We have fond memories of the good old days when we could read the newspaper without questioning everything we read. That was over 15 years ago, before we became engaged in our effort to save our urban forest from being needlessly destroyed because it is predominantly non-native. Since then we have learned the uncomfortable lesson that it is necessary to be skeptical about every conventional belief about nature. Today we will examine two such beliefs related to how birds are killed in nature.
Robin and chicks. Courtesy SF Forest Alliance
Cats are presumed to be the primary predator of birds
To illustrate how pervasive the belief is that cats kill birds, we start with an internet search, “cats kill birds.” Here’s a selection of articles available on the internet that make that claim:
“Cats kill 3.7 billion birds annually”
“Outdoor cats kill between 1.4 billion and 3.7 billion birds a year”
Only one of the 88 mammals was a domestic cat. The detailed list of all 242 predators is fascinating reading, which we recommend to you.
We understand that nest predation is not the only cause of bird mortality. However, most bird death occurs in the first year of life according to the Cornell Laboratory of Ornithology, so clearly nest predation is an important factor in bird mortality. And if video cameras find virtually no evidence that cats are nest predators, then we must wonder if cats are the bird killers they are made out to be.
Like so many other assumptions of nature lovers, we wonder if people are misled by their personal experiences. In this case, most people live in urban areas and there are probably more cats in urban areas, so it seems probable that people are more likely to witness bird-death-by-cat than snakes, for example. But empirical studies suggest that we should not extrapolate from that personal experience to conclude that cats are responsible for most bird mortality. We will reserve judgment on that question, although we encourage cat owners to keep their cats indoors.
Are cowbirds another scapegoat for bird death?
We have also reported earlier that cowbirds are scapegoated for declining populations of song birds. Cowbirds are nest parasites, which means they lay their eggs in the nests of other species of birds. Their chicks are often bigger than the chicks of other species so they out-compete them in the nest, which implies that cowbirds could reduce the reproductive success of other species of birds. In fact, a study of a 30-year attempt to eradicate cowbirds did not find evidence that killing over 125,000 cowbirds increased the population of a rare songbird.
Yellow-billed Cuckoo. NPS photo
Today we tell our readers about a study of another nest parasite, the cuckoo, which could explain why killing nest parasites does not benefit other species of birds. The study of cuckoos was conducted over a 16-year period. It did not find evidence that cuckoos were reducing the population of other species of birds. The study hypothesizes that cuckoo chicks emit a foul-smelling substance that repels nest predators, thereby protecting its nest mates as well as the cuckoo from nest predators. So, the disadvantage of the cuckoo chick competing for food with its nest-mates is counteracted by the protection the cuckoo chick confers on the nest.
Lessons we have learned
In the past 15 years, we have learned to be skeptical. Here are a few lessons we have learned from questioning everything we read and hear about nature:
People seem to have a knee-jerk need to scapegoat someone or something without thinking carefully about the underlying causes of the problems we observe in nature.
When we hear a particular animal being blamed for a problem in nature, we turn to the scientific literature for verification to determine if there is any empirical evidence that supports that assessment. We frequently find no evidence to support the conventional wisdom. Sometimes we find evidence that contradicts the assumptions.
Even then, we must keep in mind that science is always moving forward. Science only hypothesizes and every hypothesis must be repeatedly tested. Hypotheses are often overturned as we learn more.
We do not think it is ethical to kill one animal based on the assumption that it will benefit another animal. Aside from the presumption of deciding which animal is worthy of living, we think these projects are often mistaken in the assumption that a particular animal will benefit. We believe that nature is far wiser than we are.
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
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 16th 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 16th 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
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
In “Nonnative plants: Ecological Traps,” Amanda Rodewald is quoted as saying that non-native honeysuckle significantly reduces the nesting success of cardinals by increasing nest predation:
“Typically in the wild, male cardinals that are in the best condition grab the best territories and nesting spots and breed earliest in the year. They also successfully rear more young than their less-fit competitors—an example of natural selection at work. But this pattern changes when honeysuckle invades a forest. Because honeysuckle leafs out sooner in spring than most plants, the fittest cardinals rush to mate and nest in the shrubs’ dense foliage. But instead of a gain in reproductive success, these birds pay a price. The early nesters in honeysuckle rear 20 percent fewer young than those that nest in native plants.”(1) (emphasis added)
She speculates that the probable reason for this reduced success is nest predation which she believes is greater earlier in nesting season because there are fewer nests.
We don’t know if Ms. Rodewald was accurately quoted in her interview or if she has changed her mind. However, Ms. Rodewald has published a study which says exactly the opposite:
“…these results provide no evidence that urban forests were acting like ecological traps for cardinals. Instead, cardinals in urban and rural forests had similar numbers of nesting attempts, young fledged over the breeding season, and apparent annual survival rates. Thus, these findings do not support the idea that urban forests in Central Ohio represent ecological traps for synanthropic understory birds” [birds that live in artificial habitats created by humans]. (2)
Urban forest sites in her study contained far more exotic vegetation than rural forest study sites: “Understory woody vegetation was over 50% more dense, with nearly 3 times greater numbers of exotic shrub stems than rural forests.” Exotic vegetation in this study was described as predominantly honeysuckle and multiflora rose. There was no statistical relationship between the number of nesting attempts and the composition of the landscape: “There were no significant differences in either the number of nesting attempts among years or between [urban and rural] landscapes.” (2)
This study offers several possible explanations for the reproductive success of cardinals in urban forests dominated by exotic shrubs:
“…urban forests in this study contained denser understory vegetation than rural forests.”
Therefore, there is “…increased cover provided by exotic shrubs in the urban forest.”
“…winter microclimates may be particularly important for resident birds…cities may be favorable thermal climates for birds because cities may act as ‘heat islands.’”
“Urban sites…probably provided more food sources for wintering birds. Urban forests had nearly 3 times more fruit and nearby birdfeeders than rural forests. Cardinals… were regularly seen feeding on fruits of exotic shrubs (e.g., honeysuckle, multiflora rose). Previous studies have indicated that supplemental food sources…can improve overwinter survival rates, body mass, and nutritional condition…Such changes in winter food and microclimate may explain increases in species richness and abundance of birds wintering in urbanizing landscapes around Columbus. Ohio.”
In her published study, Ms. Rodewald also contradicts her statement that greater nest predation in honeysuckle is the cause of reduced reproductive success of cardinals. In her published study, she says, “…high rates of nest predation frequently documented in urban landscapes do not necessarily translate to reduced productivity or survival.”
Ms. Rodewald’s statement that early nesting in honeysuckle is more likely to result in predation is also contradicted by another study. (3) Although this study was conducted in Ithaca, New York, the study site was also dominated by honeysuckle. This study found that the most fit cardinal males bred earliest in the nesting season and their nesting success for the entire nesting season was therefore greater than pairs starting later in the season: “These results confirm that an earlier breeding date is associated with producing more offspring in a season regardless of any possible effect vegetation density may have on nest initiation date.”(3)
Ms. Rodewald’s published study is consistent with a similar study: “Predation on Northern Cardinal nests: Does choice of nest site matter?” This study was also conducted in Ohio in a mixed landscape of both native and non-native shrubs. Non-native shrubs were predominantly honeysuckle and multiflora rose, as they were in Ms. Rodewald’s study. This study was trying to find a relationship between predation and the location of nests. Many hypotheses were tested relative to these variables: height of nest, concealment of nest, accessibility of nest, common vs. rare shrub location, proximity to habitat edge, distance to human activity.It found no such relationship: “Several hypotheses to explain differences between the location of the successful and failed nests were tested. None of these explained why the contents of particular nests were taken.”(4)
Multiflora rose. NPSAlthough cardinals had the choice of nesting in native or non-native shrubs in this 80 hectare bird sanctuary (Aullwood Audubon Center and Farm), 65% of the 121 nests in this study were in non-native honeysuckle or multiflora rose. The study tested for an association between plant species and probability of nest success by dividing all nests into two categories, one for the two dominant species of non-native plants and the other for all other plant species: “The probability of success was not associated with [plant] species category.” (4)
Only 25% of the 121 nests were successful. Although that sounds like a low success rate, it is consistent with other sources of information about reproductive success of cardinals: “Northern Cardinals have a very low nesting success rate with only 15–37% of their nests succeeding in fledging young.” (5)
This publication (4) had a very interesting theory about why nest location is unrelated to nesting success. The cardinal is unusual in having a very long nesting season from April to late-September. They have as many as 6 broods. When a nest fails, they start building a new nest in another location within 5-7 days. The female chooses the nest. Essentially, she is rolling the dice. She makes a nearly random choice of nest site and her long-term odds of nest success is primarily because she rolls the dice many more times than other species of birds: “We propose that a high incidence of predation by a rich guild of nest predators precludes the existence of predictably safe nests for cardinals. Instead, the cardinals appear simply to be well-adapted to renest rapidly in response to the near randomness of nest predation.”There are trade-offs for every potential nest location. For example, a low nest is more accessible to ground-dwelling predators such as snakes or rodents while a nest high in a tree is more accessible to nest parasites such as cowbirds. So, the cardinal mom takes her chances by making different choices and her eventual success is largely a question of luck.
Looking for “ecological traps”
We have been unable to find evidence that non-native plants are “ecological traps” for birds. When we find such claims, we turn to scientific literature for evidence. We find many studies begin with hypotheses which predict ecological harm done by non-native plants. But we have yet to find empirical studies that reach that conclusion.
The article we have critiqued in this post is a case-in-point. It starts with the report that the population of cardinals has exploded where honeysuckle has invaded. Despite that fact, the article concludes that the cardinal population is somehow harmed by honeysuckle. One wonders how the authors of that article reconcile this contradiction. Doesn’t the increased population speak for itself?
In any case, in the absence of evidence of harm, we do not believe that the destruction of existing landscapes can be justified, particularly since doing so requires large amounts of herbicide. Given the probability that the herbicides are harmful to animals, particularly soil microbes and insects, how can such destruction be justified?
Range map of Northern Cardinal. public domainRange map of Japanese honeysuckle. USDA
(2) Lionel Leston, Amanda Rodewald, “Are urban forests ecological traps for understory birds? An examination using northern cardinals, Biological Conservation, 131 (2006), 566-574
(3) L. LaReesa Wolfenbarger, “Red coloration of male northern cardinas correlates with mate quality and territory quality,” Behavioral Ecology, Vol. 10 No. 1 (1999), 80-90
(4) Tamatha Filliator, Randall Breitwisch, Paul Nealon, “Predation northern cardinal nests: Does choice of nest site matter?,” The Condor, 96, 761-768, 1994
One of the reasons why native plant advocates want the managers of our public lands to destroy non-native plants and replace them with native plants is that they believe native plants provide superior habitat for birds. However, empirical studies do not support this belief, as we have explained in earlier posts.Today we will examine an article recently published in an advocacy magazine, making the claim that non-native plants are “ecological traps” for birds: “Nonnative Plants: Ecological Traps Offering alluring habitat for songbirds, exotic plants may actually decrease the animals’ long-term survival and fitness” (1)
Japanese honeysuckle. Attribution William Rafti
The article begins auspiciously with the good news that populationsof some bird species have increased significantly in recent decades because of the spread of non-native plant species which are valuable sources of food: “…a 2011 paper, published in the journal Diversity and Distributions, concluding that the number of fruit-eating birds such as cardinals, robins and catbirds tripled during the past three decades in parts of central Pennsylvania due to the spread of nonnative honeysuckles.” (1) And then the article attempts to contradict this good news by turning to the usual nativist caveats.
Generalists vs. Specialists
Nativists claim that the animal kingdom is divided into generalists and specialists. The generalists are theoretically omnivores—they have a varied diet—and so depriving them of native plants will not prevent their survival. Specialists, on the other hand, are dependent upon a narrow range of plant or animal species for survival. We are expected to believe that specialists far outnumber generalists and that we doom them to extinction when one particular species of native plant or animal is unavailable to them.
Doug Tallamy is the purveyor of the generalist vs. specialist overstatement. We have critiqued his assumptions in an earlier post. In a nutshell, there are few mutually exclusive relationships in nature because they are a risky evolutionary strategy. The plant or animal that is dependent upon one other species is significantly less likely to survive in the long term than an animal with more dietary options. The perception that there are immutable relationships between insects and plants also underestimates the speed of adaptation and evolution, particularly of insects with large populations and short lifespans.
For example, a bird that eats insects usually eats all manner of insects as well as spiders. They are not dependent solely upon caterpillars as Mr. Tallamy seems to believe: “…warblers and chickadees rely on caterpillars for 90 percent of their diet during the breeding season, eating hundreds per day. ‘That’s a lot of insects,’ Tallamy says. ‘If you don’t have those insects, you don’t have the birds.’” (1)
According to Cornell Ornithology Lab–America’s most prestigious research institution for birds–warblers and chickadees have a much more varied diet than Mr. Tallamy believes. (We chose specific species with ranges and abundant populations in Delaware where Mr. Tallamy lives. However, the diet of all species of chickadees and warblers are similar.)
Black-capped Chickadee: “In winter Black-capped Chickadees eat about half seeds, berries, and other plant matter, and half animal food (insects, spiders, suet, and sometimes fat and bits of meat from frozen carcasses). In spring, summer, and fall, insects, spiders, and other animal food make up 80-90 percent of their diet. At feeders they take mostly sunflower seeds, peanuts, suet, peanut butter, and mealworms.” (2)
Orange-crowned Warbler: “insects and spiders.” (2) Most insects are not caterpillars and many are not herbivores.
Mr. Tallamy is focused on caterpillars because they are herbivores, that is, they eat plants. Just as he believes that the birds need native plants, he also believes that plant-eating insects need native plants. However, Mr. Tallamy disproved his own theory about an immutable relationship between native plants and insects when he supervised a graduate student whose thesis concluded:
“Erin [Reed] compared the amount of damage sucking and chewing insects made on the ornamental plants at six suburban properties landscaped primarily with species native to the area and six properties landscaped traditionally. After two years of measurements Erin found that only a tiny percentage of leaves were damaged on either set of properties at the end of the season….Erin’s most important result, however, was thatthere was no statistical difference in the amount of damage on either landscape type.” (3)
This empirical study, supervised by Mr. Tallamy, was unable to find evidence that there are more plant-eating insects in a native garden than in a landscaped garden of non-native cultivars. Yet, Mr. Tallamy continues to claim that insects require native plants and birds require those insects for their survival: “Tallamy’s research shows that birds also may be harmed indirectly because nonnative plants affect insects. He has found that the number and diversity of plant-eating insects, especially caterpillars, drops dramatically when exotic plants invade…[Tallamy said,] ‘My prediction is that birds that specialize on insect herbivores will take a bigger hit than those that eat other insects,’” (1)
The study by Mr. Tallamy’s student about the relationship between native plants and insects is not the only empirical evidence that his assumption is incorrect. We have published several articles about local studies that have found no such relationship:
Native plant advocates have also offered “evidence” of insect populations in the local eucalyptus forest. UCSF produced a video to promote their original plan to destroy most of the eucalypts on Mount Sutro (now on hold indefinitely). An arborist shows us eucalyptus leaves that have been chewed by insects. He claims that a drastically thinned forest will be healthier because it will have fewer insect predators. So, there are insects in the eucalyptus forest when it suits native plant advocates’ purposes and there are no insects in the eucalyptus forest when it does not. They want more insects when they are advocating on behalf of birds and they want fewer insects when they are demanding that trees be destroyed. It’s rather confusing.
Insects ARE important to birds
We agree with Mr. Tallamy that insects are very important to birds because they are a major source of food, especially during the nesting season when their high-protein content is vital to nestlings. Therefore, we believe that Mr. Tallamy should join us in making climate change our highest environmental priority. Because insects are cold-blooded, they are particularly vulnerable to the extreme weather conditions associated with climate change. They cannot adjust their body temperature as warm-blooded animals can in response to such fluctuations in temperature. A recent study predicts devastating consequences for insect populations in coming decades: “Our predictions are that some species [of insects] would disappear entirely in the next few decades, even when they have a fairly wide distribution that currently covers hundreds of kilometers.” (4)
We believe that a single-minded focus on native plants is misguided because in a rapidly changing climate the entire concept of “native” becomes meaningless. Just as insects are unlikely to survive radical changes in temperature, the ranges of native plants must change if species are to survive.
Stay tuned for Part II
In our next post, we will continue our critique of the article that theorizes that non-native plants are “ecological traps.” We will tell our readers about the published research that contradicts statements in the article about predation of cardinal nests in non-native honeysuckle. The author of one of the studies is quoted in this article, saying something completely different than her own published study. It’s an intriguing contradiction.
(3) Tallamy, Doug, “Flipping the Paradigm: Landscapes that Welcome Wildlife,” chapter in Christopher, Thomas, The New American Landscape, Timber Press, 2011
We are publishing a guest article by Sydney Ross Singer, Director, Good Shepherd Foundation. Dr. Singer has been a tireless defender of non-native species in Hawaii, where he lives. Nativism in Hawaii is even more destructive than similar projects in the San Francisco Bay Area.
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Barn Owl. Creative Commons 2.0 Generic.
Tens of thousands of innocent Owls and Egrets will be executed in Hawaii by the US Fish and Wildlife Service unless President Obama issues a pardon.
Cattle egrets and barn owls are an important part of Hawaii’s environment, consuming large amounts of rodent and insect pests as they were meant to do when first introduced by the government to these islands back in the 1950′s. They are protected by international migratory bird treaties, and are admired and prized by people wherever they are found.
Unfortunately, they are now being targeted for destruction statewide by the same invasive species eradicators who are killing our other introduced wildlife.
Egret. Creative Commons Share Alike.
Currently, whenever there is a conflict between egrets or owls and endangered species or airports, there have been permits required for their control in the local area where they are a problem. The US Fish and Wildlife Service has proposed lifting this permit requirement to allow the egrets and barn owls to be killed anywhere they are found, even if they are not causing any problems. It is killing the innocent today to prevent a potential problem in the future.
This is a reminder of ethnic cleansing and genocide. It is not what our great nation is about.
This slaughter of innocent egrets and owls is a crime against nature and against the people who live with and admire these magnificent birds. Making matters even worse, one of the methods that will be used to kill the birds is to attract them to slaughter areas by broadcasting their bird calls. Owls will be attracted from miles away to be shot. Egret colonies will be massacred for no reason other than their existence in Hawaii.
This “final solution” for the egrets and owls, not only controlling them where they are a problem but everywhere they live throughout the Hawaiian Islands, can only be stopped by President Obama issuing a stay on their execution. It is the Federal Government’s Fish and Wildlife Service that wants to allow unlimited open season on these birds. It is up to the President of our country to intervene on the behalf of these innocent, magnificent creatures.
As much as we dislike the destruction of plants and trees simply because they are not native, the extermination of animals is far more disturbing. There are presently two such proposed projects in the news to which the public has reacted angrily. We will start with the project in the San Francisco Bay Area which plans to kill ground squirrels and gophers in a public park in Berkeley. In this case, the animals are native. They will be killed because public land managers have decided they MIGHT be a problem in the future.
The squirrels and gophers of Cesar Chavez Park in Berkeley
California Ground Squirrel at the Berkeley Marina. Creative Commons – Benefactor 123
Cesar Chavez Park is the former garbage dump of the city of Berkeley, built on landfill. When the dump was closed in the 1990s, the garbage was not removed. It was capped with clay which was intended to contain whatever toxins were in the garbage. Then two feet of soil was put on top of the clay so that vegetation could be planted in the park. Small animals moved into the park, as we should expect.
The population of squirrels and gophers is now considered too big by land managers. Although there is no evidence that the burrows of the animals have penetrated the clay cap, the officials who are responsible for the water quality of the bay are apparently concerned that they MIGHT burrow through the clay cap: “…they are getting perilously close to the clay cap that covers the landfill. If the rodents penetrate that barrier, dangerous toxins like gasoline, lead, iron, herbicides and pesticides, could leach into the bay. So the city needs to reduce the animal population to lessen the risk, according to city spokesman Matthai Chakko. ‘We haven’t had any of the materials inside the landfill escape into the bay and we don’t want that to happen,” said Chakko. “We are trying to solve a problem before it happens.’” (1)
The population explosion is being blamed on park visitors feeding the squirrels. Squirrel-feeders have been interviewed by the media. They defend their right to feed the squirrels, which is a source of pleasure for them. It should not be too difficult to understand that many people prefer feeding squirrels to killing them. (However, we do not encourage people to feed wildlife in public parks and open space because the animals usually pay the price.)
Some media sources also blame off-leash dogs for exacerbating the problem. The San Francisco Chronicle claims that off-leash dogs dig into the animals’ burrows, making them larger. There is a small, legal off-leash area in the center of the park. We have walked around the perimeter of this park many times. Although we have seen dogs being walked on-leash on the trail around the park, we have never seen an off-leash dog outside the legal off-leash area. Another media source reports that most of the burrowing animals live on the outer edge of the park which is consistent with our observation. Furthermore, making the burrows larger at the surface, doesn’t get them any closer to the clay cap two feet below the surface. Therefore, the scenario imagined by the Chronicle is not consistent with the facts. (1)
This project is similar to many others to which we object:
There is no evidence that there actually IS a problem. These animals should not be killed without such evidence.
IF there is a problem, it is one created by humans: We should have predicted the presence of burrowing animals when we closed this dump. An impenetrable cap on the garbage should have been installed. If an impenetrable cap was not physically possible, the garbage should have been removed. IF feeding the animals is contributing to the population surge, humans are the problem, not the animals. We do not assume that feeding the animals is, in fact, contributing to the problem. It sounds like more finger-pointing to us. (However, we agree that people should not feed wildlife in public parks because the wildlife usually pays the price for the pleasure of humans. We suggest that people channel that impulse into a sanctioned form of animal welfare such as volunteering in your local animal shelter or wildlife rescue organization.)
There is no evidence that dogs are contributing to the problem either. They are yet another scapegoat for a problem created by humans….IF, in fact, there IS a problem.
Humans have a very short-term perspective on nature. We often perceive problems in nature that are short-term and we over-react to them because we have a desire to control nature. In fact, surges in animal populations usually resolve themselves without our interference when the animals exhaust available resources. Humans often do more harm than good when we attempt to control nature and these attempts are usually futile because nature is far more powerful than we are.
We should set priorities when we address environmental issues. Untold thousands of chemicals are being drained into the bay every day according to the San Francisco Regional Water Quality Control Board: “’However, there are a number of chemicals that are showing up not too far from levels of concern, and that’s the bad news,’ said Tom Mumley. assistant executive officer of the San Francisco Regional Water Qaulity Control Board, ‘There’s a really big, long list of chemicals that we haven’t measured yet, or we don’t have good thresholds to interpret whether the concentrations out there are something to be alarmed about or not,’ said Jay Davis, a senior scientist at the San Francisco Estuary Institute. More than 100,000 chemicals are registered or approved for commercial use in the United States.” (2) While we merrily pour toxic chemicals down our drains and spray our public lands with pesticides, does it make any sense to worry about the POSSIBILITY that a few squirrels could be burrowing into a former garbage dump?
Update March 27, 2014: Berkeleyside (an excellent on-line news source for Berkeley) reports that the Berkeley City Council put the plan to kill ground squirrels and gophers at Cesar Chavez Park on hold indefinitely, pending further study. Berkeleyside reports that the Water Quality Board notified the City Council in writing that they did NOT order Berkeley to kill the animals, contrary to the claims of the Berkeley officials proposing the plan. There is absolutely NO doubt that this decision is a direct result of thousands of people contacting Berkeley to protest the plans. It pays to speak up, folks!
The swans of New York
Mute Swan. Creative Commons – Share Alike
The State of New York has announced its intention to exterminate all mute swans in the state. The mute swans were introduced in the 1880s because at that time people thought them beautiful. Now some people have apparently changed their minds. People calling themselves bird-advocates have decided that because mute swans aren’t native to the United States, they must be killed.
According to an op-ed in the New York Times,this bizarre plan to kill this and other non-native species of birds originates with the Audubon Society and other organizations advocating on behalf of birds (apologies for the contradiction). They succeeded in revising the Migratory Bird Act in 2004, to remove protections from all non-native birds in the United States. This policy was based on an ASSUMPTION that the mere existence of non-native birds is a threat to native birds. Like all similar projects to exterminate a non-native species, the State of New York provided no evidence that the mute swans are a threat to native birds. The proposal merely stated that the swans are “aggressive” and that they eat aquatic vegetation.
Since there are only about 2,200 mute swans in the State of New York, one wonders how much of a problem they could be. They are called “invasive,” as are most non-native species, but their small population suggests this is an exaggeration.
The comments on his op-ed about the swans are revealing. There is almost no support for killing the swans. Here is one of the few supporting comments from a typical nativist, using the usual arguments about how there MIGHT be a problem in the distant future: “Not-so-weird” says “A century is not nearly enough time for wetlands to adapt to the presence of a new species. Thousands or millions of years would be more appropriate. As we wait to see what happens, we could lose any number of native species whose ecosystem services we have yet to fully understand or appreciate. The science does not need to be complete for the safest, most responsible course of action to be removing mute swans from our wetlands in the most humane way possible.” It’s difficult to imagine our environment thousands or millions years from now, but we doubt that mute swans will be a concern in the unlikely event that there will be humans around to worry about them.
Don’t we have enough problems?
There is no shortage of real, serious problems in our environment. One wonders where our public servants find the time to dream up problems that don’t exist. We suggest that they put their over-active imaginations to rest and focus on solving existing problems rather than fabricating them. And while they’re at it, we would appreciate it if they would quit pointing fingers at animals when diagnosing problems most of which are caused by the actions of humans.
This is the story of the persecution of Tyrone Hayes, Professor of Biology at UC Berkeley, by the manufacturer (Syngenta) of an herbicide (atrazine). Professor Hayes was asked by Syngenta to conduct research on atrazine in 1999. Fifteen years later, New Yorker magazine has published a detailed account of Professor Hayes’ painful experience. (1)
Although Hayes was well aware of what Syngenta was doing to discredit him and his research, his suspicions have now been confirmed because of documents revealed by a legal battle. Specifically, 23 Midwestern cities sued Syngenta for “concealing atrazine’s true dangerous nature” and contaminating their water supply. The documents subpoenaed in those class-action suits revealed Syngenta’s campaign to undermine Professor Hayes’ credibility. In 2012, Syngenta settled those suits (without admitting wrongdoing) by giving $105 million to 1,000 water districts to filter atrazine from their drinking water.
Science for sale
Pacific Chorus Frog, Creative Commons
Professor Hayes has had an interest in frogs since he was a child in rural South Carolina. He was fascinated by the transformation from tadpole to frog. That childhood interest led to his primary research interest in amphibians. So, when Syngenta asked him to study the affect of atrazine on frogs, it seemed to be an opportunity to improve and expand his research program. Some of his graduate students were wary, but Hayes assured them that his work could not be compromised by the acceptance of the small fee ($125,000) from Syngenta.
It was not until Hayes and his team began to observe and report birth defects in the reproductive organs of frogs exposed to atrazine that he began to understand the risk he had taken in accepting that funding. His formerly collaborative relationship with Syngenta scientists quickly deteriorated when he reported his findings. He ended his formal relationship with Syngenta in November 2000, when it became apparent they were trying to prevent him from pursuing his research.
Then Syngenta began a relentless assault on his research and he, just as relentlessly, pursued his inquiries. While Syngenta hired other “scientists” to discredit his research, Hayes and his team traveled the Midwest to gather samples of contaminated water to analyze in his laboratory. They sent 300 pails of frozen water to Berkeley from Illinois, Iowa, Nebraska, and Wyoming. The more tests they conducted, the more evidence they found that atrazine caused profound deformities of the reproductive organs of frogs such as hermaphroditism which is the expression of both male and female organs resulting in sterility. These deformities were observed at atrazine concentrations 30 times less than allowed by the Environmental Protection Agency.
Dirty tricks
Here is an incomplete list of some of the things that Syngenta did to discredit Professor Hayes’ research. These activities were documented in the evidence subpoenaed during the atrazine suit.
Syngenta sent its employees to Hayes’ public presentations to ask rhetorical questions which cast doubt on the accuracy of his work, such as “Why can’t anyone replicate your research?” Hayes says the answer to that question is that no one has tried. Syngenta hired “scientists” who altered Hayes’ research methods and reported that their findings were evidence that replication was not possible.
Syngenta purchased search words on the internet so that any searches for Hayes’ research would send people to an advertisement that says “Tyrone Hayes Not Credible.” Ironically, Syngenta is now using that same tactic to discredit the article in the New Yorker. A search for “atrazine” sends the searcher to the “Atrazine Facts” website with leading articles attacking the veracity of the New Yorker article.
The work journal of Syngenta’s head of “communications” contained a list of plans to ruin Hayes’ reputation. One entry said, “set trap to entice him to sue.” Another entry said, “investigate wife.” Syngenta claims that some of the strategies on that list were not implemented.
The vast financial resources of Syngenta help to put these efforts into perspective. Syngenta’s sales of seeds and pesticides are worth $14 billion per year and atrazine sales are $500 million annually. They have the resources and the motivation to protect their product in the marketplace.
The evidence against atrazine mounts
Meanwhile, more scientists began to report evidence that atrazine causes birth defects. An epidemiologist reported that children conceived during the seasonal application of atrazine are statistically more likely to be born with genital defects. Shortly after the publication of that paper, the New York Times published a big study about the extent to which the nation’s drinking water is contaminated with atrazine. Both of these studies endured media attacks from Syngenta.
Jason Rohr, ecologist at University of South Florida and a member of the EPA panel which evaluated atrazine, criticized the “lucrative ‘science for hire’ industry.” He wrote for Policy Perspective that “…a Syngenta-funded review of the atrazine literature had arguably misrepresented more than fifty studies and made a hundred and forty-four inaccurate or misleading statements, of which 96.5% appeared to be favorable to Syngenta.” (1)
Two other members of the EPA scientific advisory panel for atrazine review have written a paper (not yet published) complaining that the recommendations of the panel are ignored and that the EPA is placing “human health and the environment at the mercy of the industry.” They conclude that“the single best predictor of whether or not the herbicide atrazine had a significant effect in a study was the funding source.” (1)
Getting away with it
Since Professor Hayes began to report the results of his study of the effects of atrazine on frogs there have been several reviews of atrazine by the Environmental Protection Agency. Hayes and other researchers participated in those reviews. The EPA has approved the continued use of atrazine after each review, most recently in 2012. The next review is scheduled for this year.
The European Union banned atrazine in 2003. The European Union uses the “Precautionary Principle” to evaluate pesticides for approval: “if an action or policy has a suspected risk of causing harm to the public or to the environment in the absence of scientific consensus that the action or policy is harmful, the burden of proof that it is not harmful falls on those taking an action.” (2) In other words, the manufacturer of the pesticide must prove it is NOT harmful. (Ironically, the city of San Francisco is legally obligated to use the Precautionary Principal for approved use of pesticides, although the city is using pesticides which the EPA considers “hazardous.”)
American federal law uses the opposite approach. The Environmental Protection Agency must prove that a pesticide is harmful before banning that product. The New Yorker explains in detail all of the legal limitations on the EPA in establishing such proof. For example, the EPA is legally obligated to involve the industry in establishing the criteria for the review. They are also legally obligated to conduct a cost-benefit analysis. Syngenta claims that corn production in the United States would be drastically reduced if atrazine were banned. Proving health and environmental consequences of continued atrazine use of equal economic value to corn production would be difficult.
These and other legal obstacles have rendered the EPA nearly impotent to regulate pesticides. While it may be tempting to blame the EPA, lawmakers are largely responsible for tying their hands. There are some 80,000 chemicals in the environment. The EPA has banned only 5 chemicals since its inception in the 1970s (PCBs, chlorofluorocarbons, dioxin, asbestos, and hexavalent chromium; the ban on asbestos was overturned in 1991 [2]).
Syngenta is now represented on the federal Invasive Species Advisory Committee, which puts them in a position to influence the country’s policies regarding the eradication of non-native species using their products. This seems to us a flagrant conflict of interest and a clear indication of the extent to which our government is controlled by industry. Such appointments are discretionary and therefore cannot be blamed on legal requirements. Rather they are more a reflection of the way money influences politics in our country.
The consequences
Atrazine is the second most widely used herbicide in the United States. Only glyphosate (Roundup etc.) is used more often. Atrazine degrades slowly in the soil and washes into streams and lakes where it does not dissolve. An estimated 30 million Americans are drinking water contaminated with trace amounts of atrazine.
Atrazine use 1997
To our knowledge, atrazine is not being used by any of the ecological “restorations” of the public lands in the Bay Area. Atrazine is used primarily—but not exclusively—for agricultural crops, most notably corn. In California, about 23,000 pounds of atrazine (active ingredient only) were used on over 1 million acres in 2011. (3)
The fragility of truth
We can empathize with Professor Hayes. Like him, we have been engaged in the effort to inform the public of the destruction of our public lands for 15 years. And like him, we have been on the receiving end of a campaign to discredit and intimidate us into abandoning our effort.
The February 6, 2014 meeting of the Integrated Pest Management Program in San Francisco provides a recent example. The director of San Francisco’s so-called Natural Areas Program told a roomful of her colleagues that criticism of her program’s herbicide use is “frankly nonsense.” Since our sources of information about herbicides are exclusively Material Safety Data Sheets mandated by the EPA and the manufacturers’ labels, we consider this statement groundless defamation. Admittedly, this is a trivial example, compared to the harassment endured by Professor Hayes. The analogy is that both are an attempt to discredit and dismiss critics of pesticide use.
Professor Hayes’ reaction to his experience is similar to ours. The more they attack him, the more determined he is to make his case. He has been vindicated by being promoted to full professor in 2003 and other researchers have reported similar findings in humans. Although he told the New Yorker that “the tide is turning,” atrazine is still on the market.
Likewise, we tenaciously pursue our mission to stop the destruction of our public lands. It is now clear that our opinion of these projects is shared by the public as well as many scientists. But we are not there yet.
We recently republished an article from the Garden Rant blog about the overuse and misuse of the word “invasive” to describe plants. That article objected to the exclusive use of that pejorative word to describe non-native plants, when native plants often behave in exactly the same way. The article also pointed out that the behavior of plants varies depending upon local conditions such that labeling any plant “invasive” beyond a specific locality is bound to be inaccurate.
A huge expanse of coyote brush at Lake Chabot, an example of a native plant that would be called “invasive” if it were not native.
Today we will tell our readers about a new study which explains why the word “invasive” is causing confusion.(1) Four scientists in Zurich, Switzerland conducted structured interviews with 26 academic invasion biologists and landscape professionals and found no consensus about the definition of “invasive.” Nor is there any agreement about the definition of “native,” which is surely contributing to the confusion about the appropriate use of the word “invasive.” Finally, the authors of the study compared this lack of consensus with the scientific literature of invasion biology. They found a conspicuous discrepancy between the uncertainty expressed in the interviews with experts and the conservation policies that are theoretically based on the scientific literature.
And the eucalyptus forest behind the coyote brush at Lake Chabot which is called “invasive” but in fact, rarely invades.
What is the difference between native and non-native species?
Although there was some agreement amongst invasion biologists that non-native species arrived with the help of humans, there was less agreement about the timing and location of arrival. Some said non-natives arrived after the last glacial period (about 10,000 years ago) and others said after 1500 A.D. (post-Columbian exchange). Landscape professionals were more likely to say that species are native which arrived prior to the life-span of humans, a significantly shorter period of time, obviously. This is consistent with the tendency for landscape professionals to consider human perception the source of such categorization.
There was little agreement about a spatial definition of native species. Some invasion biologists define native species within the context of political units (such as countries) while others use biogeographic definitions such as continents or on either side of a continental divide.
There is also disagreement about the means of movement used to define a species as non-native. Some invasion biologists consider species non-native if their range has changed as a result of climate change because of the anthropogenic origin of contemporary climate change. Such movement is now rapidly occurring so this particular definition is likely to result in the changed status of many species presently considered native, a change that is likely to make them targets for eradication.
When is a non-native species “invasive?”
There was little agreement about the criteria for calling a non-native species “invasive.” Some invasion biologists did not think that an “invasive” species need behave any differently than a native species to be categorized as “invasive.” Others believed it is appropriate to call a non-native species “invasive” if it spreads, even if that species has no negative impact on the ecosystem. When asked to evaluate the impact of non-native species, more invasion biologists and landscape professionals considered the impact “neutral” (56%) than those who considered the impact “negative” (32%). Invasion biologists tended to assess the affect of non-native species more negatively than landscape professionals.
The interviewees were then asked on what they based their judgment of the impact of non-native species. This is perhaps the most telling question of all. Both groups of experts lamented the absence of empirical evidence of the impact of non-native species: “In almost a third (32%) of all assessments, experts could not recall any effects of non-native invasive species on ecosystem services.” Most admitted that their judgment was based on “intuition” informed by their “general knowledge” or “extrapolating” from related knowledge: “most experts were prepared to assume that non-native invasive species have a generally negative effect upon native biodiversity.” (emphasis added)
Are non-native “invasive” species a serious problem?
This is the question for which the answers of invasion biologists and landscape professionals were most divergent. Invasion biologists consider non-native “invasive” species a serious problem which is underestimated by the public and politicians. In contrast, landscape professionals said the problem is overestimated: “…particularly due to anxiety and xenophobic feelings among the public.”
The consequences of this lack of clarity
The authors of this study then examined the publications of invasion biologists to see if this lack of consensus is apparent in the scientific literature of invasion biology. They observed that invasion biologists start their publications with a definition of non-native and invasive species, but “in the rest of the text this definition was rarely strictly applied.” They tend to use the terms “non-native” and “invasive” interchangeably. They compare the spreading of native species to non-native species without indicating that the native species is also invasive.
The authors conclude that both the categorization of species as native or non-native and their designation as “invasive” are largely value judgments that reflect cultural values, not scientific judgments. They suggest that invasion biologists “acknowledge the uncertainties and engage transparently with stakeholders and the public in deliberations about conflicting opinions. Here invasion biologists should take the role of ‘honest brokers of policy alternatives,’ taking into account different prevalent values and policy preferences rather than adopting the role of ‘issue advocates.’”
In other words, the conservation policies which are theoretically based on the scientific literature of invasion biology should acknowledge the uncertainty that pervades the discipline. Given that uncertainty, the value judgments of the public should be on an equal footing with the value judgments of those who have a vested interest in the projects that are destroying existing landscapes. There are alternatives to those destructive projects and the public’s opinion must be taken into account in considering those alternatives.
Of course, we agree. As we have said many times on Million Trees, invasion biology is not a scientific discipline. Rather it is a set of value judgments based on a belief that native species (whatever they are) are superior to non-native species. This is not just a question of semantics. Many species are being killed because of what someone chooses to call them and irreparable damage is being done to our environment in the process of killing them.
It’s not easy to find information about herbicide use by land managers. We make inquiries and public records requests of all the managers of public lands in the Bay Area. Despite these persistent efforts, we have never been confident that we have the complete picture. We are therefore grateful for a recent survey conducted by the California Invasive Plant Council (Cal-IPC) of land managers—public and private—about the methods they use and for what purposes. The following charts tell us what Cal-IPC learned from their survey.
Cal-IPC sent surveys to 100 land managers who described the lands they managed as follows:
Organization*
Response
Local agency
54%
Federal agency
53%
State agency
48%
Land trust or other private landowner
40%
Private consultant
26%
Other (nonprofit, forestry company, utility, regional park district, conservation district)
27%
*multiple employers
How frequently are the following objectives part of land managers’ reason for managing invasive plants?
Non-herbicidal methods used by land managers to control invasive plants
Method
Always
Frequently
Rarely
Never
Pulling with hand tools
9%
76%
14%
1%
Digging with hand tools
8%
64%
24%
4%
Cutting with pruners or loppers
7%
59%
27%
7%
Weed whacking with string or plastic blade
7%
52%
27%
14%
Cutting with hand saw or chainsaw
3%
52%
34%
10%
Mowing with large equipment
3%
44%
26%
27%
Brushcutting with metal blade
2%
30%
37%
30%
Grazing
0%
29%
23%
47%
How often do land managers use herbicides for invasive plant control?
What methods do land managers use to apply herbicides?
Method
Always
Frequently
Rarely
Never
Foliar spray – spray to wet
8%
69%
19%
4%
Foliar spray – thin line
1%
13%
30%
55%
Foliar spray – low volume/high concentration
1%
22%
35%
42%
Basel bark application
2%
17%
44%
37%
Cut stump application
4%
49%
35%
13%
Drill and inject application
1%
11%
30%
58%
Girdling or frilling application
1%
5%
43%
51%
Broadcast application
1%
23%
45%
31%
Wick application
2%
6%
44%
48%
Aerial application
0%
4%
13%
83%
What herbicides are used by land managers?
Active Ingredient
Response Percent
Glyphosate (e.g. RoundUp, Aquamaster)
99%
Triclopyr (e.g. Garlon 3A, 4A)
74%
Aminopyralid (e.g. Milestone, VM)
50%
Clopyralid (e.g. Transline, Reclaim)
45%
Imazapyr (Chopper, Stalker, Habitat, Arsenal)
42%
Chlorsulfuron (e.g. Telar)
31%
Fluazifop (e.g. Fusilade)
20%
2,4-D (e.g. Amine 4, Weedar)
12%
Acetic acid
6%
Clove oil (e.g. Matran
5%
Pelargonic acid (e.g. Scythe)
2%
These charts were shown by the Executive Director of the California Invasive Council (Cal-IPC) at a meeting of the Integrated Pest Management Program in San Francisco on February 6, 2014. He explained that the survey of land managers was conducted to assist Cal-IPC in preparation for a new edition of best management practices for managing invasive plant species in wildlands. That publication will include risk assessments of the herbicides being used by land managers. Cal-IPC is collaborating with the author of the risk assessments of potential herbicide use for the Marin Municipal Water District. We look forward to the publication of this document, which is anticipated in June 2014. We hope that land managers will have confidence in the risk assessments of the herbicides they use, given the source of the information.
We make note of …..
According to this survey of land managers:
Ninety-four percent of land managers are using herbicides to control plants they consider “invasive.” Sixty-two percent are using herbicides frequently.
Seventy-four percent of land managers are using Garlon, which is one of the most hazardous herbicides available on the market, as rated by the Environmental Protection Agency.
Many land managers are using Milestone and imazapyr which are known to be mobile in the soil as well as persistent in the environment according to the manufacturer’s label and the Environmental Protection Agency.
Foliar spray is the method used most frequently by land managers to apply herbicides. This method of application has the potential to drift into non-target areas.
These practices are not adequately acknowledged in the environmental impact reports for the ecological “restoration” projects in the Bay Area. Some environmental impact reports have not acknowledged the types of herbicides being used or the methods used to apply them. None of the reports have acknowledged the quantities used by the projects nor have they acknowledged the toxicity of the herbicides. The public is therefore unaware of the extent to which herbicides are being used by these projects and the risks associated with using them.
As our readers know, we consider climate change the most important environmental problem of the 21st century. All other environmental issues pale in comparison to climate change because most other problems are exacerbated, if not caused by climate change. For example, when native plant advocates demand that we destroy healthy trees storing tons of carbon dioxide, we know that they are not benefiting native plants which will be less well adapted to a changed climate. The many projects that are destroying healthy trees chip the wood, which releases the stored carbon into the atmosphere as carbon dioxide as the wood decays over time.
The environmental reviews of these destructive projects try to respond to this criticism of their projects by making a number of bogus claims. For example, they claim that they intend to replace all the trees with native trees, although the horticultural requirements of native trees will prevent their survival where most non-native trees now thrive. They also claim that the mythical new native trees will compensate for the loss of the carbon stored in the existing urban forest, based on their belief that young trees store carbon at a faster rate than old trees.
Now we have a new study which has overturned this assumption. Thirty-eight scientists from all over the world participated in a study of 670,000 trees from 403 tropical and temperate species of trees. They have reported their findings in Nature magazine:
“Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree’s total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density.” (1)
In other words, we now have empirical evidence that large, old trees store far more carbon than young trees.
The impact of climate change on birds
Since native plant advocates often claim that their destructive projects benefit birds, let’s examine that claim in the context of climate change. How is climate change making life difficult for birds? That’s our topic today.
Female Snowy Owl. Creative Commons
We start with a report that snowy owls are being seen in the continental United States, in places far outside their normal range, such as Little Rock, Arkansas and northern Florida. At Logan Airport in Boston, more than 75 snowies have been captured and relocated during last fall’s migration season, an unprecedented number. Airports are attractive to grass-eating birds such as geese as well as raptors hunting for small mammals, such as owls and hawks because they are surrounded by vast, open fields. Airports are dangerous places for both birds and airplane passengers, so this isn’t good news for anyone.
Snowy owls are enormous birds (20-27 inches tall and 54-66 inches wingspan) with white feathers that blend with their usual home in the Arctic. So what are they doing so far south? Nobody really knows, but there are theories. One of those theories is that there was a sudden surge in the population of lemmings in the Arctic which is the preferred prey of the snowies. That sudden increase in their food source may have caused a surge in the population of snowies and now they must disperse to parts unknown to find what they need to eat. We will revisit that theory latter in the context of climate change; the article about the impact of climate change on bird populations (see below) reports that the population of lemmings has declined, suggesting that the snowies are moving south in search of food.
What happens when snow turns to rain?
As the climate warms, places where winters brought snow in the past are now rainy. Think of what that means to birds sitting on nests in the open. Snow doesn’t penetrate the down of chicks as much as rain does. A nestling that was kept dry in the snow is now soaked to the skin. Brrrrrrr…can you feel for that bird?
Magellanic Penguin. Creative Commons
A colony of Magellanic penguins in Argentina has been studied for decades by a researcher who now reports that climate change is taking its toll on that colony:
“’Rainfall is killing a lot of penguins, and so is heat,’ said P. Dee Boersma, a University of Washington scientist and lead author of the study, ’And those are two new causes.’” (2)
The penguin chicks are most vulnerable about a week after hatching, when their parents have quit protecting them round-the-clock. After about 6 weeks, they develop more waterproof plumage. In the past, only about one-third of chicks survived to leave the nest, most often as a result of predation and starvation. Heavy storms killed penguins in 13 of the 28 years of the study. Extreme heat events have recently taken a toll. The population of breeding pairs in the colony has declined by 24 percent since 1987.
Rain where snow was the more usual winter weather-pattern is also known to have taken a toll on the peregrine falcon population in the Canadian Arctic.
Disrupting the food chain in the Arctic
Yale Environment 360 recently published a report about the impact of climate change on birds in the Arctic. (3) Here is a long, depressing list of specific impacts on many species of birds as a result of climate change in the Arctic:
The rising temperature in the Arctic has increased the population of mosquitoes. Some birds are dying from blood loss. This may be hard to imagine if you haven’t visited the Arctic. We can tell you from experience, that the air is black with mosquitoes on a typical summer day in Alaska.
Contrary to the opinion of the researchers studying snowy owls, the researchers interviewed by Yale Environment 360 say that the population of lemmings and other prey has declined which has reduced populations of peregrine falcon, ptarmigan, jaeger, skua, etc. A researcher explains that early, deep snow provides the insulation needed for successful breeding of lemmings. Without this insulation, the population has decreased significantly.
As spring arrives earlier, snowshoe hares may not be changing their white fur fast enough to escape predation, which will reduce that population over time as fewer hares survive to breed in the future. The hare is an important source of prey for the raptors.
Gulls scavenged the seal hunts of polar bears in the past. With receding ice and reduced hunting opportunities, this food source has decreased and what remains is often contaminated with mercury. These factors have combined to result in an 80% decline in the gull population since the 1980s.
When weather conditions are unseasonal and extreme at the start of the nesting season, birds often skip the nesting season altogether. Such a sensible choice has been observed by scientists in several locations.
The article ends on a modest note, by reminding us how little we know about birds and the limitations of the research that is done on their populations. Some of the population changes that have been observed could be short-term. There is much variation in nature from which we cannot accurately extrapolate.
How could local native plant “restorations” benefit birds?
The projects demanded by native plant advocates will destroy tens of thousands of healthy, old, large trees that are expected to live at least 200 more years and store much additional carbon during that period. These trees will release tons of the greenhouse gases causing climate change when they are destroyed. Climate change is clearly not benefiting birds. How can native plant advocates continue to claim that the projects they demand will benefit birds? It is a cruel fiction that these projects will benefit birds.
We are reporting about studies of birds in polar regions today. Climate change at the poles is presently more visible and extreme than it is locally. Assuming that we continue to do nothing, we can expect similar changes in our neighborhood in the near future with similar impacts on the birds.
Conservation Sense and Nonsense 