterranean climates are characterized by hot dry summers and mild wet winters.

Setting sub-species aside, there are 5,280 identified native plant species in California and 28 known extinctions of native plant species, including 15 plant species known to still exist in other states. Only .53% of California native plants are known to be extinct in California, about one-half of one-percent. Does that seem like a lot? Rejmanek compared the extinction rate in California with other Mediterranean climates. The extinction rate of native plants in California is similar to those in the European Mediterranean Basin, South Africa, and Australia, but a little greater than the rate in Chile, where there are fewer endemic plants that exist only in Chile. Endemism is associated with small native ranges and small populations that are more vulnerable to extinction.

Why are there many endemic plants in California?

About 40% of native plant species in the California Floristic Province are endemic, found only in California and in most cases only in small areas within California, including our off-shore islands. Their small populations in isolated geographic areas, sometimes within unique ecosystems, such as alkaline sinks, make them particularly vulnerable to extinction.

The evolutionary history of endemic plant species explains why there are so many in California. Endemic plants are close relatives to plants that exist elsewhere and are sometimes plentiful where they came from. For example manzanita is a genus of chaparral shrub that is plentiful in California, but there are also many rare endemic manzanita species that occur only in small areas and small populations. There are several endangered manzanita species in the Bay Area (pallid, Raven’s, Franciscan).

Franciscan manzanita is one of 2 endangered manzanita species in San Francisco. There is one individual plant left of each of these two manzanita species. There are many endemic plants and insects in San Francisco and several are now extinct. San Francisco has a complex, diverse geology and topography and it is surrounded on 3 sides by water, creating many small, isolated microclimates in which many endemics have evolved.

The geography of California explains why the evolution of a plant species diverged from its plentiful ancestors to become an endemic species in a small geographic area. Plants move around in a wide variety of ways, most natural, without the aid of humans. Their seeds are dispersed by animals and birds that eat them or inadvertently carry them to another location. Sometimes their seeds are carried on the wind or brought to islands by storms and currents.

When a plant arrives in a new location that is isolated from its original home and therefore cannot mate with its relatives, it begins its own, independent evolutionary history. Each successive generation is reacting to its new environment, rewarding its fitness with its new home with a successful new generation. Each generation rolls the genetic dice, its genome drifting away from its ancestors in a random way. Occasionally a mutation will occur that alters the evolutionary trajectory. Eventually, the plant in its new home is sufficiently genetically distinct that taxonomists are ready to call it a separate species. Naming a new species is a judgment call, often questioned by some taxonomists, called “lumpers” as opposed to the “splitters” who are ready to name it a new species.

The factors that result in endemic species are many, but broadly speaking they are mobility and, ironically, isolation. California is one of the most geographically diverse states in the country, with corridors for mobility, but many barriers that create isolation. Gordon Leppig describes California’s geographic diversity in Beauty and the Beast: California Wildflowers and Climate Change, published by California Native Plant Society: “The state’s natural wonders include five deserts, the highest and lowest points in the continental United States, the third-longest state coastline (about one thousand miles), the most national parks (nine), the most federally designated wilderness areas (more than 140), the highest percentage of wilderness in the contiguous United States (14%), the most diverse conifer assemblage outside the Himalayas, the most federally listed species….” The multitude of different ecosystems with unique microclimates produces one of the most diverse floras in the world.

Click on the picture to watch the movement of tectonic plates over one billion years. Watch California slowly emerge as the jigsaw puzzle takes shape. California is the edge of two tectonic plates that collide and grind past one another perpetually, uplifting and dropping the land into fractured geomorphic pieces.

Human activities penetrate the barriers that created genetic isolation in the past. Our roads become corridors for the biological exchange that threatens small, isolated pockets of rare plants. Trade and travel has ended the isolation of off-shore islands. Our roads and dams also create new barriers for mobility. In other words, we are altering pre-settlement corridors and creating new ones. We should expect consequences for our ecosystems for the changes we have made.

Given the number of rare and endemic plants in California and the changes in the environment required to accommodate nearly 40 million human Californians, it seems that extinction of less than one-half of one percent of native plants is a surprisingly small loss.

(1) Marcel Rejmanek, “Vascular plant extinctions in California: A critical assessment,” Diversity and Distributions, Journal of Conservation Biogeography, 2017

Anthropocene: The Sixth Extinction

There have been five major episodes of massive extinctions in the 4.5 billion years that our planet has existed. All occurred within the past 500 million years because there was little known as “life” prior to that time. We are now experiencing the sixth massive extinction episode which began approximately 50,000 years ago with the dispersal of humans around the world. The causes of prehistoric extinctions are not fully known, unlike the current episode. We know that we are the cause of the sixth extinction, but we seem to be incapable of preventing it.

Prehistoric extinctions

The fifth and most recent massive extinction event occurred about 65 million years ago. It brought the age of dinosaurs to an abrupt end. There were no humans or even our primate ancestors at that time. The cause of that extinction was only recently discovered in the 1980s and even more recently accepted by most scientists. There is now general agreement that the entire environment of the planet was radically and suddenly altered by the impact of a huge asteroid that landed on what is now the Yucatan peninsula in Mexico. The impact raised a huge dust cloud that engulfed the earth and precipitated the equivalent of a nuclear winter, killing most vegetation and the animals adapted to a much warmer climate. As with all massive extinctions, it took many millions of years for the environment to recover from that event and for plants and animals to slowly evolve adaptations to the new environment.

Update: There is an alternate theory about the cause of the fifth extinction. Huge volcanic eruptions in India may have been the cause, or perhaps a contributing factor. Explained HERE.

Scale of dinosaurs compared to human. Creative Commons - Share Alike — Scale of dinosaurs compared to human. Creative Commons – Share Alike

The third and biggest extinction event occurred about 250 million years ago at the end of the Permian geologic period. Paleontologists tell us that about 90% of all living plant and animal species died as a result of that extinction event. Like the fifth extinction, the End-Permian extinction was precipitated by a sudden and radical alteration in the climate. However, less is known about what caused that change in the climate. Like our current round of climate change, there was a massive release of carbon into the atmosphere with a related drop in oxygen. These changes caused temperatures to soar and the chemistry of the oceans to acidify. Although there is not yet consensus amongst scientists, current speculation in the scientific community is that the changes in atmospheric conditions were the result of huge volcanic eruptions in what is now Siberia that emitted carbon dioxide into the atmosphere. (2)

The first massive extinction occurred about 450 million years ago just 50 million years after the first land plants began to emerge on the planet. In fact, the plants may have been a factor in the climate change that caused the extinction at the end of the Ordovician geologic period. The cooling of the climate that caused the extinction was associated with a sharp drop in carbon dioxide levels which may have been partially the result of plants that convert CO₂ to oxygen. The movement of the continents is also thought to have been a factor in the cooling because the breakup of the unified continent, Pangaea, changed the circulation of ocean currents which affect the climate on land.

All of the massive prehistoric extinctions were associated with sudden changes in climate, although human perception of time should not be imposed on the word “sudden.” These events occurred over thousands of years and are only “sudden” when compared to the 4.5 billion years of the existence of our planet.

Extinctions of the Anthropocene

Genus Homo evolved into its only surviving species, Homo sapiens, about 200,000 years ago. That’s us…humans. However, we didn’t begin to extinguish plant and other animal species until our population grew and dispersed throughout the world. And when we did, the first victims of our ability to hunt cooperatively with weapons were the megafauna, now largely gone from the world.

Megafauna are the huge animals now known primarily from their fossil remains that were so large they had no predators until humans brought their intelligence to the task of hunting which was previously limited by size and speed. Megafauna reproduction wasn’t capable of keeping up with the pace of human hunting because they had long gestation periods, many years to sexual maturity, and small numbers of offspring.

Humans reached the Australian continent about 50,000 years ago. When they arrived, Australia had its own megafauna: giant kangaroos and other enormous herbivores. Within 10,000 years the megafauna were gone and the landscape changed as grazing was significantly reduced: “With no more large herbivores around to eat away at the forest, fuel built up, which led to more frequent and more intense fires. This, in turn, pushed the vegetation toward fire-tolerant species.” (1) Conversion to grassland savanna was also accelerated by the frequent fires intentionally set by humans to facilitate their hunting.

Eurasian Mammoth on left; American Mastodon on right. Creative Commons -dantheman9758

The same shift in vegetation occurred in North America when humans arrived about 13,000 years ago and American megafauna such as mastodons and giant sloths were hunted to extinction. Grassland found in North America when Europeans arrived thousands of years later in the 16^th century was therefore not adapted to heavy grazing and was largely destroyed by domesticated animals brought by early settlers. Native Americans did not have domesticated animals.

Similar scenarios played out around the world as humans arrived, most recently on the Pacific Islands where Polynesians arrived as recently as 1,500 years ago. Huge flightless birds were found on New Zealand until they were hunted by humans just 500 years ago.

The second wave of extinctions caused by humans occurred during the age of exploration, beginning in the 16^th century. Humans wiped out many species of animals all over the world to feed their explorations and early settlements. Huge turtles were brought on board ships to feed the crew on long voyages. Passenger pigeons and American bison were killed by early settlers for food, leather, and sport.

As humans developed agriculture and domesticated animal-herding, hunting wild animals decreased. In developed countries, extinctions today are largely by-products of western civilization, through mechanisms such as climate change and global exchange of diseases and pathogens…all equally deadly to other living things.

Modern Extinctions

There are no longer any physical barriers to the exchange of pathogens and pests. Invasion biology is based on the fiction that such exchanges can be prevented or even reversed. The most deadly invasions prove otherwise:

Amphibians, especially frogs, are being wiped out all over the world by a fungal disease that is traveling fast. It is now known to exist in Central, South, and North America, as well as Australia. The means of transmission is not yet known.
Bats are dropping dead by the tens of thousands primarily in New England as they succumb to a different fungal disease. Nothing is known about how this disease is transmitted. We should probably assume that it will also spread beyond its current range.
Insects, such as the emerald ash borer that is killing millions of ash trees in the United States, have been accidentally introduced as a result of global trade.

We should expect the loss of these species to reverberate throughout the food web, although little is known about the secondary effects of the loss of species. For example, when bats are no longer available to eat insects, what will those insects eat? And what will the animals that ate frogs eat when the frogs are gone? These animals may be playing roles about which we know little and therefore cannot predict the consequences of their loss.

The spread of pathogens and insects that prey on plants could be related to climate change. For example, the pine bark beetle is a native insect that has become a serious problem in the forests of North America because mild winters associated with global warming are not cold enough to cause an annual die-back of the insects. The range of the pine bark beetle has expanded and is killing millions of acres of forests in North America.

Ecosystems are being fragmented by agricultural development. Much of the Amazonian rainforest has been reduced to isolated fragments which are not large enough to support the diverse plants and animals that occupied intact ecosystems.

Climate change…the silent killer

When we look to the distant past, we can see how levels of carbon dioxide in the atmosphere have caused massive extinctions of plant and animal species. Low levels of carbon dioxide have been associated with a cooling phase and high levels of carbon dioxide have caused temperatures to rise. We are now in a period of a huge increase in carbon dioxide levels caused by the activities of humans, particularly emissions associated with the burning of fossil fuels and deforestation. There is scientific consensus that the climate has changed and will continue to change as well as about the causes of those changes. However, we still know little about the long-term consequences of climate change.

Coral reef. Creative Commons - Share Alike — Coral reef. Creative Commons – Share Alike

One consequence of increased levels of carbon dioxide is well known and that is the acidification of the oceans. The laws of chemistry tell us that when carbon dioxide dissolves in water it forms carbonic acid. Carbonic acid dissolves shells and coral. Aquatic animals such as mussels, clams, oysters, crabs, and lobsters will be incapable of building the shells that protect their bodies when levels of carbonic acid increase. Australian scientists report that coral cover of the Great Barrier Reef has decreased 50% in the past 30 years. A paper published in 2008 predicted the imminent extinction of one-third of 800 reef-building species as a result of increased water temperature and acidity of the oceans. An estimated one-half million to 9 million species “spend at least half their lives on coral reefs.” (1)

So why are we destroying trees?

As disturbing as it is to witness the death of plants and animals which are innocent by-standers to the choices made by humans, we have some sympathy and understanding for why our political system has been incapable of the fundamental changes needed to stop the process. We burn the fossil fuels that emit carbon dioxide and other greenhouse gases to keep us warm in the winter and cool in the summer, to transport us to work and play, to power our industrial processes and many other vital functions.

But, we cannot understand why we continue to destroy millions of healthy trees (that we planted) essentially because they are out of fashion. These trees are storing tons of carbon that will be released into the atmosphere when the trees are destroyed and we will lose their ability to store carbon in the future.

We loved these trees as recently as 50 years ago. Now many people have decided that they “don’t belong” because they aren’t native. Eucalyptus is only one of many targets of this fad. Norway maples are being destroyed in communities in eastern United States for the same reason. And most of the trees being destroyed in the Midwest (because people wish to “restore” the prairie artificially maintained by Native American fires) are even native to the Midwest.

In the case of eucalyptus, the trees are expected to live in California for several hundred more years. How will the climate have changed in 300 years? Will any of the plants presently considered “native” even exist? On our present climate trajectory, the answer to that question is clearly “no.”

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Most information in this post is from these two sources:

(1) Elizabeth Kolbert, The Sixth Extinction, An unnatural history, Henry Holt and Company, 2014

(2) “Where have all the species gone?” University of California Museum of Paleontology, short course, March 1, 2014

Non-native species are NOT the “second greatest threat to species in peril”

One of many doom and gloom scenarios used by native plant advocates to frighten the public into accepting their destructive “restoration” projects is the claim that “non-native species are the second greatest threat to the survival of species in peril.”(1) Although the statement originates with a scientific study published in 1998, the context in which it was originally reported has long since been lost as it has been cited more than 700 hundred times in scientific studies according to Mark Davis.(2)

The original 1998 article in BioScience by Wilcove et.al. clearly states that the claim is not based on any actual data:

“We emphasize at the outset that there are some important limitations to the data we used. The attributes of a specific threat to a species is usually based on the judgment of an expert source, such as a USFWS employee who prepares a listing notice or a state Fish and Game employee who monitors endangered species in a given region. Their evaluation of the threats facing that species may not be based on experimental evidence or even on quantitative data. Indeed, such data often do not exist.”(3)

This caveat is rarely repeated when the claim is invoked by native plant advocates to justify their crusade against non-native plants and animals. In fact, since the statement was originally made over a decade ago, it is now repeated without reference to the original source. It has acquired the status of a mantra amongst native plant advocates that requires no citation to substantiate its “truthiness.”

The Wilcove et.al. article in BioScience in which this statement was made was heavily influenced by selecting a geographic area which is not representative of the United States as a whole. Although Hawaii is a part of the United States its rates of extinction are not typical of the contiguous states of the union. Rates of extinction are substantially higher on islands because they contain many more endemic (unique) species that do not occur elsewhere. These endemic populations are small and vulnerable to the introduction of competing species. Native populations on islands are not supplemented by immigrations as they are elsewhere.

coqui — Coqui frog is being eradicated in Hawaii. USDA photo

If Hawaii is removed from the anecdotal information in the Wilcove article, the rates of extinction are comparable to those in Canada where introduced species are considered the least important of six categories of causes of extinction (habitat loss, over-exploitation, pollution, native species interactions, and natural causes such as storms) identified in a similar article in 2006(4). This list doesn’t include climate change, which is now considered a serious threat for extinction. Similar studies in the continental United States have reached similar conclusions.(5)

At the time the Wilcove et. al. article was published there was no evidence of a single extinction (or even local extirpation) of a native plant in the continental US resulting from competition from an introduced species of plant. Clearly, the authors of this study were guilty of exaggeration.(6)

Although native plant advocates have misused this publication by taking it out of context, the authors were complicit in its misuse by selecting a geographic area that is not representative of the United States. Non-native species are NOT the second greatest threat to the survival of endangered native species. In fact, they probably aren’t the third, fourth, or fifth greatest threat to native species.

We wish that native plant advocates would examine the origins of their assumptions more carefully. We believe if they did so they would modify their destructive projects to reflect a more inclusive view of nature.

(1) Wilcove, DS, Rothstein, D., Dubrow, J., Phillips, A., and Losos, E, “Quantifying threats to imperiled species in the United States,” BioScience, 48, 607-615, 1998.

(2) Davis, Mark, Invasion Biology, Oxford University Press, 2009, page 181.

(3) Ibid.

(4) Venter, O, et. al., “Threats to endangered species in Canada,” BioScience, 56, 903-910, 2006.

(5) Ibid., page 182

(6) Ibid., page 183