National Geographic

The Threat of Invasive Species—An Interview with Dr. Michael Hutchins

Feral pig

In an ongoing series of interviews with renowned wildlife professional and ecologist Dr. Michael Hutchins, Newswatch Contributing Editor Dr. Jordan Schaul explores another threat to nature.

In the last interview Michael and Jordan discussed the Nature Deficit Disorder.

Here is a complete bio for Dr. Michael Hutchins.


Jordan: People, including scientists, often confuse or misuse terminology applied to invasive species biology.  For example, the words “exotic”, “non-indigenous” and “introduced” are used interchangeably, but their precise meaning usually warrants more conservative usage.  The distinctions may seem trivial, but they are important in helping us understand how these “invaders” influence the world around us. Can you first provide some background information on invasive species with particular regard for the labels and terminology?

Michael:  There are a few subtleties in definitions. The terms “exotic”, “alien”, “non-indigenous” and “introduced” are often used interchangeably to describe species that are non-native to a host ecosystem.  More specifically, they refer to species that have not evolved in the host ecosystem, or naturally colonized the area; but rather, to species that have been actively transported by humans past natural geographical barriers to dispersal (e.g., mountain ranges, oceans, rivers, etc.). Introductions can be either purposeful or accidental. Examples of purposeful introductions (i.e., those in which humans consciously decided to move animals from one place to another) include the nutria in the southeastern United States, the mongoose in Hawaii, and the European red deer and Himalayan tahr in New Zealand. Accidental introductions (i.e., those that were moved without human knowledge) include the brown tree snake on Guam, which arrived on ships from Australia or New Guinea during World War II and European rats and mice, which also caught a ride on sailing ships during the colonization of North America. Of course, not all introduced species are invasive. A species becomes invasive when it successfully establishes itself within a host ecosystem subsequent to its introduction.

That being said, climate change may necessitate some re-evaluation of this terminology. Climate (e.g. temperature, rainfall, etc.), which has in the past, limited the dispersal and subsequent colonization of some areas by some species, may not be a barrier in the future. Thus, we may see unexpected movements of some flora and fauna into areas that were previously uninhabited by them. Climate change is a human-made phenomenon, so this may not technically be classified as a “natural” colonization or change in distribution; however, since the organisms are moving on their own, it is still different from the human-caused purposeful or accidental species introductions across natural geographical barriers to dispersal.

One of the most commonly misused terms in our vocabulary is the term “feral”. By the term “feral” we are referring specifically to domesticated animals (i.e., those that have been shaped by many generations of selective breeding) that have “gone wild” and are no longer living under human care.  Examples would include feral cattle, pigs, goats, sheep, horses, cats and dogs.  Feral animals are not considered “native” to their host ecosystems; however, their ancient progenitors can be (e.g. feral horses are not native in North America, nor are domesticated cats in Africa). Feral rats, cats and pigs are especially serious pests.

Jordan: In Anchorage, where I lived most recently, there is great concern for the impact northern pike have on trout and salmon populations. There is also considerable concern for a plant invader that we are all familiar with—purple loostrife. But we often forget the economic toll that results from not only the direct impact invaders and introduced species have on native flora and fauna, but the efforts to manage these populations of “invasive” species are also quite costly. What are your thoughts?

Michael:  Yes, the financial cost of either eradicating or controlling introduced species is enormous. It is estimated that the United States Department of the Interior alone spends over $100 million annually on the management of the most destructive of these ecological interlopers.  Of course, these expenditures must be weighed against the monetary and biological costs of inaction. It is estimated that introduced species are costing the U.S. $120 billion annually in lost crops, property damage, environmental degradation, etc. (Pimental, D., Lavch, R. and Morrison, D. 2000. Environmental and economic costs of non-indigenous species in the United States. BioScience 50: 53-65).  This is why it is so critical for our nation to enact effective legislation that prevents additional introductions of destructive non-native flora and fauna before they occur.  Some legislation currently exists to deal with specific circumstances (; however, existing laws are simply not sufficient.  Currently, U.S. law is weak and our government has been slow to act. There is legislation pending, but it sits languishing in Congress (

Jordan: The management of feral cats in North America has generated contentious debate among a number of factions, including conservation scientists and activist communities. Is there an easy answer?

Michael: No, there is no easy answer, primarily because of the human dimensions creating this growing ecological problem (Lepczyk, C.A., van Heezik, Y. and Cooper, R.J. 2011). An issue with all-too-human dimensions. The Wildlife Professional 5(1): 68-70).  First, it is important to point out that domestic cats are a non-native species.  No one knows for sure, but there are an estimated 30-80 million feral domestic cats in the United States.  Add to that the number of house cats that are allowed outdoors and we are talking about tens of millions more.

A battle is ongoing between feral cat advocates and conservationists over how to address this issue.  Cat advocates, represented by organizations, such as Alley Cat Allies, Best Friends Animal Society and the Humane Society of the United States, believe that the answer to feral cat control is Trap-Neuter-Release (TNR) programs. Such programs consist of “managed” cat colonies, where the animals are trapped, sterilized, vaccinated against rabies (in some areas) and then released back into the environment, ranging from natural areas to suburban and urban neighborhoods.  Colony managers provision the cats with food and sometimes protect them from predation by building structures onto which they can escape. Cat advocacy groups have sold TNR as an effective way to control feral cat populations to a growing number of municipalities around the country.  In fact, there is a movement in the U.S. to stop accepting stray and feral cats at shelters, to treat feral cats as protected wildlife, and to prevent private landowners from controlling feral cats on their properties.  Under this scenario, shelters simply become revolving doors back into outdoor colonies.

So why do conservationists oppose TNR? First, domestic cats—even well-fed ones—are deadly predators, which are killing an estimated 1 billion birds and other small native animals annually.  These numbers are extrapolated from studies that looked at the number of prey animals that were brought home by outdoor house cats.  More recently, cat predation has been investigated by radio-tagging birds and monitoring cats with “Kittycams”, small video cameras mounted on the animals to track their activities (;  Predation by feral and free-roaming house cats has caused the extinction of endemic island bird species (Dauphine, N. and Cooper, R.J. 2011. Pick one: Outdoor cats or conservation. The Wildlife Professional 5(1): 50-56.), and when eliminated from oceanic islands, native birds have made dramatic comebacks (  Furthermore, when systematic studies have been conducted, TNR does not appear to be an effective method of controlling feral cat populations, primarily because of immigration into colonies or a failure to sterilize a sufficient percentage of the cats ( Some of these managed colonies have been active for more than 20 years and artificial feeding of the animals likely increases the longevity of the cats. Unfortunately, municipalities that do implement TNR-only management do not require independent evaluation of such projects to ensure that the number of cats is declining as a result.  In fact, the goal appears not to reduce feral cat numbers, but to simply avoid euthanasia.

Predation on a passerine by a feral cat

The diseases associated with feral cats are also problematic. The numbers of rabies cases in feral cats appear to be increasing, with new reports almost weekly (  Rabies is not the only zoonotic disease carried by feral cats; others include typhus and hookworm (Gerhold, R. 2011. Cats as carriers of disease. The Wildlife Professional 5(1): 58-61).  Among the most dangerous and underrated of these is Toxoplasma gondii, a protozoan that must pass through the gut of a cat to reproduce, which has, as an acute disease at the time of infection, been linked to fetal deformities and death in humans (  Once acquired, toxoplasmosis is chronic infection, which has recently been linked to autism, schizophrenia and even brain cancer in humans (;;  While some of these studies are correlational and thus do not imply causation, they are suggestive.  Even more remarkable is that T. gondii is a parasite that may manipulate the behavior of its host.  Rodents that carry the protozoan lose their fear of cat urine, which would normally cause them to flee, thus increasing the probability that they will end up in the gut of a cat; this may have some implications for human behavior as well (  T. gondii coming from freshwater  run-off from cat litter in land-fills and feral cat colonies near our coasts has resulted in the death of thousands of marine mammals, including dolphins, whales, seals, sea lions, and sea otters. (;  The connection to marine mammals may be through their diets: anchovies for seals, sea lions, whales and dolphins ( and for sea otters, through filter feeding mollusks (  Feline leukemia, a disease common to domestic cats, is a problem for the endangered Florida panther (

Remarkably, even with all of this evidence, cat advocacy groups continue to claim that the animals have little impact on native wildlife, that they are not significant carriers of disease and that TNR is the most and only effective way to manage feral cat populations (;!/2012/03/bird-lobby-still-conspiring-against.html).  Then why have several conservation organizations and scientific societies, including The Wildlife Society, National Audubon Society, the American Bird Conservancy, the American Association of Wildlife Veterinarians, the American Society of Mammalogists, and the National Wildlife Federation, developed policies that oppose the practice?  (e.g., Unfortunately, we know full well that even when presented with contradictory evidence, many people have a very difficult time changing their world view ( and the values of cat advocates and conservationists are very different. While the former are focused solely on the lives and welfare of individual cats, the latter are generally concerned about animal welfare and the survival of native wildlife populations and their habitats.  What is fascinating and paradoxical, however, is that the welfare of domestic cats is not improved by allowing them to roam free.  Outdoor cats are hit by cars, contract diseases, and are killed by predators. One study found that 42% of the items consumed by 8 coyotes living in Tucson, AZ, over a 5-month period were domestic cats (  Even People for the Ethical Treatment of Animals (PETA), among the most strident of animal rights organizations, opposes TNR management for feral cats based on humane considerations (

So what are the potential solutions? There are many things that could be done immediately to address this growing ecological problem, the root of which is irresponsible pet ownership.  The first thing would be to establish required pet owner education programs, which stress the problems associated with cats going outdoors.  Second, pet cats should be licensed, sterilized and banned from roaming without supervision, and the fines for violations should be substantial.  Third, there should be a limit on the number of cats that can be maintained per household.  Fourth, there should be a ban of feeding feral cats and as many feral cats as possible should be taken out of the environment through live trapping and removal.  Feral dogs can also pose a serious problem for wildlife (  However, we have rules against dogs being allowed to be off leash or roaming without supervision, so why not cats?  Last but not least, feral cats should immediately be removed from all island ecosystems, or other environmentally-sensitive areas, such as wildlife refuges or parks.

To help resolve this contentious issue, it is critical that state and federal government agencies get involved in the debate.  State fish and wildlife agencies and the U.S. Fish and Wildlife Service have a legal and moral obligation to protect our native wildlife (  Similarly the Public Health Service and the Centers for Disease Control have a responsibility to protect public health. Decisions to engage in TNR are being made by local politicians who have little or no knowledge about the situation, are only told one side of the story, or are just taking the easy way out. However, some municipal and company leaders have stood up to the feral cat lobby and either rejected or discontinued TNR when they discovered that it was not doing the job that it was intended to do (;;;;

Jordan: Recently, some ecologists have argued that we should begin to accept the fact that many exotic species are here to stay, not all exotics are destructive, and some could be beneficial. Further, they suggest that some ecologists are prejudiced against exotics and we should just accept the” new normal.” What do you think about that?

Michael:  This is unfortunately true. Some ecologists have apparently conceded defeat in our battle with invasive wildlife and plants, declaring exotic species the winners. For example, Mark Davis of Macalester College in St. Paul, Minnesota, and his colleagues have suggested that it will be a “never ending battle to keep a habitat pure.” They contend that non-native species are really not all that bad and that we should take a new approach to the fast-blending biosphere or so-called “Anthropocene” (proposed term for the present geological epoch—from the time of the Industrial Revolution onwards—during which humanity has begun to have a significant impact on the environment) (  As Davis et al. have said, “We should accept this coming change as inevitable and simply begin managing for what is desirable and undesirable, not for what is ‘natural.’  There certainly are some introduced species that are beneficial, including our domesticated food crops.  However, it has also been estimated that some 80% of introductions have been detrimental, thus earning them the term “biological pollution.”  Consequently, the vast majority of biologists and ecologists believe that the views expressed by Davis et al. to be counterproductive (Simberloff, D. 2012. There’s nothing benign about invasions. The Wildlife Professional 6(2): 39).  Ignoring these growing problems, they say, will greatly reduce our future options and result in the extinction of many native species, including those of great ecological and cultural importance (see below).

There is no doubt that it will be difficult to control or eradicate some invasive species once they have become established.  However, it is critical that the most destructive of invasive species be targeted for action, and that new technologies are developed to get the job done and added to the already-existing arsenal ( The U.S. government is taking this issue very seriously.  A new bill, HR 669, the “Non-native Wildlife Prevention Act”, introduced into Congress in 2009, seeks to classify all imported species as to their probability of becoming invasive, and to ban the importation of all species deemed a significant threat.  Additional steps are being taken to build governmental capacity to prevent the introduction of invasive species at our borders and other points of entry. A recent study published by IUCN-The World Conservation Union, identified trade and travel as the “primary drivers of biological invasion, both into and out of the United States” and determined prevention measures to be “the most cost effective means of minimizing the introduction of and thus impact of invasive species” (

Jordan: What kind of impact can invasive species have on human health?

Michael: There are many potential impacts of introduced species on human health. Introduced species are not just limited to larger animals and plants; they can include pathogens as well.  Who can forget the introduction of smallpox to the New World and its devastating impact on Native American cultures?  Perhaps the best known of recent introductions to the United States is the West Nile Virus, a pathogen spread by mosquitoes that has killed millions of native birds, but also afflicts humans (  In fact, a potential new disease vector, the Asian tiger mosquito, was imported accidentally to the U.S. in tire casings intended for recapping. The insect carries and transmits many diseases in its native range (  Introduced vertebrates are carriers of potentially dangerous diseases (see comments on feral cats, above).  For example, feral swine carry brucellosis, a potentially serious disease that can be passed to humans, domestic animals, and wildlife (;

Jordan: I’m most interested in the future of wildlife conservation.  Can you talk about the threats to biodiversity and global species preservation in the context of invasive species biology?

Michael: The introduction of non-native species has had a devastating impact on North America’s native fauna and flora and their habitats (  Of the nearly 2,000 imperiled species in the United States, close to one half are endangered due to the impact of invasive species. It is important to note that many anthropogenic factors have contributed to the decline of our native fauna and flora (e.g., habitat loss, pollution, etc.), but these impacts are cumulative. Thus, alien species, working in concert with many other factors, are driving many native animals to the brink of extinction. In fact, introduced species have been identified as a greater threat to our native biodiversity than pollution, over-harvest and disease combined.

The effects of invasive species on native wildlife, plants and their habitats vary widely.  For example, introduced animals often compete with native species that have similar dietary needs. Introduced carnivores may prey on native animals, whereas herbivores frequently alter the composition of native plant communities, or reduce vegetative cover so that native wildlife becomes more susceptible to predation.  Exotic plant species compete with native ones for space and light and can crowd natives out of their own habitats. New and sometimes deadly diseases carried by alien interlopers have sometimes swept through indigenous populations.  In cases where the introduced species is closely related to a native species, interbreeding can alter the genetic composition of the native populations and decrease their survivability.  A failure to eradicate or control the most destructive of alien species is therefore likely to result in the widespread extinction of many native animals and plants.  Is this the heritage we want to leave our children and grandchildren?

Jordan: Does the public have a role in helping to control invasive species?

Michael:  There are a number of things the public can do to assist in controlling destructive non-native species and preventing future introductions.  In the case of invasive vertebrates, members of the public can inform state or federal wildlife authorities when they spot strange or unusual animals in their neighborhoods or in local parks. Often the first step in eradication or control is identifying that a non-native animal is present.  The invasive snakehead fish, a species native to Asia, was first detected by the public who caught the species while fishing (  Last, but not least, responsible people, who own pet cats and dogs can keep the animals indoors or under their supervision at all times and have them sterilized so that they cannot reproduce.  Similarly, people who have exotic reptiles, amphibians or fish, should not release them into nature, as these can be a source of species introductions.  The public can also become involved by contacting their elected representatives and expressing concern about invasive species and the many ecological problems they cause.

Jordan: Yes, exotic fish can have a devastating impact on aquatic ecosystems. Farmed exotic species for food consumption can present potential hazards, but so do aquarium fish sold to aquarium hobbyists, as you mentioned.  I recently addressed this in a recent post highlighting the work being done by the Shedd Aquarium and its partners to address exotic species introduced to the Great Lakes Ecosystem (

Removal of invasive vegetation by students

I’m glad you mention citizen involvement.  There are many opportunities out there for people to learn about invasive species so that they can participate in efforts to control or eradicate them. Here at the Orange County Zoo, we display native animals from the region. My hope is that we can select some invasive species for display as other natural history institutions have done.  The more the public knows about invasive animals, the more we can curb the growth of those that are deemed most damaging to our native ecosystems.  What about invasive plant species?

Michael: In the case of invasive plants, many schools, gardening clubs, conservation organizations, citizen science programs, and zoos and aquariums, have programs that allow the public to get directly involved in invasive plant control. For example, David Havens, a teacher at St. Luke’s School in New Canaan, CT—a member of the Green Schools Alliance (—designed and taught a high school course in environmental research, which engaged students in invasive plant removal.   This is a great way to get students outdoors, to familiarize them with identification of both non-native and native plants, and to get them directly involved in conservation.


  1. Michael Hutchins
    Washington, DC
    May 20, 2013, 4:36 am

    In reviewing the responses of animal activists to my science-based discussion of invasive species, I am reminded of a cartoon I recently posted on my Facebook page. It shows a television or radio reporter interviewing two individuals. He says, “…so we’ll be talking to a Dr. Jenkins at the National Institutes of Health about the results of his 3 year study. And then for a different take we’ll talk to Roger here, who I understand has reached the opposite conclusion just by sitting on the couch and speculating.” Funny, but also a sad commentary on the state of affairs in our post-modern world. With the advent of the Internet, suddenly everyone is an expert, regardless of their academic background or level of competence. That is certainly the case for feral cat and feral horse activists, who would now like to convince us all that these domesticated, feral, non-native animals should now be considered “native” to North America. I have likened their denial of the scientific evidence against their views to climate change and evolution deniers. The exclusive focus of these activists on their pet species is to the detriment of our native species and to human and animal health. Their response, in return, is to engage in personal attacks or attempts to call into question the expertise of those who oppose them. This, of course, is the first rule of propaganda. If your viewpoint is not supported by the evidence, then make some up, cherry pick only those findings that support your point of view, or call into question the motives or expertise of the opposition. That is exactly what animal activists are doing and it is to the detriment of our native wildlife, their habitats, and to human and animal health. In many cases, it is also of detrimental to the animals of interest themselves, who die early and cruel deaths from starvation, drought, disease, predation and collisions with vehicles. The fact is that animal populations must often be controlled, especially in a world dominated by human influences. I note that the strongest responses to these necessary management actions primarily involves animals that are popular pets, but which have adopted a feral lifestyle in the absence of human care. Often referred to as “petishism” this is a phenomenon of our modern culture. We spend billions of dollars on our pet cats and dogs, when many wild felids and canids, such as tigers, lions, and maned wolves are threatened with irreversible extinction. We deplete the ocean of fish, convert thousands of acres of land to crops, and kill thousands of other domestic animals to feed our pampered pets. Yet, when scientists question these unsustainable and ecologically destructive practices, they are labelled cat or horse “haters, or derided as biased or having a lack of expertise. I like cats and dogs and have had many as pets and I love to go horse back riding as well; I just don’t like what these animals do when they are allowed to roam freely and to breed uncontrollably in the absence of human care. Our planet is in dire straights and we are entering a time of great ecological peril. If we do not change our attitudes and behavior on a number of issues, we are going to lose many species, including some of great economic and cultural significance. It is ironic that people like myself who express concern about the current state of affairs and whom have dedicated their lives to wildlife science and conservation are either demonized, trivialized, or misrepresented by animal activists, who themselves, are so narrowly focused on their specific “objects of interest” that they cannot see the forest for the trees.

  2. Christie Finn
    May 20, 2013, 1:17 am

    Dr. Michael Hutchins’ testimony to support the Fish Wildlife Service on Arpil 7, 2011 in the House Subcommittee for Oceans, Fisheries, and Insular Affairs on North Carolina’s wild horses as an invasive, non-native, exotic, pest, feral, alien species (prevent, control, eradicate) and his subsequent blog April 8, 2011, “The perils of speaking truth about feral cats and horses” should disqualify him from forever being interviewed as a scientific expert for anything. Here you have an alleged scientist claiming that the horse, Equus caballus, that evolved in North America and nowhere is a non-native, invasive, exotic, feral, pest. He did omit the world alien, but alien is what tied cats and horses and the intent to eradicate both in the wild. Horses are being genetically collapsed by the four federal land management agencies as a non-native species even though this has been their evolutionary home through millennia. Dr. Hutchins is no scientist,

  3. frank poopcheek
    May 17, 2013, 2:09 pm

    belleh button eat it!

  4. Matt Chew
    December 31, 2012, 12:35 pm

    The old rules of biogeography weren’t rules, they were just practical realities. Practical realities change. What hasn’t changed is that what ‘belongs’ anywhere in particular depends on whether it arrives, then survives and reproduces under locally prevailing conditions.

    The ‘currents’ of today’s globalized commerce (the constant intercontinental, inter-hemispheric flow of materials, people and products) entrain all manner of organisms, entailing a new and constantly renewing re-dispersal of biota.

    Nature exhibits a kind of inertial conservatism, but it isn’t nostalgic. Nor is it moral, merciful, just, fair or forward-looking. Whether any population was ‘here’ last week or last year doesn’t matter. Whether it will be there next week or next year doesn’t matter, either, and never has. Darwinian ‘fitness’ always happens now, at the individual level. There are variations on that theme, but no exemptions.

    So far, the common human response to unlooked-for biotic redistribution has been misoneism and xenophobia. Even the most elaborate attempts to rationalize those reflexive sentiments have been absurd. Despite the premises of ‘invasion biology’ species can’t invade. Most of the organisms labeled ‘invasive’ have no way of knowing where they are, much less of formulating a shared intention of ‘taking over’. And we exempt from critique those that have most effectively excluded ‘biodiversity’ from vast areas (e.g., corn, wheat, soybeans, and cotton) because they have done so to our advantage and via our cooperative effort.

    Ecosystem managers — including farmers and gardeners — seek to affect biogeography by suppressing or subsidizing the fitness of particular populations. They choose the floras and faunas of their desire based on personal advantage, whether it be to minimize dismay or maximize aesthetic or economic values. But it is obvious that yesterday’s ecological assemblages are incompatible with new societies and economies. Embracing novel technologies and lifestyles while condemning their corollary novel ecosystems is, in a word, unsustainable.

  5. Louise Holton
    Mt. Rainier, Maryland
    December 28, 2012, 2:30 pm

    Despite cats being America’s favorite companion animal and millions of compassionate people feeding the nations’ outdoor cat population and sterilizing them at their own expense, National Geographic once again allows cats to be portrayed in a negative light in this “interview” with Michael Hutchins. Michael is of course well known for his dislike of cats, and for always rushing in to spread any negative information he can find about cats, as well as ignoring anything positive that is ever published.
    The decline in bird populations is caused by many factors. The main one being habitat loss. In fact a report by David I. King of the U.S. Forest Service’s Northeastern Research Station and John H. Rappole of the Smithsonian Conservation and Research Center concluded that the biggest threat to birds is the loss of the birds’ winter habitat in the tropics due to deforestation.
    We care about all animals, birds included, and need to find real solutions that everyone will be comfortable with and will support. It is clear to me working in this field for the last 22 years that people have overwhelmingly embraced nonlethal control for feral cats, and will NOT support killing. Trying to kill all the feral cats on a continent is going to be an impossible task. Even on islands it takes many, many years to achieve eradication and scientists have to use various methods including poisoning, shooting, and killing with feline viruses such as distemper.
    We also see in the aftermath of these “successful” killing of cats on islands that the rabbit, rat and mice populations started breeding out of control without cat predators, damaging the environment and bird populations—the very reason given for removing the cats in the first place.
    Many studies and many scientists have for decades found that cats were NOT to blame for declining bird populations. These are just a few examples:
    Errington, Paul L., 1936
    Notes on food habits of southern Wisconsin house cats. Journal of Mammalogy 17:64-65
    “Preying upon a species is not necessarily synonymous with controlling it or even influencing its numbers to any perceptible degree. Predation which merely removed an exposed prey surplus that is naturally doomed is entirely different from predation the weight of which is instrumental in forcing down prey populations or in holding them at given approximate levels”
    Coman, Brian J., and Hans Brunner, 1972
    Food Habits of the Feral House Cat in Victoria. Journal of Wildlife Management 36 (3): 848-853
    “Most references to predation by feral cats are unsupported by factual data” (848); “The common belief that feral cats are serious predators of birds is apparently without basis” (852-3)
    Mead, C.J., 1982
    Biologist Chris Mead “found no evidence that cats are impacting overall bird populations”
    Tabor, Roger, 1993
    Tabor found that “cats have low success as bird hunters”, and “the bulk of a feral cat’s diet is garbage, plants, insects, and other scavenger material” and therefore cats are “not impacting bird populations on the continents”
    It’s really way past time that Hutchins and his fellow anti-cat people stop scapegoating cats, help us get feral cats sterilized, and work on the real issues impacting birds and wildlife.
    Killing all the cats in the world will NOT save the birds—this is just a deceptive ploy used by those who hate cats and use scare tactics to justify the killing.
    In the past 200 years we have turned vast landscapes into parking lots, built enormous industries that have caused great environmental damage, created vast sprawling cities, and ignored the consequences to nature, wildlife and birds. Humans have a miserable record as far as degrading the land and using up scarce resources. Today and in the future we will be paying a high price for ignoring the issues of over-consumption.
    Birds are considered an indicator species for the environment, and there is no doubt that their numbers are in decline. “Birds…are dying from many causes, including natural ones. The fact is more than half the population of most bird species die every year. At least 100 million birds die every year from crashing into windows, scientists estimate. But windows, cats, West Nile virus, wind turbines — all those specific causes of death that are apparent in people’s backyards — are not, at present, having any known effect on the population size of any continental bird species,” says Research Scientist, John Rappole, Ph.D

  6. Karen Fishler
    United States
    December 27, 2012, 7:28 pm

    I assume that NG will, in the next few days, publish a lengthy interview with the president of Alley Cat Allies, Becky Robinson.

    In this interview, NG will accept every statement made by Robinson without debate, and will in fact make clear, by the wording of its questions, that it agrees with everything she is saying about outdoor cats.

    Because we know that NG is a fair, balanced, clear-thinking, objective organization that consults all authorities rather than taking the word of a man who promotes a method never shown to work. NG would never endorse the pointless cruelty of a 19th-century approach to living beings.

    NG would never do such a thing. Would it?

  7. Walter Lamb
    Culver City, CA
    December 27, 2012, 11:38 am

    While I appreciate Dr. Hutchins’ concern regarding invasive species in general, and his desire to minimize the impact of free-roaming cats in particular, it is painfully obvious from all of his past writings that he sees this as an ideological crusade, not an issue deserving of sound and objective science that can guide practical and effective policy. He once calculated that cats kill a minimum of 6.2 billion birds in North America annually (a figure that defies all mathematical sense given overall populations). He has defended an economic impact estimate that completely ignores the most basic economic principles and the realities of bird related economic activity. He refers to anyone who even considers sterilize and return programs as “wild bird executioners” and likens the practice to shooting wild birds with shotguns, regardless of whether a particular program achieved a population decline. He also makes no effort at side by side comparisons of lethal and non-lethal control, ignoring the reality that non-lethal control is often considered only after lethal control has proven ineffective in a particular setting.

    This morality-based approach, in which scientific sloppiness is considered justified if it furthers an ideological agenda, is the last thing our imperiled planet needs right now. We need folks like Dr. Hutchins to take a step back from their own emotional connection to this issue and recommit themselves to providing the sound and objective science that communities across the country need to develop practical policies. This is true also of many cat advocacy organizations and activists, who certainly need to inject a far greater level of accountability into their protocols.

    Most importantly, the media must do a better job not only with regard to this issue, but all of the many issues we face. To see National Geographic fall so short of their basic journalistic responsibility is truly disheartening. I have often given my nieces gift subscriptions and would like to do the same for my daughter when she is older. I would like to think that they would be challenged to actually think through issues and see that asking hard questions is a critical part of the scientific process. I do not want them to think that science is nothing more than someone’s passionate opinion.

    If the past is any indication, the author of this piece is already busy working on the next round of content and is probably only interested in the number of hits that this piece is generating. It is probably unrealistic to think that the author will take the opportunity to provide a real public service and delve into the complexity of this issue and challenge both critics and supporters of non-lethal control to defend the claims that they are making.

  8. Peter J. Wolf
    Phoenix, AZ
    December 26, 2012, 3:12 pm

    Might I suggest that this is, contrary to what’s suggested in the article’s title, no interview at all, but an easy opportunity for Hutchins to repeat the same flawed “arguments” he’s made for years on his blog for The Wildlife Society? Had this been an actual interview, there would have been insightful follow-up questions—one of the most obvious being: How would restrictions or outright bans on trap-neuter-return (TNR) benefit the wildlife Hutchins claims to want to protect?

    Hutchins makes several references to “evidence,” but fails to cite even a single case where large-scale eradication efforts have been effective. (And he never discusses the enormous costs that would be involved.)

    And, as he’s done for years on his own blog, Hutchins misrepresents the science on the subject of free-roaming cats. Here are just a few of the more glaring examples:

    1. That “KittyCam” study he refers to revealed just five birds killed—despite 1,000 hours of video monitoring 55 cats. As the PhD student conducting the research told CBS Atlanta in April: “Cats aren’t as bad as biologists thought” (Paluska, 2012).

    2. “TNR does not appear to be an effective method of controlling feral cat populations,” claims Hutchins. In fact, such successes have been documented (and countless others have been observed outside of formal research studies).

    Felicia Nutter, for example, reported that one of the sterilized colonies (which originally consisted of 10 cats) included in her PhD research “went extinct after 31 months of follow-up.” (Nutter, 2005) Three of 11 colonies monitored over an 11-year period on the University of Central Florida campus “were eventually depleted of cats,” though, admittedly, the accounting is hardly as straightforward as one might wish (Levy, Gale, & Gale, 2003).

    In December of 2009, the last of the Newburyport, Massachusetts’ “wharf cats” died. According to both Alley Cat Allies and the local paper, this colony once included something like 300 cats. A 1996 story in the Boston Herald describes “an estimated 200 wild, roaming cats” (Donlan, 1996). (Zorro, the last of the colony cats, was 16 years old.)

    3. Hutchins claims that “Toxoplasma gondii coming from freshwater run-off from cat litter in land-fills and feral cat colonies near our coasts has resulted in the death of thousands of marine mammals, including dolphins, whales, seals, sea lions, and sea otters.” Again, the scientific evidence suggests that the situation is far more complex than he would have us believe.

    As usual, Hutchins fails to acknowledge that the most common type of T. gondii found to be infecting sea otters is the Type X strain (Conrad et al., 2005), which has yet to be traced to domestic cats (Miller et al., 2008). And as one of the articles cited here notes, “dual infections of T. gondii and S. neurona [which is unrelated to cats] were more frequently associated with mortality and protozoal encephalitis than single infections, indicating a role for polyparasitism in disease severity” (Gibson et al., 2011).

    In other words, the link between domestic cats and marine mammal mortality is not nearly as direct as Hutchins claims.

    4. Hutchins claims that “the numbers of rabies cases in feral cats appear to be increasing.” Where’s the evidence? Rabies surveillance techniques simply do not allow for the kind of trend analysis implied by Hutchins’ comment.

    Like T. gondii, this is little more than scaremongering. Of the 49 rabies cases reported in humans since 1995, 10 were the result of dog bites that occurred outside of the U.S.; the remainder were traced either to wildlife or were of unknown origins (CDC, 2012a).

    Approximately 92 percent of rabid animals reported to the CDC during 2010 were wildlife. Cases among domestic animals included 303 cats (4.9 percent), 71 cattle (1.1 percent), and 69 dogs (1.1 percent) (Blanton, Palmer, Dyer, & Rupprecht, 2011). Since 1960, only two cases of human rabies have been attributed to cats (CDC, 2012b).

    5. According to Hutchins, “one study found that 42 percent of the items consumed by 8 coyotes living in Tucson, AZ, over a 5-month period were domestic cats.” In fact, this study found nothing of the kind.

    Between December 2005 and November 2006, researchers Shannon Grubbs and Paul Krausman (now president of The Wildlife Society) tracked eight radio-collared coyotes in Tucson, AZ, “observ[ing] 45 instances of coyotes consuming prey and fruit: 19 cats (42 percent), 15 unidentified rodent species (33.3 percent), 8 lagomorphs (17.8 percent), 1 bird (2.2 percent), and in 3 observations coyotes consumed dates (6.6 percent)” (Grubbs & Krausman, 2009).

    In order to know what percentage of a typical coyote’s diet is made up of domestic cats, the researchers would need to examine their stomach contents. They didn’t, because that wasn’t the purpose of their study.

    It’s ironic, in light of Hutchins’ ongoing campaign of misinformation, that he criticizes “local politicians who have little or no knowledge about the situation, are only told one side of the story, or are just taking the easy way out.” Indeed, Hutchins has, for years now, fueled any such ignorance.

    It’s disappointing to see National Geographic providing him the platform to continue doing so.

    Peter J. Wolf

    Literature Cited
    • Blanton, J. D., Palmer, D., Dyer, J., & Rupprecht, C. E. (2011). Rabies surveillance in the United States during 2010. Journal of the American Veterinary Medical Association, 239(6), 773–783.
    • CDC. (2012a). Human Rabies. Atlanta (GA): Centers for Disease Control and Prevention
    • CDC. (2012b). Recovery of a Patient from Clinical Rabies—California, 2011. Morbidity and Mortality Weekly Report, 61(4), 61–64.
    • Conrad, P. A., Miller, M. A., Kreuder, C., James, E. R., Mazet, J., Dabritz, H., et al. (2005). Transmission of Toxoplasma: Clues from the study of sea otters as sentinels of Toxoplasma gondii flow into the marine environment. International Journal for Parasitology, 35(11-12), 1155-1168.
    • Donlan, A. E. (1996, June 30). North Shore cat-lovers go… Where the wild things are. Boston Herald,
    • Gibson, A. K., Raverty, S., Lambourn, D. M., Huggins, J., Magargal, S. L., & Grigg, M. E. (2011). Polyparasitism Is Associated with Increased Disease Severity in Toxoplasma gondii-Infected Marine Sentinel Species. PLoS Neglected Tropical Diseases, 5(5), e1142.
    • Grubbs, S. E., & Krausman, P. R. (2009). Observations of Coyote-Cat Interactions. Journal of Wildlife Management, 73(5), 683–685.
    • Levy, J. K., Gale, D. W., & Gale, L. A. (2003). Evaluation of the effect of a long-term trap-neuter-return and adoption program on a free-roaming cat population. Journal of the American Veterinary Medical Association, 222(1), 42–46.
    • Miller, M. A., Miller, W. A., Conrad, P. A., James, E. R., Melli, A. C., Leutenegger, C. M., et al. (2008). Type X Toxoplasma gondii in a wild mussel and terrestrial carnivores from coastal California: New linkages between terrestrial mammals, runoff and toxoplasmosis of sea otters. International Journal for Parasitology, 38(11), 1319-1328.
    • Nutter, F. B. (2005). Evaluation of a Trap-Neuter-Return Management Program for Feral Cat Colonies: Population Dynamics, Home Ranges, and Potentially Zoonotic Diseases. North Carolina State University, Raleigh, NC.
    • Paluska, M. (2012). Kitty cameras show Athens cats on the prowl [Electronic Version], from

  9. Woodsman
    December 26, 2012, 12:27 am

    While it is true that overpopulation of humans is the #1 problem that we and all other species face today; this doesn’t excuse all the responsible, wise, and intelligent people from stopping all the ecological disasters caused by those phenomenally stupid and criminally negligent people that should have never been born in the first place.

    Cats are a man-made (through selective breeding) invasive species. And as such, cats being a product of man, are no less of a man-made environmental disaster than any oil-spill, radiation-fallout, chemical-spill, or other environmental disaster _caused_by_man_. Cats are not exempt from being removed from every natural environment, wherever and whenever they are found away from supervised confinement. Just as you would destroy Burmese Pythons and African Cichlids in every habitat where they exist in N. America. They started out as pets too. Many of our destructive invasive species pests started out as PETS discarded by criminally-irresponsible humans. Guess what happens to all those other non-native pets that became destructive invasive species? They are destroyed on-site by any means possible — no questions asked — none required.

    Cats are even worse than a multi-continent-sized oil-spill. They not only kill off rare marine-mammals along all coastlines (just as oil-spills do) from run-off from the land carrying cats’ Toxoplasma gondii parasites, they also destroy the complete food-chain in every ecosystem where cats are found. From smallest of prey that is gutted and skinned alive for cats’ tortured play-toys, up to the top predators — starved to death from cats destroying their ONLY foods. (Precisely what cats caused on my own lands not long ago.) They destroy everything that moves. They will even destroy native vegetation by destroying those animals that are pollinators or act as seed dispersers for those plants (as many rodent and bird species do) or those acting as plants’ pest-control. Cats can and will wipe out whole ecosystems — animal and plant.

    Cats need to disappear from all natural habitats PERMANENTLY. The sooner the better. They are breeding out of control at an exponential rate. The reason for “sooner the better” is that you can only hope you can halt the problem before it is beyond the reach of any method you eventually choose. Luckily, I caught the problem in time where I live (by humanely shooting and burying every last cat I saw, hundreds, collared or not, totally LEGAL). It seems nobody else is faring as well. Their time is being wasted by cat-lovers stopping them from doing the right thing. Asking or listening to any deranged invasive-species advocate for advice on how to clean up the ecological disaster that they created and perpetuate is about as useful as asking your local career thieves for advice and help to hide your valuables from their daily motives and activities. Ignore anything they might say and you too will solve the problem where you live.

    It worked 100% where I live!

  10. Woodsman
    December 26, 2012, 12:25 am

    Here’s how these ignorant, self-serving, and uneducated TNR-advocates are destroying your planet and all life on it.


    FACT: Trap & Kill failed because cats cannot be trapped faster than they exponentially breed out of control.

    FACT: Trap, Neuter, & Release (TNR) is an even bigger abject failure because these man-made ecological disasters cannot be trapped faster than they exponentially breed out of control, and they also continue the cruelly annihilate all native wildlife (from the smallest of prey up to the top predators that are starved to death), and the cats continue to spread many deadly diseases that they carry today — FOR WHICH THERE ARE NO VACCINES AGAINST THEM. Many of which are even listed as bioterrorism agents. (Such as Tularemia and The Plague — Yes, people have already died from cat-transmitted plague in the USA. No fleas nor rats even required. The cats themselves carry and transmit the plague all on their own.)

    FACT: THERE IS ABSOLUTELY _NOTHING_ HUMANE ABOUT TNR. Nearly every last TNR’ed cat dies an inhumane death by road-kill, from cat and animal attacks, environmental poisons, starvation, dehydration, freezing to death, infections, parasites, etc. And if very very lucky humanely shot to death or re-trapped and drowned (the two most common methods employed on all farms and ranches to protect their gestating livestock’s offspring and valuable native wildlife dying from cats’ Toxoplasmosis parasites). This doesn’t begin to count the thousands of defenseless native animals that cats skin alive and disembowel alive for their daily and hourly play-toys. The only difference in destroying cats immediately and humanely instead of trapping, sterilizing, then releasing them to an inhumane death; is that money isn’t going into an HSUS or SPCA board-member’s pocket, veterinarian’s pocket, cat-food company CEO’s pocket, or a drug-company CEO’s pocket. And that’s the ONLY difference!

    FACT: Cats are a man-made (through selective breeding) invasive species. And as such, are no less of a man-made environmental disaster than any other caused by man. Cats are even worse than an oil-spill of continent-sized proportions. They not only kill off rare and endangered marine-mammals along all coastlines from run-off carrying cats’ Toxoplasma gondii parasites, they destroy the complete food-chain in every ecosystem where cats are found. From smallest of prey gutted and skinned alive for cats’ tortured play-toys, up to the top predators that are starved to death from cats destroying their ONLY food sources. (Precisely what cats caused on my own land not long ago.)

    FACT: Hunted To Extinction (or in this case, extirpation of all outdoor cats) is the ONLY method that is faster than a species like cats can exponentially out-breed and out-adapt to. Especially a man-made invasive species like these cats that can breed 2-4X’s faster than any naturally occurring cat-species.

    FACT: In _TWELVE_YEARS_ Alley Cat ALL-LIES of NYC have only reduced feral cats in their own city by 0.08% to 0.024% (as the months go on that percentage becomes more insignificant), allowing more than 99.92% to 99.976% to exponentially breed out of control. Here’s how Alley-Cat-ALL-LIES’ deceptive math works: If you TNR 4 cats and 3 get flattened by cars this translates to 75% fewer feral-cats everywhere. Alley Cat ALL-LIES can’t even reduce cats in their own city, yet they promote it as a worldwide solution. Then even bigger fools fall for it and promote it.

    FACT: When researching over 100 of the most “successful” TNR programs worldwide, JUST ONE trapped more than 0.4%. Oregon’s 50,000 TNR’ed cats (the highest rate I found) is 4.9% of all ferals in their state. Yet, by applying population growth calculus on the unsterilized 95.1% they will have trapped only 0.35% of all cats in their state sometime this year. Less than 0.4% is a far cry from the required 80%-90% to be the least bit effective.

    FACT: Their mythical “vacuum effect” is a 100% LIE. A study done by the Texas A&M University proved that any perceived “vacuum” is just the simple case that CATS ATTRACT CATS. Get rid of them all and there’s no cats there to attract more. I proved this myself by shooting and burying hundreds of them on my own land. ZERO cats replaced them FOR 3 YEARS NOW. If you want more cats, keep even one of them around, more will find you. That university study also found that sterilized cats very poorly defend any territory. Non-sterilized cats, being more aggressive, take over the sterilized cats’ resources (shelter & food if any). If there is any kind of “vacuum effect” at all, it is that sterilizing cats cause non-sterilized cats to restore the reproductive void.

    FACT: During all this investigation I have discovered something that is unfaltering without fail. Something that you can bet your very life on and win every last time. That being — IF A TNR CAT-HOARDER IS TALKING THEN THEY ARE LYING. 100% guaranteed!

  11. Woodsman
    December 26, 2012, 12:24 am

    What a total load of BS. There *IS* an easy answer!

    Licensing and laws do nothing to curb the problem. If cats are required to be licensed then cat-lovers just stop putting collars on their cats, as they did by me. And they won’t even bother getting them micro-chipped, especially not that They want absolutely nothing that can hold them legally responsible, liable, and accountable for the actions of their cats. It’s why many of them even keep cats in the first place. We’re not talking about the topmost responsible citizens of the world, you know. They don’t want that responsibility of what their cat has done coming back on them. If they had even one iota of a sense of responsibility and respect for all other lives on this planet we wouldn’t even be having these discussions.

    On the other hand, I found something that DOES work, and works well, and works fast (well, relative to the years it takes trying to reason with deceitful and lying cat-lovers that accomplishes ABSOLUTELY NOTHING). Where I live cat-lovers have learned that _ALL_ cats, stray and feral, collared or not, ear-tipped or not (because TNR con-artist liars now just clip cats’ ears only, WITHOUT sterilizing or vaccinating them, to protect their hoarded cats from being trapped and euthanized), _ALL_ their cats are humanely shot on sight and buried whenever found away from supervised confinement.

    The ONLY thing that works is destroying any of their cats found outdoors off their property. They either learn to stop getting more cats that die under the wheels of cars or from animal attacks, or they finally learn how to be a responsible pet owner, respectful neighbor, and learn to keep their invasive species animal under confined supervision, as it should be. Win win win all around. You can either destroy their cat for them humanely, or let their lack of concern for their cat cause it to die inhumanely. By destroying their cat for them humanely you are showing them that you care more about their cat than even they do. A bullet is by far the most humane death that any free-roaming cat will ever meet. Anything else is all inhumanely downhill from there. Their only other options are being hit by cars, environmental poisons, cat & animal attacks, disease and parasites, freezing, etc., etc.

    You can’t train a cat to stay home but I found that, in time, you CAN train a cat-owner into being a responsible pet-owner and a respectable neighbor. Most of them are so phenomenally stupid, disrespectful, and criminally irresponsible though that you have to make at least 12-15 of their cats permanently disappear before they even start to figure out what they’ve been doing wrong all during their sorry, useless, and pathetic lives.

    If you live in an area where its not legal to use firearms to destroy any animal that is threatening the health and safety of you, your family, your animals, or property (as it *IS* legal in most every area of the nation — shoot to maim is animal cruelty but shoot to kill is a perfectly legal way to humanely destroy any nuisance animal on your own property); then check into laws regarding air-rifles with ballistics speeds of 700-1200 fps and using pointed vermin-pellets in no-firearms zones. Many of the newer ones even come with their own sound-suppressor designs built-in, being specifically designed for shooting vermin cats in urban areas, the demand is that great. Failing that, then there’s always the SSS and TDSS Cat Management Programs that are exploding in popularity worldwide. Shoot, Shovel, & Shut-Up; or Trap, Drown, Shovel, & Shut-Up. Both methods are legal on every square foot of this earth. No local laws were violated if it never happened! (Where cats have already learned to evade all trapping methods, then inexpensive generic 1-adult-strength acetaminophen (overseas a.k.a. paracetamol) pain-relievers are a more species specific vermin poison. But you really need to retrieve and dispose of that carcass safely so that native wildlife won’t die from the many diseases cats spread even after their death.)

    Good luck!