Operation Sisyphus

The draft environmental assessment (EA) for the Florida Keys National Wildlife Refuges Complex Integrated Predator Management Plan (download PDF), released last week by the U.S. Fish and Wildlife Service (FWS), aims to eliminate free-roaming cats in the Keys. Not that this is anything new—FWS (along with USDA, and some state agencies) has been trying to do this for years now.

Plans include the trapping/removal of free-roaming cats—owned and unowned alike—from refuge lands and other public lands nearby, as well as from other land (including private property) where cats may be considered a threat to vulnerable native species. TNR has been dismissed as an option, and FWS proposes to prohibit the feeding of feral cats wherever possible.

Unfortunately, the proposed plan is unlikely to be any more successful than previous efforts. There’s plenty to dislike about the FWS plan—including the risk that it may set a dangerous precedent nationwide. The deadline for public comments (see Plan for details) is February 3.

Justification or Rationalization?
In a section of the document called Justification for Management Action, FWS lays out their numerous grievances against “non-native species and human-subsidized populations of native predators.” [1] As a review of the relevant literature, the sub-section on domestic cats leaves much to be desired is a train wreck.

In fact, if this were a college-level term paper, it would likely receive a failing grade—followed, perhaps, by disciplinary action. (And, if it were allowed under the law, maybe a drug test, too.)

Among the references cited here (about three-quarters of which I’m familiar; the rest I’m still chasing down) is, admittedly, some rather damning evidence. For example:

  • The near-extirpation of rock iguanas from Pine Cay in the Caicos Islands during the 1970s. “The decline, from an estimated adult lizard population of nearly 5,500, was due primarily to predation by domestic dogs and cats introduced to the island simultaneously with hotel construction.” [2] (Strangely, FWS cites Iverson’s paper not as an example of a near-miss, but of a global extinction. This, however, pales in comparison to the “strangeness” of many of their other citations.)
  • On Little Barrier Island, off the coast of New Zealand, cats “were considered to have been the sole cause of the local eradication of North Island saddleback and to have contributed to the extinction of the Little Barrier snipe, and to threaten, by their continued presence, grey-faced, black, and Cook’s petrels. Cats probably also contributed to the decline of tuatara and the 12 lizard species known to be present on Little Barrier Island.” [3]

On the other hand, much of the FWS’s evidence is, at best, circumstantial. Among the studies cited to support their claim that “free-roaming cats have been shown to be a major cause of 33 native species extinction [sic] globally,” is a 1987 paper by Cruz and Cruz, in which the authors, studying Galápagos Petrels, found that cats were hardly the only culprits:

“They are threatened by introduced rats, which attack eggs and young chicks… dogs and pigs which prey on eggs, nestlings and adults. Introduced goats, burros and cattle destroy nesting habitat and trample nests. A different combination of these pests and predators exists at each of the petrel nesting sites, while three of the islands are plagued by all of them.” [4]

And, as with the rock iguanas, the FWS would have the public believe the Galápagos Petrel is among those 33 extinctions. In fact, the birds are still there, though they are listed as Critically Endangered.

The story is similar for the 1986 paper by Kirkpatrick and Rauzon, another purported link between free-roaming cats and species extinctions. Kirkpatrick and Rauzon found that more than 90 percent of the diet of free-roaming cats on Jarvis Island and Howland Island was made up of Sooty Terns, Wedge-tailed Shearwaters, and Brown Noddies—each of which is listed as a species of Least Concern.

Another of the papers cited by FWS has nothing to do with extinctions at all. As the authors themselves describe it, their study was an evaluation of “whether a collar-worn pounce protector, the CatBib, reduces the number of vertebrates caught by pet cats and whether its effectiveness was influenced by colour or adding a bell.” [5]

FWS argues that “many of the species impacted by free-roaming cats are federally listed threatened or endangered species and federally protected migratory birds.” While probably true, this statement is also largely meaningless. According to the 2009 State of the Birds report, published by the Department of the Interior (which oversees FWS):

“The United States is home to a tremendous diversity of native birds, with more than 800 species inhabiting terrestrial, coastal, and ocean habitats, including Hawaii. Among these species, 67 are federally listed as endangered or threatened. An additional 184 are species of conservation concern because of their small distribution, high threats, or declining populations.” [6]

That translates to approximately 31 percent of all birds in this country being species of concern. FWS makes it sounds as if perhaps the cats are targeting these birds; in fact, they could just as easily have claimed that many of the species impacted by all forms of mortality are federally listed threatened or endangered species and federally protected migratory birds of these birds.

Hang in there, though—it gets better. I mean worse.

Also listed among the evidence of island extinctions were Coleman and Temple’s 1993 survey of rural Wisconsin residents about their outdoor cats [7], and Churcher and Lawton’s “English Village” study [8]. (While England is an island, it’s quite a stretch to suggest that Felmersham’s House sparrows are at risk of extinction.)

When it comes to the disruption caused by cats to “the abundance, diversity, and integrity of native ecosystems,” FWS turns to, among others, studies by Hawkins [9] and Jessup. [10]

As I’ve discussed previously, Hawkins’ dissertation work was plagued with problems that raise serious doubts about his rather triumphant conclusions—“the preference of ground feeding birds for the no-cat treatment was striking,” [9] for example. A closer look reveals that five of the nine ground-feeding birds showed no preference for either area of the study site. One could, based on Hawkins’ findings, just as easily conclude that more than half of the ground-feeding species studied were indifferent to the presence of cats.

Jessup cites some well-known predation studies, but his concern is the condemnation of “trap, neuter, and reabandon,” [10] as he calls it (“Abandonment of animals cannot be morally justified and is illegal under state humane laws… If it is illegal to abandon a cat once, how can it be legal to do it a second time? How can veterinarians justify being party to abandonment, an illegal act of animal cruelty?” [10])

FWS suggests that “free-roaming cats kill at least one billion birds every year in the U.S., representing one of the largest single sources of human-influenced mortality for small native wildlife,” [1] supporting their assertion with just three sources, one of which is Rich Stallcup’s 1991 article from the Observer, a publication of the Point Reyes Bird Observatory. But “A Reversible Catastrophe” is very light on science—and Stallcup gets most of that wrong. Mostly, the article is Stallcup’s manifesto regarding neighborhood cats:

“If you have a garden, why not proclaim it a wildlife sanctuary and protect it from non-native predators? If roaming cats come into your sanctuary to poach the wildlife under your stewardship, you have the right and perhaps even the duty to discourage them in a serious way.” [11]

Discourage them? Among Stallcup’s suggestions: “…try a B-B or pellet gun. There is no need to kill or shoot toward the head, but a good sting on the rump seems memorable for most felines, and they seldom return for a third experience.” [11]

No feral cat witch hunt would be complete without some public health threat fear-mongering, and FWS’s plan is no different:

“According to the Centers for Disease Control (CDC), free-roaming cats not only threaten wildlife through direct predation but also serve as vectors for a number of diseases including rabies, cat scratch fever, hookworms, roundworms and toxoplasmosis. Some of these diseases can be transmitted to other domestic animals, native wildlife, and in some cases, humans.” [1]

But the CDC site makes no mention of cats being a threat to wildlife. And humans? “Although cats can carry diseases and pass them to people, you are not likely to get sick from touching or owning a cat.” And, notes the CDC, “People are probably more likely to get toxoplasmosis from gardening or eating raw meat than from having a pet cat.”

There’s even a link to another page on the CDC’s site, called “Health Benefits of Pets.”

And finally, there’s the paper by Sax and Gaines. If the previous examples miss their mark, this one’s a full-blown non-sequitur. Though the authors do mention “the extinction of many native animal species on islands” [12] briefly in their introduction, the purpose of the paper is, as the authors state plainly enough, to “show that the number of naturalized plant species has increased linearly over time on many individual islands.” [12, emphasis mine]

•     •     •

FWS intends to eliminate free-roaming cats from the Florida Keys, and this is the best they can do? If so, well, perhaps they ought to be doing something else. If this is their “justification for action,” then any subsequent action can, I think, rightfully be considered unjustified.

Predator Management
Among the animals to be monitored throughout and/or removed from the four refuges that make up the Florida Keys National Wildlife Refuges Complex (National Key Deer Refuge, Key West National Wildlife Refuge, Great White Heron National Wildlife Refuge, and Crocodile Lake National Wildlife Refuge) are non-native reptiles and rodents, native raccoons, and, of course, the cats.

“Presence of exotic non-native iguanas, lizards, and large-bodied snakes will be detected through reports, incidental sightings, and the community-based interagency ‘Python Patrol’ network. Exotic reptiles will be immediately dispatched in accordance with AVMA guidelines for humane euthanasia.” [1]

“Any non-native opossum, armadillo, or rat caught incidentally in the live traps targeted for cats on Refuge lands will be immediately dispatched in accordance with the American Veterinary Medical Association (AVMA) guidelines for humane euthanasia. All native species will be immediately set free.” [1, emphasis mine]

“Raccoons trapped incidentally in live traps targeted for cats or other non-native predators will be released alive at the trap location… Raccoons that exhibit severe disease or other serious health issues will receive appropriate evaluation, which may include care by a state-certified wildlife rehabilitator or euthanasia as recommended by a qualified veterinarian or animal control services provider… If field studies and monitoring indicate that raccoon populations are having a negative impact on endangered species, the USFWS will reevaluate the need to implement more direct control by removal of raccoons from sensitive habitats. Removal could include, but not be limited to, transfer to a wildlife park or zoo, a state-certified wildlife rehabilitator, or euthanasia. Any decision by the Service to use lethal control measures on raccoons will trigger additional public notification and an amendment to this EA.” [1]

Free-roaming Cats
But, as I say, the cats are the real focus here: “The USFWS will remove all free-roaming cats found on Refuge lands through live trapping,” at which point, the cats will become of the responsibility of any one of three (currently, two; a third contractor is currently being sought) Monroe County animal control providers.

“The Monroe County animal control service provider will have the authority to determine the final disposition of the trapped cats according to county ordinances and standards, which may include returning to owner, adopting out, relocating to a long-term cat care facility on the mainland, or euthanizing.” [1]

Of course, it’s no secret what happens to the vast majority of feral cats brought into shelters. As Nathan Winograd writes in his book Redemption: The Myth of Pet Overpopulation and the No Kill Revolution in America, “there is no other animal entering a shelter whose prospects are so grim and outcome so certain.”

I asked Connie Christian, Executive Director of the Florida Keys SPCA, about this last week. “Every cat brought to our facility is assessed to determine their disposition,” Christian told me via e-mail. “Every attempt is made to return ‘non-feral’ cats to their owners or place for adoption.”

“Unfortunately,” she continued, “we do not have an outlet for feral cats that are brought to us without a request for return.” Which would likely be the case for cats unlucky enough to be trapped by FWS. (Interestingly, FKSPCA is involved with TNR, which FWS wants to eliminate—more on that in a moment.)

What about that “relocation to long-term facilities on the mainland” option? There was some discussion of this option during stakeholder meetings that took place in 2008. And local papers carried stories suggesting the possibility. [13, 14] Now it looks like FWS is dumping this is the laps of Monroe County animal control providers.

I guess they can say they tried.

Expanding Territory
But FWS isn’t stopping at their property line—and the four refuges included in the plan already make up, according to my calculations, more than 28 percent of the Keys’ total land mass. According to the South Florida Multi-Species Recovery Plan (MSRP), FWS has plans to use land acquisition and conservation easements or agreements to protect the endangered Lower Keys marsh rabbit. [15]

The MSRP, excerpts of which are included in the EA, also spells out FWS’s intention to “remove nuisance feral cats” from land “near rabbit habitat” in the Lower Keys. [1] Additional plans include deed restrictions “to prohibit free-roaming cats” [1] in areas where they might be a threat to the rabbits, the Key Largo Woodrat, or the Key Largo Cotton Mouse. And to “enforce deed restrictions of cat control in Ocean Reef Club and other areas.” [1]

The Ocean Reef Club, of course, is home to ORCAT, perhaps the best known—and certainly one of the most successful—TNR programs in the country. According to their website, ORCAT has reduced the island’s population of cats from approximately 2,000 cats, in the early 1990s, to about 350 today, “about 100 of which reside at the Grayvik Animal Care Center.”

Frankly, I’m not sure what FWS means by “enforce deed restrictions” (one of many follow-up items on my to-do list). Other aspects of their plan, however, are straightforward:

“Feral cat colonies and feeding stations on Refuge lands will be identified and removed. The USFWS will also coordinate with county and state agencies to assist in the identification and removal, where feasible and legal, cat colonies and feeding stations on other public properties that are adjacent to or near Refuge lands. Extensive public outreach will be conducted to encourage people who feed free-roaming cats to cease doing so, and to promote trapping and relocating those animals to long-term facilities on the mainland where they will no longer be a threat to Refuge’s wildlife.” [1]

Something else that’s clear: FWS is going after pet cats, too. The MSRP includes plans to “establish a program to license domestic cats, implement leash laws, eliminate cat-feeding stations, implement spay and neuter program, increase awareness through educational material, test diseases, and remove nuisance feral cats.” [15]

Is this mandatory spay/neuter (which has been shown to fail when implemented in the absence of adequate low- and no-cost services)? Does the FWS plan to test pets for, say FIV and FeLV? Lots of unanswered questions here, obviously.

It’s no surprise, then, given their plan for the removal of feeding stations—and cats—that FWS is staunchly opposed to TNR, which, they argue “does little to reduce cat predation on native wildlife.” [1]

Success Stories
“In addition,” argues FWS, “the TNR method has little valid scientific support for claims that it actually reduces cat colony numbers over time and often has been shown to attract people to release new cats into an area.” [1]

Ironically, some of the greatest TNR success stories are right there in the papers cited by FWS. Natoli, for example, reported a 16–32 percent decrease in population size over a 10-year period across 103 colonies in Rome—despite a 21 percent rate of “cat immigration.” [16]

Castillo and Clarke, though highly critical of TNR documented remarkably little predation in the two Florida parks they used for their study. In fact, over the course of approximately 300 hours of observation (this, in addition to “several months identifying, describing, and photographing each of the cats living in the colonies” [17] prior to beginning their research), Castillo and Clarke “saw cats kill a juvenile common yellowthroat and a blue jay.” [17]

“Cats also caught and ate green anoles, bark anoles, and brown anoles. In addition, we found the carcasses of a gray catbird and a juvenile opossum in the feeding area.” [17]

Any TNR program contends with the unfortunate (and illegal) dumping of cats. Still, it’s difficult to imagine that the presence or absence of a nearby TNR program would affect a person’s decision to abandon his/her pet cat(s). (If any studies had demonstrated such a connection, TNR opponents would surely cite them!) On the other hand, cats dumped near a managed colony are far more likely to be adopted and/or sterilized—thereby mitigating their potential impact on the overall population of unowned cats—as well any impacts to wildlife and the environment.

Moreover, FWS ignores the value of population stabilization. Julie Levy, Maddie’s Professor of Shelter Medicine in the University of Florida’s College of Veterinary Medicine, and one of the country’s foremost experts on feral cats, argues that “wildlife benefits when populations of cats that are trending rapidly upwards are at least stabilized” [18].

Among the more perplexing aspects of FWS’s argument is their claim that “TNR practices are prohibited on National Wildlife Refuges, and violate the Endangered Species Act (ESA) and the Migratory Bird Treaty Act (MBTA) because they may result in the direct harm of protected species.” [1]

This is an argument that’s been thrown around since at least 2003, when Pamela Jo Hatley, then a law student, suggested the possibility. But that’s all it was—and, apparently, is—a possibility.

“It is quite obvious that cats can be lethal to birds,” writes Hatley, “and if the death of a migratory bird can be traced to a cat, or a cat colony, which can be further traced to an individual or organization, there may be strict liability for that person under the MBTA.” [19] Hatley’s argument for violations of the Endangered Species Act is similarly speculative: “…persons who release cats into the wild or who maintain feral cat colonies could be found liable for a take under section 9 of the ESA if maintenance of feral cats in the wild is found to kill or injure wildlife by degrading habitat.” [19]

It’s been nearly eight years now—a period during which TNR has undoubtedly increased substantially across the country—so where are all the court cases? If this were as black-and-white as FWS makes it sound, there wouldn’t even be a discussion about TNR (and the Urban Wildlands Group would likely have taken a very different tack in Los Angeles).

Finally—perhaps in a desperate attempt to appear as though their plan has the support of animal welfare organizations—FWS gives PETA a plug.

“Some animal advocates therefore often agree that traditional TNR programs are not the most appropriate choice, especially where cats are released near designated wildlife areas and at-risk wildlife populations (see the People for the Ethical Treatment of Animals’ Animal Rights Uncompromised fact sheets at www.peta.org/about/why-peta/default.aspx). For these reasons, TNR was considered but dismissed from further evaluation.” [1]

PETA, of course, is also opposed to caged birds, crating dogs, and zoos. When PETA is the only “animal advocate” you can get to endorse your approach, it’s time to rethink it.

Operation Sisyphus
The purpose of FWS’s Plan/EA “is to conserve and restore federally-listed species and protect all native fauna and flora on the [refuges] from population decline and potential extirpation or extinction due to predation by non-native species and human-subsidized populations of native predators.” [1]

Will the plan work? Only time will tell, of course—but there’s plenty of reason for skepticism. If their “literature review” is any indication, FWS either doesn’t have a particularly strong grasp of the issues involved—or they’re not interested in sharing that understanding with the public.

Nitpicking? I don’t think so. In their attempt to focus—however carelessly—on the impacts of cats, FWS overlooks some key factors.

Mesopredator Release
FWS refers to two often-cited papers [20, 21] as evidence of cats disrupting native ecosystems, but fails to acknowledge the larger point made by the authors: the mesopredator release phenomenon. “In the absence of large, dominant predators,” write Soulé et al., “smaller omnivores and predators undergo population explosions, sometimes becoming four to 10 times more abundant than normal.” [20]

In Soulé’s example, coyotes were the dominant predators, while cats were the mesopredators. In other contexts, however, cats have been shown to play the dominant predator role with rats becoming the mesopredators.

Mathematical modeling of the mesopredator release phenomenon illustrates the complexities involved in eradication efforts, even on small islands. As Courchamp et al. explain, “although counter-intuitive, eradication of introduced superpredators, such as feral domestic cats, is not always the best solution to protect endemic prey when introduced mesopredators, such as rats, are also present.” [22] Fan et al. warn of the risks involved with such eradication efforts: “In some cases, it may cause a disastrous impact to managed or natural ecosystems.” [23]

Macquarie Island, located roughly halfway between New Zealand and Antarctica, offers a well-documented example of such a disastrous impact. In 2000, cats were eradicated from this United Nations Educational, Scientific and Cultural Organization World Heritage Site in order to protect its seabird populations. The resulting rebound in rabbit and rodent numbers, however, has had its own disastrous impact. “In response, Federal and State governments in Australia have committed AU$24 million for an integrated rabbit, rat and mouse eradication programme.” [24]

Could something like this happen in the Florida Keys?

According to FWS, non-native rats are already “prevalent in residential and commercial areas.” [1] Should the removal of cats create a spike in their numbers, FWS suggests that they’re prepared to remove the rats, too: “Noticeable population increases based on reports, road kill, or other specific or auxiliary data may initiate targeted control and eradication efforts in addition to incidental capture…” [1]

But controlling these rats is complicated considerably by the need to protect Lower Keys marsh rabbits. The MSRP warns of these rabbits coming into contact with pesticides and “poisons used to control black rats.” [15]

“In a 1993 Biological Opinion, the FWS investigated the effects of vertebrate control agents on endangered and threatened species and determined that several chemicals (e.g., Pival) would jeopardize the continued existence of the Lower Keys marsh rabbit. Chemicals—such as Pival—a rodenticide used to kill rats, are lethal if ingested. The FWS also concluded that if development in the Keys continues to increase, the potential for these animals to come in contact with such chemicals also increases, as does the potential for their extinction. Based on these findings, the FWS believes the continued use of such chemicals will result in the deaths of Lower Keys marsh rabbits. Given that the majority of occupied habitat is adjacent to urbanized areas, and that urbanization continues to expand into their habitat, then it can reasonably be predicted that the use of such chemicals has had a negative impact upon the Lower Keys marsh rabbit that may prevent its recovery.” [15]

Removing Cats
It’s also not clear that FWS will be able to remove the free-roaming cats from the Keys. For one thing, they have no idea how many are there. Only now—after years of struggling with this issue—does FWS propose to “implement monitoring and conduct further research as needed to determine abundance and distribution of free-roaming cats throughout the Refuge, document effectiveness of management actions taken or not taken on cat populations, and determine the impacts on the ecosystems and native species to aid in the adaptive management process.” [1]

Plus, FWS has a rather poor track record when it comes to actually trapping cats.

In 2007, they “received $50,000 to remove cats from federal refuges on Big Pine Key and Key Largo, and to protect endangered marsh rabbits, silver rice rats and other animals and birds that call the refuges home.” [25] Reports (from what I can tell, nothing official has been issued) suggest that fewer than 20 cats were caught—some of which were returned to their owners (kudos to FWS and USDA)—along with 81 raccoons, 53 of which were released alive. [26]

I think it’s safe to say that the Keys’ wildlife reaped little or no benefit from this effort. Had that same money been used for TNR, on the other hand…

So what’s different this time around?

Déjà Vu
All the while I’ve been doing the research for this post, I’ve been haunted by two quotes I’ve used rather extensively in the past. Actually, the first is not a quote as such, but the title of Merritt Clifton’s excellent article: Where cats belong—and where they don’t. [27]

The second comes from Gary Patronek, who argues that “the release of cats into an environment where they would impact endangered or threatened species, or even into wildlife preserves or refuges, is inexcusable.” [28] Patronek, the former Director of the Center for Animals and Public Policy at the Cummings School, and one of the founders of the Hoarding of Animals Research Consortium, continues:

I do not believe that this is being advocated by cat protectors who see urban, managed colonies as an imperfect but still preferable alternative to the euthanasia of healthy animals. Abandoned pet cats whose own habitat has been reduced to colonies, and the wild species endangered by clear-cutting or beachfront development, are casualties of the same callous disregard for the lives of animals. I see little justification for shifting the role of cats to that of scapegoat.” [28, emphasis mine]

Well, isn’t this precisely what I’m advocating? I honestly don’t know.

Here’s what I do know:

There is no doubt that the Florida Keys are immensely valuable for their diversity of animal and plant life, some of which can be found nowhere else in the world. Due to a wide range of factors (most of them human-caused), this habitat has become quite fragile, with some animal and plant species on the brink of extinction. And, in such habitats, it’s been shown that free-roaming cats can have a significant negative impact.

I also know that where cats have been eradicated, the process is a horror. In fact, it’s spelled out in some of the papers cited by FWS (though, understandably, they don’t draw attention to that):

  • Nogales et al., describing the “success” of Marion Island, note, “it took about 15 years of intense effort to eradicate the cats, combining several methods such as trapping, hunting, poisoning, and disease introduction… The use of disease agents or targeted poisoning campaigns hold promise for an initial population reduction in eradication programs on large islands—such an approach may save effort, time, and money.” [29]
  • Cruz and Cruz point out that, of all the non-native mammals there, cats were “the most difficult to control or eliminate on Floreana Island.” Although “hunting with dogs was the single most effective method employed and it gave a sure body count,” the authors warn that “the method was costly and with the limited manpower available was only useful over small areas. Both poisoning and trapping were effective and the combination of the three methods is probably the most effective approach, as well as being the best use of time and materials.” [4]
  • Veitch describes efforts on 11-square-mile Little Barrier Island as “a determined [cat] eradication attempt” involving “cage traps, leg-hold traps, dogs and 1080 poison were used, but leg-hold traps and 1080 poison were the only effective methods.” [3] Four cats were also infected with Feline enteritis, but “because of the poor reaction to the virus no other cats were dosed and none were released… Altogether, 151 cats were known to have been killed before the eradication was declared complete. Important lessons learnt can be transferred to other feral cat eradication programmes.” [3] (By way of comparison, the Keys are approximately 137 square miles in total area.)

I know that ecosystems—especially those as fragile as the Keys—are incomprehensibly complex, and that tinkering with them is incredibly risky. And there’s plenty we simply do not know, and cannot—despite our best efforts—predict.

But I know, too, that time is short. And that we’ll never have all the answers we’d like to have before the need for action precludes further inquiry.

Put another way: I’ve given this issue a lot of thought—and, here’s what I’m afraid will happen in the Keys:

FWS will proceed with their plan, rounding up cats—ferals and pets alike—on and “near” public lands. The pet cats will mostly be returned, but some mistakes—the risk of which will likely increase in an atmosphere of mass trapping—will surely be made. Feral cats will be killed.

Progress will move slowly, as these things often do—far too slowly to keep up with reproduction rates. If feeding and TNR are eliminated (to whatever extent possible) throughout the Keys, the cats will simply “go underground.” No more monitoring—and sterilizing—by the “foot soldiers” who currently care for colonies of cats.

Indeed, it’s quite likely that feral cat complaint calls to Monroe County, FWS, and the USDA would taper off considerably, as it becomes clear that such a call is essentially a death sentence. Thus, the cats become that much more difficult to locate—and sterilize. The population, therefore, increases.

Using a population model, Andersen, Martin, and Roemer have suggested that, in the absence of a sterilization program, 50 percent of cats would have to be removed in order for a colony to decrease 10 percent annually. [30] By contrast, the authors suggest that 75 percent of cats would need to be sterilized to achieve the same result.

This model has its flaws, as I’ve explained elsewhere, but the study is one many researchers are familiar with. And, frankly, it’s convenient for my purposes here.

Even if Andersen et al. are off by a factor of two, FWS would need to “remove” 25 percent of the free-roaming, unsterilized (and once they chase away the colony caretakers, it won’t be long before that’s the norm) cats continuously in order to achieve a 10 percent reduction in overall numbers.

Does anybody really think that’s going to happen? Where’s the evidence to suggest that it’s even possible?

FWS has—it seems—taken off the table the unspeakable methods so often employed on small, uninhabited islands.

“While lethal control is allowed by Refuge System policy, it is not a socially acceptable approach and is inconsistent with the points of consensus developed by the stakeholder group. This alternative would likely not be logistically feasible on a FKNWRC-wide basis and would not allow for adaptive management under a strategic habitat conservation approach.” [1]

But they’ve also taken TNR off the table. So, what’s left? We’re back to doing what we’ve been doing for years now—which, of course, is how we got into this mess in the first place.

From what I can tell, the FWS plan is nothing more than a warmed-over version of old-school trap-and-remove, an approach Mark Kumpf, president of the National Animal Control Association President from 2007 to 2008, describes as “bailing the ocean with a thimble.” [31] (There’s a metaphor that ought to resonate with people in the Keys!)

If so, it’s easy to imagine the losers in the deal—the cats, obviously, but also all of the wildlife FWS wants to protect. And the taxpayers, too, of course—not much of a return on investment for all of us, no matter what our position might be on feral cats, wildlife conservation, and the like.

The question is, where are the winners?

Literature Cited
1. n.a., Draft Environmental Assessment: Florida Keys National Wildlife Refuges Complex Integrated Predator Management Plan. 2011, U.S. Fish & Wildlife Service: Big Pine Key, FL.

2. Iverson, J.B., “The impact of feral cats and dogs on populations of the West Indian rock iguana, Cyclura carinata.” Biological Conservation. 1978. 14(1): p. 63–73. http://www.sciencedirect.com/science/article/B6V5X-48XKN72-1NN/2/bff9bfdeecb8ff6cec68527221b99a97

3. Veitch, C.R., “The eradication of feral cats (Felis catus) from Little Barrier Island, New Zealand.” New Zealand Journal of Zoology. 2001. 28: p. 1–12. http://www.royalsociety.org.nz/publications/journals/nzjz/2001/001/

4. Cruz, J.B. and Cruz, F., “Conservation of the dark-rumped petrel Pterodroma phaeopygia in the Galápagos Islands, Ecuador.” Biological Conservation. 1987. 42(4): p. 303–311. http://www.sciencedirect.com/science/article/B6V5X-48XKMBP-17J/2/f81b57e317f217802d9aca8b6927a88c

5. Calver, M., et al., “Reducing the rate of predation on wildlife by pet cats: The efficacy and practicability of collar-mounted pounce protectors.” Biological Conservation. 2007. 137(3): p. 341-348. http://www.sciencedirect.com/science/article/B6V5X-4NGBB7H-3/2/456180347a2c3916d1ae99e220dd329e

6. n.a., State of the Birds, United States of America, 2009. 2009, U.S. Department of Interior: Washington, DC. p. 36.

7. Coleman, J.S. and Temple, S.A., “Rural Residents’ Free-Ranging Domestic Cats: A Survey.” Wildlife Society Bulletin. 1993. 21(4): p. 381–390.

8. Churcher, P.B. and Lawton, J.H., “Predation by domestic cats in an English village.” Journal of Zoology. 1987. 212(3): p. 439-455. http://dx.doi.org/10.1111/j.1469-7998.1987.tb02915.x

9. Hawkins, C.C., Impact of a subsidized exotic predator on native biota: Effect of house cats (Felis catus) on California birds and rodents. 1998, Texas A&M University.

10. Jessup, D.A., “The welfare of feral cats and wildlife.” Journal of the American Veterinary Medical Association. 2004. 225(9): p. 1377-1383. http://www.avma.org/avmacollections/feral_cats/javma_225_9_1377.pdf

11. Stallcup, R., “A reversible catastrophe.” Observer 91. 1991(Spring/Summer): p. 8–9.

12. Sax, D.F. and Gaines, S.D., Species invasions and extinction: The future of native biodiversity on islands, in In the Light of Evolution II: Biodiversity and Extinction,. 2008: Irvine, CA. p. 11490–11497. www.pnas.org/content/105/suppl.1/11490.full

13. n.a. (2007, March 29). Key Deer Refuge wants to control feral cats: A plan to round up feral cats in the National Key Deer Refuge on Big Pine and No Name keys has animal-rights groups and area cat owners upset. The Reporter.

14. Busweiler, R. (2008, December 1). Feds begin drafting rabbit protection plan—BIG PINE KEY. The Key West Citizen.

15.  n.a., Multi-Species Recovery Plan for South Florida: Lower Keys Rabbit. 1999, U.S. Fish and Wildlife Service: Atlanta, GA. p. 151–171. www.fws.gov/verobeach/images/pdflibrary/lkmr.pdf

16. Natoli, E., et al., “Management of feral domestic cats in the urban environment of Rome (Italy).” Preventive Veterinary Medicine. 2006. 77(3-4): p. 180-185. www.kiccc.org.au/pics/FeralCatsRome2006.pdf

17. Castillo, D. and Clarke, A.L., “Trap/Neuter/Release Methods Ineffective in Controlling Domestic Cat “Colonies” on Public Lands.” Natural Areas Journal. 2003. 23: p. 247–253.

18. Levy, J.K., Personal communication, 2010.

19. Hatley, P.J., Feral Cat Colonies in Florida: The Fur and the Feathers Are Flying. 2003, University of Florida Conservation Clinic: Gainsville, FL. www.law.ufl.edu/conservation/pdf/feralcat.pdf

20. Soulé, M.E., et al., “Reconstructed Dynamics of Rapid Extinctions of Chaparral-Requiring Birds in Urban Habitat Islands.” Conservation Biology. 1988. 2(1): p. 75-92. http://deepblue.lib.umich.edu/bitstream/2027.42/74761/1/j.1523-1739.1988.tb00337.x.pdf

21. Crooks, K.R. and Soulé, M.E., “Mesopredator release and avifaunal extinctions in a fragmented system.” Nature. 1999. 400(6744): p. 563–566. http://www.nature.com/nature/journal/v400/n6744/abs/400563a0.html

22. Courchamp, F., Langlais, M., and Sugihara, G., “Cats protecting birds: modelling the mesopredator release effect.” Journal of Animal Ecology. 1999. 68(2): p. 282–292. http://deepeco.ucsd.edu/~george/publications/99_cats_protecting.pdf

23. Fan, M., Kuang, Y., and Feng, Z., “Cats protecting birds revisited.” Bulletin of Mathematical Biology. 2005. 67(5): p. 1081-1106. http://dx.doi.org/10.1016/j.bulm.2004.12.002

24. Bergstrom, D.M., et al., “Indirect effects of invasive species removal devastate World Heritage Island.” Journal of Applied Ecology. 2009. 46(1): p. 73-81. http://eprints.utas.edu.au/8384/4/JAppEcol_Bergstrom_etal_journal.pdf

25. O’Hara, T. (2007, April 3). Fish & Wildlife Service to begin removing cats from Keys refuges. The Key West Citizen.

26. n.a., Lower Florida Keys National Wildlife Refuges Comprehensive Conservation Plan. 2009, U.S. Department of the Interior, Fish and Wildlife Service: Atlanta, GA.

27. Clifton, M. Where cats belong—and where they don’t. Animal People 2003.  http://www.animalpeoplenews.org/03/6/wherecatsBelong6.03.html.

28. Patronek, G.J., “Letter to Editor.” Journal of the American Veterinary Medical Association. 1996. 209(10): p. 1686–1687.

29. Nogales, M., et al., “A Review of Feral Cat Eradication on Islands.” Conservation Biology. 2004. 18(2): p. 310-319. http://dx.doi.org/10.1111/j.1523-1739.2004.00442.x

30. Andersen, M.C., Martin, B.J., and Roemer, G.W., “Use of matrix population models to estimate the efficacy of euthanasia versus trap-neuter-return for management of free-roaming cats.” Journal of the American Veterinary Medical Association. 2004. 225(12): p. 1871-1876. http://www.avma.org/avmacollections/feral_cats/javma_225_12_1871.pdf

31. Hettinger, J., Taking a Broader View of Cats in the Community, in Animal Sheltering. 2008. p. 8–9. http://www.animalsheltering.org/resource_library/magazine_articles/sep_oct_2008/broader_view_of_cats.pdf

Inside Job

Results from the American Pet Products Association’s 2009­­–2010 National Pet Owners Survey suggest that cats in this country are spending more time indoors than ever before. Although the proportion of owners keeping their cats inside at night has remained relatively steady since 1998 (at approximately 66%), their has been a 14% increase in daytime confinement (from 56% to 64%) over the same period. [1]

Indoor&Outdoor Access-APPA

It must be noted that owners were asked where they usually kept their cat(s), thereby raising some doubts about the accuracy of their responses. (There are actually two issues here: first is the level of truthfulness—did owners, intentionally or not, provide accurate information? But there is also the obvious ambiguity surrounding the term usually.) Nevertheless, these results correspond reasonably well with those of two earlier surveys: one commissioned by the American Bird Conservancy (ABC) in 1997, [2] the other conducted by Clancy et al. in 2001 [3] (the only other surveys I’ve found that investigated this issue specifically).

The ABC’s study (in which 250 cat owners participated in a telephone survey) indicated that “35% keep their cats indoors all of the time,” while “31% keep them indoors mostly with some outside access.” [2]

The 2001 survey included 168 cat owners, each of whom was part of the Feline Health Study, conducted at the Foster Hospital for Small Animals, Cummings School of Veterinary Medicine, Tufts University. Sixty percent of these cats were “strictly indoor cats,” while 40% “had some level of outdoor access.” [3] Probing further, Clancy et al. discovered that nearly half of the cats with outdoor access were outside for two or fewer hours a day. And 29% of them were outdoors for less than an hour each day. [3]

Considering the differences in sampling (most notably the fact that participants in the 2001 survey were all clients of a veterinary hospital, whereas APPA survey results for 2000 indicate that 27% of cat owners did not visit the vet in the previous 12 months), and the inherent uncertainty surrounding the terms mostly, usually, and some, the results of these three surveys are remarkably similar.

Counting Cats
Such findings are critical for developing accurate estimates of the number of birds killed by cats (assuming a reasonable level of accuracy is achievable, given the complexity of the issue). Simply put, cats that don’t go outside can’t kill birds.

Recognizing this, some researchers have inflated their figures for cats allowed outdoors. [4–6]

Dauphiné and Cooper, [6] for instance, cite the APPA’s 2007–2008 survey when referring to the number of owned cats in the U.S., but either ignored or overlooked its findings about confinement: 63% of owners reported that they kept their cat(s) indoors during the day, 70% during the night. (It’s also possible that the authors consulted only the APPA’s online summary, which probably didn’t include this information.)

By contrast, Dauphiné and Cooper claim that 65% of pet cats “are free-ranging outdoor cats for at least some portion of the day,” [6] citing not the APPA survey, but Linda Winter’s 2004 paper, “Trap-neuter-release programs: the reality and the impacts” (which can be downloaded here). Indeed, Winter, the former director of the ABC’s Cats Indoors! campaign, had suggested as much—misrepresenting the findings of a study commissioned by her own organization:

“A 1997 nationwide random telephone survey indicated that 66% of cat owners let their cats outdoors some or all of the time.” [7]

Double the proportion of cats allowed outdoors, and—just like that—the number of birds killed by pet cats doubles too. (Dauphiné and Cooper actually go much further, employing some grossly inflated predation rates as well.)

Counting Birds
Of course, such estimates do not necessarily relate directly to population impacts. The predation may be largely compensatory, for example; and there are source-sink dynamics to be considered as well.

Nevertheless, researchers persist—more often, it seems, in pursuit of staggering, media-friendly figures than a better understanding of what’s actually going on (e.g., Dauphiné and Cooper’s bumper-sticker-worthy “one billion birds”). As a result, the scientific literature is plagued with some rather spectacular failures where predation numbers are concerned (e.g., The Wisconsin Study, Christopher Lepczyk’s dissertation, Carol Fiore’s thesis, etc.).

*     *     *

The surprising level of agreement among the three “outdoor access” studies provides researchers a rare opportunity to agree among themselves. Which, in turn, could move us closer to an honest debate of the larger issues—arguing about which action is most appropriate, for instance, rather than about whose numbers are most valid.

Despite how results of these surveys have been—as recently as last year—overlooked, ignored, and misrepresented, I remain cautiously optimistic. As Patronek has suggested, “predation of songbirds tends to be noticed because it takes place during the day.” [8] It’s time predation research received the same kind of visibility. Sunlight, after all, is said to be the best of disinfectants.

Note: There is a an amendment to this post here.

Literature Cited
1. APPA, 2009–2010 APPA National Pet Owners Survey. 2009, American Pet Products Association: Greenwich, CT.

2. ABC, Human Attitudes and Behavior Regarding Cats. 1997, American Bird Conservancy: Washington, DC. http://www.abcbirds.org/abcprograms/policy/cats/materials/attitudes.pdf

3. Clancy, E.A., Moore, A.S., and Bertone, E.R., “Evaluation of cat and owner characteristics and their relationships to outdoor access of owned cats.” Journal of the American Veterinary Medical Association. 2003. 222(11): p. 1541-1545.

4. Coleman, J.S. and Temple, S.A., On the Prowl, in Wisconsin Natural Resources. 1996, Wisconsin Department of Natural Resources: Madison, WI. p. 4–8. http://dnr.wi.gov/wnrmag/html/stories/1996/dec96/cats.htm

5. Lepczyk, C.A., Mertig, A.G., and Liu, J., “Landowners and cat predation across rural-to-urban landscapes.” Biological Conservation. 2003. 115(2): p. 191-201.

6. Dauphiné, N. and Cooper, R.J., Impacts of Free-ranging Domestic Cats (Felis catus) on birds in the United States: A review of recent research with conservation and management recommendations, in Fourth International Partners in Flight Conference: Tundra to Tropics. 2009. p. 205–219.

7. Winter, L., “Trap-neuter-release programs: the reality and the impacts.” Journal of the American Veterinary Medical Association. 2004. 225(9): p. 1369-1376.

8. Patronek, G.J., “Free-roaming and feral cats—their impact on wildlife and human beings.” Journal of the American Veterinary Medical Association. 1998. 212(2): p. 218–226.

The Scat Hits the Fan

Relative to other studies of the domestic cat’s predatory habits, Carol Fiore’s 2000 thesis work is cited only occasionally in the literature. [1, 2] Indeed, it might easily go unnoticed were it not for its inclusion in the American Bird Conservancy’s brochure Domestic Cat Predation on Birds and Other Wildlife, and the fact that Fiore posted a summary of the study on her website—making much of its content available to anybody interested in the topic.

Fiore’s “primary goal,” she writes, “was to estimate the number of cats in Wichita, the average number of birds killed per cat and the total number of birds killed by cats each year.” [3] In fact, there was more to it than that.

Fiore was also trying to quantify the number of birds killed by cats without their owners’ knowledge, thereby addressing a concern frequently expressed by researchers whose predation estimates rely on prey records kept by cat owners. [4–7] In other words, how many birds were being killed by cats, really?

Fiore’s thesis project was an ambitious undertaking—perhaps too ambitious. Although her goal was admirable, her small sample size, flawed analytical methods, and various confounding factors cast considerable doubt over her findings. In addition, Fiore’s thesis document is peppered with evidence of bias. Indeed, she raises questions about her motivation for the project (and underlying assumptions) when, early on, she refers uncritically to the ABC’s Cats Indoors! campaign and the Wisconsin Study, and mischaracterizes the work of William George (see Note 1).

I’m afraid that, in the end, Fiore’s work does little to enhance our understanding of the domestic cat’s hunting behavior. In fact, because her conclusions tend to misrepresent the study’s findings, Fiore actually does more to perpetuate the mythology surrounding predation than the science.

The Study
Fiore’s research incorporated several methods, each intended to provide a key piece of the predation puzzle:

  1. Twenty-eight Wichita, Kansas cat owners were recruited and asked to record the number and, when possible, also the species, of birds killed by their 41 cats over the period of approximately one year.
  2. Some of these same participants were asked to collect scat samples, which were then analyzed for feathers. Detection of feathers was used to account for kills not reported by cat owners.
  3. The behavior of eight participating cats was observed with the help of radio collars.
  4. Cat density in the area was estimated by combining telephone survey results (regarding the proportion of area cats that received the rabies vaccine) with information from local veterinarians (regarding the yearly total of rabies vaccines administered to cats).
  5. Using Christmas Bird Count data, the density of Northern Cardinals in the Wichita area was estimated.
  6. The impact of free-roaming cats on the population of cardinals was then estimated by combining findings from each of the investigations described above (with the exception of the radio collar monitoring).
  7. A second telephone survey was conducted, this time to learn about residents’ attitudes concerning possible cat regulations (e.g., leash laws, licensing, etc.).

Birds Brought Home by Cats
Twenty-nine (71%) of the cats were reported to have killed birds during the study period, while 12 (29%) were credited with no kills. (These figures would later be adjusted based on the results of the scat analysis, as described below.) However, multi-cat households posed a particular problem. “For owners with more than one cat,” writes Fiore, “kills were alternated between cats if the owner was unsure of the cat responsible.” [3]

As a result of her “alternating attribution” (my term, not Fiore’s) method, it’s possible that five cats were incorrectly included among the hunters (see Note 2 for details). If so, the proportion of hunters was not 71%, but 61%.

Other Studies
Either way, Fiore’s findings correspond reasonably well with those of a five-month survey of 618 British households, in which 986 cats brought home 14,370 prey items. This research revealed that, although 91% of cats returned at least one item, “approximately 20–30% of cats brought home either no birds or no mammals.” [5] Her results also seem to be in line with those published by Churcher and Lawton, whose yearlong “English Village” study (involving approximately 70 cats and 1,090 documented prey items) found that that 8.6% of cats brought home no prey [4] (though the authors don’t specify the percentage of cats that returned no birds).

On the other hand, it is not uncommon for such studies to find that more than half of the study cats returned no prey. In their pilot study of cat predation in Bristol (UK), for example, Baker et al. reported that 77 cats returned a total of 212 prey items to 52 participating households, but that “in each sampling period, the majority of cats (51–74%) failed to return any prey.” [6] Their subsequent 12-month study (this time involving 186 Bristol households, 275 cats, and 495 prey items) found a similar level of apparent non-hunters: roughly 61%. [7]

Any number of factors might contribute to these apparent differences, perhaps the most likely “culprits” being environmental (e.g., density of both birds and cats, habitat type and size, etc.) and sampling bias (as Baker et al. put it, “cat owners whose pets were killing lots of birds may have wished to hide the fact; alternatively, they may have been keen to show off their cat’s prowess.” [7])

Add It Up
Fiore began to quantify predation by calculating, based on the number of birds brought home by study cats, an average number of birds killed each year per cat. But, as I’ve discussed previously, using the average to describe predation rates (the distribution of which is highly skewed) overestimates the impact of cats on wildlife. Barratt offers a useful rule-of-thumb method (one echoed by Fitzgerald and Turner [8]) as an alternative:

“…median numbers of prey estimated or observed to be caught per year are approximately half the mean values, and are a better representation of the average predation by house cats based on these data.” [9]

Using the median—1.91 birds/cat/year—instead of the mean, cuts Fiore’s estimated predation rate of 3.44 nearly in half. (Among the more puzzling items I uncovered while reviewing Fiore’s thesis was her apparent miscalculation of the average predation rate—where Fiore comes up with 3.44 birds/cat/year, I get only 2.79. See Note 3 for a detailed explanation.)

In any case, what’s far more interesting is how Fiore adjusts her estimate based on the results of feathers discovered in scat.

Scat Analysis
Three of Fiore’s participants (who, together, owned six of the study cats) collected and bagged their cats’ scat for five consecutive days on a monthly basis. A fourth owner participated in this part of the study for just one month, and collected scat for three days.

Additional scat data was acquired via “litter box cleanups,” in which “a few volunteers were convinced to bag the entire contents of the litter box when it was cleaned.” [3] The results, according to Fiore, were rather dramatic:

“Out of 215 separate scat analyses, each of which could have composed several beakers of fecal material, feathers were found a total of 28 times. In only one instance, however, did the owner know that a bird had been killed and/or consumed.” [10]

Equally dramatic were the mathematical and statistical gymnastics Fiore employed to arrive at her conclusions. Her figure of 21%, for example, as “a mean value of the percentage of time a cat could be expected to ingest a bird with no owner knowledge,” [10] remains a mystery to me. Despite numerous attempts, I have been unable to sort out exactly how Fiore arrived at this figure.

Dividing 27 occurrences of “unexpected” feathers by 214 total analyses (subtracting in each case for the one instance of “expected” feathers) ought to get us close, it seems—but falls well short (12.6%).

Litter Box Cleanups
Of the 215 analyses, 24 were litter box cleanups, a data collection method plagued with problems. To begin with, only 11 owners (representing 19 cats) participated. Fiore acknowledges the limitations associated with this small sample size, but overlooks a thornier issue.

Fiore considered each cleanup—regardless of how many cats were using the litter box, or for how many days—a single data sample. If a feather was found during analysis (the details of which are described on Fiore’s website), then one additional kill was attributed to a single cat (again, alternating among cats in multi-cat households). While this is a conservative approach in one respect—no more than one bird could be recorded for any positive result—it fails to adequately account for the high number of negative results. A litter box containing the waste of three cats, accumulated over a period of five or more days (six of the 24 cleanups were of this type, and in only one case were feathers found), was treated no differently from one containing a single day’s waste from one cat.

This per-household approach allows a negative result in the first case to be offset by a positive result in the second—despite their very different implications.

On the other hand, at least two volunteers involved in the litter box cleanups also owned indoor cats, and it was impossible to determine whether it was their indoor or indoor/outdoor cats that were “contributing” to the study. This may have resulted in some false negatives.

Given all the uncertainty involved with Fiore’s litter box cleanups, it’s difficult to see how this aspect of her study contributes in any meaningful way to the overall findings. Better, I would say, not to include these results in any calculations—and perhaps disregard them entirely.

Monthly Collections
Fiore’s primary method (making up 191 of the 215 analyses) for scat analysis proved less problematic than the litter box cleanups—but was not without its own shortcomings.

Again, the sample size was quite small—only four participants in all (representing seven cats). And, once again, owners of multiple cats (two of the three long-term participants) were treated—from a statistical point of view—as if they each owned just one cat. A negative result in a three-cat household was weighted the same as an instance of feathers found in a single-cat household.

Worse, by alternating attributions of kills that could not linked to a specific cat in a multi-cat household, Fiore effectively makes hunters out of non-hunters (see Note 2 for a detailed explanation). In fact, given enough of these attributions—and it wouldn’t take many—all of the study cats would be categorized as killers.

Taking into account the number of cats in each household that participated in monthly collections (see Note 4), the number of scat analyses rises dramatically, from 215 to 354—and the average occurrence of feathers drops to just 7.6%.

Lucky 13
In the case of Cat 13—the study cat with the most “scat kills” (instances of feathers detected in scat when no birds were returned home) by far—feathers were found in 14 of 80 (17.5%) daily samples collected, prompting this reaction from Fiore:

“It is interesting to speculate as to the outcome of this study if all the volunteer owners had been as conscientious as this particular owner in collecting scat every month. Additionally this owner, who is retired, is very mindful of her cat’s whereabouts but still failed to find many kills.” [3]

But even Cat 13’s apparent penchant for secretive hunting yielded a frequency of found feathers well below Fiore’s suggested overall rate of 21%. And what about the other two long-term participants, whose 23 monthly samples (108 days’ worth—collected from five cats, not one, don’t forget) revealed just eight occurrences of feathers? Their frequency of secretive hunting was 7.4%—before accounting for the multiple cats involved (as described in Note 4), which would drop the rate to just 3%.

Was the owner of Cat 13 any more conscientious than the other two? Perhaps. Fiore notes that this woman, “appeared to be very serious about the study and never failed to turn in scat on a monthly basis; reminders were never required.” [3] Still, the other owners were hardly sitting on the sidelines—they turned in 108 samples between them. And it’s not clear what detrimental effect requiring a reminder might have had on the results; on the contrary, Fiore writes: “It is believed that scat volunteers conducted their collection correctly.” [3]

It’s difficult not to detect bias in Fiore’s praise for the diligence demonstrated by Cat 13’s owner—or, more to the point, her appreciation for the cat’s performance. Although this cat’s behavior is—as illustrated by Fiore’s own data—exceptional, Fiore seems to suggest that it’s the norm.

Corroboration and Disclaimers
Fiore is quick to point out various factors that would have allowed kills to go undetected by scat analysis. The condition of the birds recovered, for example, suggests that some cats don’t eat their prey, in which case scat would not have contained feathers. Nestlings, because they lack feathers, also would go undetected.

And even adult birds, suggests Fiore, may not have feathers to be discovered later. “Generally,” she writes, “cats pluck the feathers before consuming the bird.” [3] Although Fiore cites the work of other researchers on this point (work I’ve yet to chase down), her own findings seem to contradict this claim; plenty of feathers were found in scat. (Fiore’s claim also begs the question: If cats are expected to strip the feathers from the birds they kill, why use feathers found in scat as a measure of predation?)

Fiore is doubtful that “one of the study cats ate a bird it did not kill and that in turn feathers were detected in the scat,” [3] but Fitzgerald and Turner have suggested otherwise:

“Carrion is eaten, but is difficult to distinguish from animals killed by cats, unless it is from a large animal that a cat could not kill (e.g., sheep or kangaroo). Even the presence of maggots with the food is not a certain indicator, because cats may return later to prey they have killed and cached.” [8]

Although Fiore acknowledges the challenges inherent in her analysis method, she argues that they are outweighed by the benefits:

“Scat analysis is probably the most reliable estimate of bird kills, although it is a very conservative one. The results are hard to refute. When a feather is found it is proof that a kill was made or a carcass consumed… scat analysis is important because often cats do not bring their kills to the owner, and frequently the owner is not home to accept a kill should one be presented. Many of the owner volunteers reported not seeing their cat(s) for many days in a row (one owner did not see her cat for several months during the study). Collected kills were very conservative, and seemed to be based in part on the relationship of the owner with their cat(s). Unfortunately, absentee owners were the ones most unwilling to provide scat.” [3]

It seems Fiore wants to have it both ways: When it comes to defending the value of scat analysis, she’s quick to point out how much predatory activity the owners might be missing. When she’s emphasizing the conservative nature of prey tallies, though, Fiore cites a number of detailed firsthand accounts from cat owners—painting a rather different picture of owner involvement:

  • “There were numerous calls during the course of data collection about missing remains, cats seen eating birds but no remains could be found, cat running off with prey…”
  • “The wife of one of the volunteers admitted to seeing her cat drag a cardinal under the porch, but she would not retrieve it…”
  • “The owner of Cat 30 reported that she had seen… her cat eat an entire bird (even the head) and that there was no evidence left to give us.”

Her inconsistency raises questions not only about her findings, but also—far more unsettling ones—about her objectivity as a researcher.

Found Feathers
Despite results that are—at best—mixed, Fiore’s conclusions are imbued with certainty and drama. They also tend to misrepresent her research. Fiore’s claim that “scat analysis may indicate, as in this study, that a far greater number of birds are consumed than was previously thought” [3] is based on her misuse of means to characterize predation levels. Using medians instead, it becomes clear that—in terms of the distributions’ central tendency—there is no difference between her original data set and the one that includes scat kills.

More problematic, though, are Fiore’s claims about the secretive hunting habits of cats:

“Probably the most important information which can be gained from the scat analysis (coupled with owner bird collection) is that most cats do kill birds. And in all cases but one, when feathers were found in scat, the owner was unaware that the cat had eaten a bird. This and other data from this study would seem to refute Dr. Patronek’s claim that ‘cats tend to bring prey home.’” [3] (See Note 5 for details regarding Fiore’s apparent dispute with Patronek.)

Actually, Fiore’s own data indicate that cats do, in fact, “tend to bring prey home”—nearly four in five, if her mysterious 21% figure is to be believed. And her assertion about the surprising nature of kills revealed through scat analysis is—although technically true—highly misleading. She seems to be suggesting that scat collection was done randomly, in which case we would expect some collections to correspond with documented kills. Fiore’s reporting, however, indicates no such randomness. In fact, it’s entirely likely that participants (thinking such activity would at least be redundant, or worse, detrimental to the study) would have collected scat only when they were unaware of their cat(s) having killed a bird.

By framing her findings this way, Fiore effectively dismisses the vast majority of analyses (187 of 215, or 87%, using her analysis method; 326 of 354, or 92%, accounting for multi-cat households) in which no feathers were found.

When the ABC summarizes Fiore’s work in their brochure Domestic Cat Predation on Birds and Other Wildlife, they only make matters worse by conflating different aspects of her research:

“In a study of cat predation in an urban area, 83% of the 41 study cats killed birds. In all but one case, when feathers were found in scat, the owner was unaware that their cat had ingested a bird. In fact, the majority of cat owners reported their cats did not bring prey to them. Instead, the owners observed the cats with the bird or found remains in the house or in other locations.” [11]

Reading the ABC’s version, one might easily get the impression that all 41 cats were involved in the scat analysis, or that the scat collections were done randomly. (Or that cats, in order to be considered cooperative participants in predation studies, are expected to deposit their prey in the laps of their owners, or some other pre-determined location.)

Connecting the Dots
Let’s set aside my (numerous) complaints regarding Fiore’s scat analysis, and my claim that she both miscalculated and misused the average predation rate. Assuming both figures are valid, Fiore’s use of that 21% figure to adjust the predation rate upward, from 3.44 to 4.2 birds/cat/year is also a problem. The scat analysis should (again, assuming it was done properly, included sufficient sample sizes, etc.) reveal something about the secretive hunting behavior of the study cats—in terms of (1) its frequency, and (2) its extent. Fiore’s misstep is in linking the frequency directly to predation levels.

Properly adjusting the estimated predation level would involve, first, correcting the proportion of cats that hunt to account for the frequency of secretive hunters. Using Fiore’s data to illustrate:

71% + [(100%-71%) x 21%] = 77%

Once we adjust for those cats that don’t bring prey home, we can multiply this figure by the number of outdoor cats (see Note 6). Again, using Fiore’s data (described in the Cat Density section below):

40,836 pet cats x 43% allowed outdoors = 17,559 hunting cats

Multiplying this result by the median predation rate (1.91), we get a total of 33,538 birds/year killed by pet cats in Wichita—less than half Fiore’s estimate of 73,750. (This figure might be refined further by considering separate predation levels: one for the secretive hunters, and another for those cats known to bring prey home. Unfortunately, Fiore’s sample size is too small to make such a comparison, but it’s not difficult to imagine different hunting behaviors resulting in different success rates.)

To reiterate, I’m using Fiore’s numbers here only to illustrate how I would connect the dots between scat analysis results and predation levels.

Two Key Points
Fiore’s goal of obtaining a more accurate tally of birds killed by cats was (and is) admirable. However, her use of scat analysis was largely unsuccessful in achieving that goal. In fact, Fiore’s analysis method actually added to the uncertainty in two important ways:

  1. By alternating attributions of kills that can’t be linked to any one cat in a multi-cat household, Fiore essentially categorizes each one of them as a hunter.
  2. By weighting multi-cat households no differently from single-cat households, Fiore ignores a great deal of evidence suggesting that most cats are not, in fact, hunting without their owners’ knowledge. Although the number of “scat kills” is conservative as a result, her analysis method gives greater importance to what is unknown than to what is known.

Radio Tracking
Among the many challenges Fiore ran into while trying to track study cats were owner objections, physical barriers (e.g., fences), and radio signal strength/continuity in an urban setting. As a result, she was able to study only eight cats for a total of 57 hours (almost all during daylight hours).

Given the limited value of Fiore’s tracking activities—and my focus on the aspects of her thesis that pertain more directly to predation—I’ll move on to her estimate for the number of cats in Wichita.

Cat Density
Fiore used two different methods to estimate the number of cats in Wichita. The first, which is rather clever, involved combining the results of two telephone surveys: the Pet Ownership Survey was used to (among other things) poll respondents about whether or not they had vaccinated their cat(s) against rabies; a survey of local veterinarians was used to estimate the annual total of such vaccinations in Wichita. “If 500 cats received vaccinations,” writes Fiore, “and respondents indicated that 50% of pet cats had been vaccinated, 1000 cats would be the expected density.” [10]

For the second method, Fiore multiplied the number of Wichita households by the estimated number of cats per household (1.52), as determined through a random telephone survey.

Results of the first method yielded an estimate of 35,737 pet cats in Wichita, whereas the second method produced an estimate of 40,836 pet cats. (The skewed nature of the cats/household distribution (many owners having one or two cats, and a few having many cats) will tend to push such estimates upward.)

In addition, Fiore estimates (in her original thesis document, but not in the summarized version that appears on her website) the number of stray and feral cats in the city, ultimately arriving at a figure of 124,537. Deriving such estimates is always dodgy work, as so little trustworthy information is available. Additional caution is in order when these figures are used to project predation levels of stray and feral cats, as Fiore has done (as described in the Christmas Bird Count section, below).

For one thing, there are some questionable assumptions wrapped up in her estimates—not the least of which is that the predation rates and patterns of stray and feral cats are similar to those of pet cats. Clifton has suggested that they are not:

“The feral cat toll on birds is unlikely to be more than half as high as the pet cat toll. First, there may be twice as many free-roaming pet cats as ferals old enough to hunt for a living. Second, ferals who hunt for a living tend to hunt mice by night, not birds, who are mostly not out at night. Third, feral cats appear to hunt no more, and perhaps less, than free-roaming pet cats. This is because, like other wild predators, they hunt not for sport but for food, and hunting more prey than they can eat is a pointless waste of energy… Finally, relatively few cats are even capable of successfully hunting birds.” [2]

Christmas Bird Count
Fiore used data from the Wichita Audubon Society’s “first area-wide bird count of Northern Cardinals,” [3] an event coinciding with the National Audubon Society’s 99th annual Christmas Bird Count. Combining this data with the number of households in the city, she estimated that there were 316,477–424,922 cardinals in Wichita at the time.

It’s important to remember, as is made clear on the North American Breeding Bird Survey website, that such surveys provide “an index of relative abundance, rather than a complete count of breeding bird populations.” Fiore admits, “a census of a single bird species effected [sic] by urban cats in Wichita is an estimate of population density within an accuracy of one order of magnitude,” [3] but persisted.

As a result, Fiore was able to compare estimates of the overall cardinal population with estimates of those killed by cats. However, her “accounting practices” suggest that she’s not exactly impartial on the subject of predation. Fiore states unequivocally, for example, “the mean of 2.98… cardinals seen per residence is high as very few surveys were returned by people who saw no cardinals.” [3] Sure that “people only reported when they saw cardinals, thus skewing the data towards high values,” Fiore discards the mean and uses frequency quantiles instead.

Among the possible sources of participant bias Fiore cites:

“…adding counts together rather than reporting total numbers seen at one time, counting birds on someone else’s property, estimating numbers by song alone, or sending in the forms with numbers that did not exist on December 19 but that the resident had seen on some previous occasion.” [3]

Perhaps she was correct in her assessment, but it’s peculiar that Fiore never expressed a similar concern for her obviously skewed distribution of birds killed by cats—and as a result, overestimated predation levels. In short, she seems determined to lower the estimate of birds in the area while at the same time raising the estimate of birds thought to be killed by Wichita’s cats. (In fact, her thesis is littered with such maneuvering; Fiore uses nearly every instance of uncertainty to imply an impact on wildlife greater than her research actually suggests.)

Fiore’s bird collection data indicated that 7% of the birds taken were Northern Cardinals. Combining this figure with her estimates of the populations of all outdoor cats and cardinals in Wichita, she concludes, “there are at least 43,035–50,285 Northern Cardinal deaths per year due to cat predation.” [3] This corresponds to roughly 15% of her estimated cardinal population—a figure Fiore describes as “extremely conservative.”

Impact of Free-roaming Cats
Considering the numerous limitations of her study (many of which she acknowledges), Fiore seems quite comfortable extrapolating her results—arguing, for example, that “over half a million birds meet their death each year in the city of Wichita because of a cat.” [3] Of course, this figure relies on dubious estimates of the number of outdoor cats, an exaggerated predation estimate, and other factors that cast serious doubt on its accuracy.

Fiore’s confidence may come, in part, from the fact that other researchers have reported similar findings. But, as I have gone to great lengths to emphasize over the past few months, such findings rarely hold up to careful scrutiny. And sometimes, results are simply misunderstood—as when Fiore misinterprets Fitzgerald’s work:

“…several studies have been done to access [sic] the importance of birds as a percentage of total diet, as in Fitzgerald [12] who estimates birds represented 21% of cat diets.” [3]

In fact, Fitzgerald was referring not to the percentage of dietary intake, but of how often birds were found in scat or stomach contents (a distinction I explain in detail here):

“On all continents, birds are usually much less important than mammals; birds were present on average at 21 per cent frequency of occurrence, and mammals at 68 per cent. Many species are represented by just one or two individuals.” [12]

Something else Fiore overlooks is that the type of predation observed by her participants may have been largely compensatory; that is, the birds killed were of sufficiently poor health that they were unlikely to survive anyhow. Two studies have reported such findings. [7, 13] If this were the case, even her inflated estimates—however dramatic sounding—would actually have little impact on the population of Wichita’s birds.

In any case, the cardinals in the area seem to be doing fine. Between 1970 and 2000, Wichita’s human population increased 24.5%, from 276,554 to 344,284. Such an increase—accompanied by various related development activities—is generally associated with habitat loss, fragmentation, pollution, and any number of other factors that adversely affect bird populations. Including more cats. Nevertheless, data from the North American Breeding Bird Survey suggests that the number of Northern Cardinals in the area was on the increase over this period.

Wichita Cardinals Over Time
Caption: BBS Data: Northern Cardinals for Three Wichita-area Survey Routes (adapted from North American Breeding Bird Survey website)

Cat Regulations
Fiore used a telephone survey of Wichita residents to inquire about a range of pet ownership issues, as well attitudes concerning possible regulations affecting cats/cat owners. Among the questions Fiore posed to Wichita pet owners:

“At the present time dogs have to be licensed and kept on leashes. How do you feel about having cats regulated so that they would have to be licensed and confined to the owner’s property?”

Thirty-one percent of cat owners were completely opposed, while 44% said they were at least somewhat in favor—“a surprisingly high figure,” as Fiore notes. Pet owners were then asked a follow-up question:

“If it were found that unregulated cats are killing too much wildlife, would you change your opinion?”

Survey results are always tricky to interpret, and two people can often draw very different conclusions from them. Rather than focus on the responses, then, I’d like to take just a moment to focus on the question—starting with the term unregulated. Is that even necessary? How about simply cats? And what do me mean by wildlife here? And how much is too much?

Nearly half of respondents said that they would not change their minds, and Fiore sounds downright exasperated with their explanations:

“Cat owners are in denial about what their cats are doing. They seem sad over the death of a cardinal, but they refuse to take responsibility for the cat by stating ‘There is nothing I can do’ or ‘…but that’s what cats do.’ The owner of study cat 14 wrote ‘Cats are part of nature same as birds. Species come and go. I don’t think nature should be artificially regulated.’” [3]

Fiore clearly disagrees. Indeed, she tipped her hand much earlier, when, in Chapter 1, she wrote:

“If a human killed any of these birds or was caught in possession of them without a valid permit, he or she would face penalties including fines, and depending on the severity and species, possible jail time. Cats across America and their owners face no punishment.”

*     *     *

A story in the April 18, 1998 edition of The Wichita Eagle explained Fiore’s proposed project this way:

“Fiore, a graduate student at Wichita State University, will spend a year counting Wichita cats and their feathered victims for her master’s thesis. As bird populations decline, Fiore thinks it’s important to know how far cats are sinking their teeth into the feathered world… She points out that even the cutest kitty can be a remarkable hunter, although skill varies from cat to cat. But Fiore doesn’t want people to think she’s anti-cat. ‘I’m out to study the problem.’” [14]

In the same piece, Fiore brings up the Wisconsin Study (referring to its “intermediate value” of 39 million birds), and it’s revealed that she’s the vice president of the Wichita Audubon Society. Nevertheless, Fiore assures readers of her objectivity: “We’re just scientists who want to see if there’s a problem.”

Fiore’s thesis dedication, too, suggests an air of integrity and goodwill:

“This thesis is dedicated to my cat owner volunteers who made this study possible and to cat lovers and bird lovers around the world in the hopes that we can all work together to preserve native wildlife.” [3]

Having spent weeks reviewing Fiore’s work, though, I’m not buying it. In fact, I can’t help but read in her dedication an inside joke of sorts: her invitation is to preserve native wildlife; domestic cats, as she makes clear elsewhere, are not native.

In a follow-up story for The Wichita Eagle, Fiore reported her results: Wichita cats kill anywhere from 542,000 to 645,000 each year. But, according to the Eagle’s Roy Wenzl, it wasn’t the results that got some residents worked up. “Fiore’s study upset people. Not what she found. But what she did, in raising the question.” [15]

“‘I didn’t understand that,’ said Bob Gress, a cat owner, a naturalist and the director of the Great Plains Nature Center, who helped her with her study. ‘All she was doing was collecting information. I don’t think any of us should ever be afraid of the truth,’ Gress said. ‘But some people saw this as an assault on cats. Even some veterinarians seemed to resent what she was doing.’” [15]

Gress’ comment got me thinking not just about Fiore’s thesis, but also about how it’s been used—primarily by the ABC. As much as we might like to believe otherwise, scientific inquiry doesn’t happen in a vacuum; there is always a context to consider. It’s clear from her document that Fiore was well aware of the debate surrounding free-roaming cats at the time—and must have a good idea, too, of the possible implications of her work (e.g., ammunition for those who oppose free-roaming cats and TNR, the possible wholesale extermination of stray and feral cats, etc.).

And then there’s the matter of just how much truth there is in Fiore’s findings—plagued as they are by her flawed analysis and obvious bias.

Which is not to say that she (or anybody else) should be discouraged from studying such complex, controversial issues. But there is a great responsibility that comes with such endeavors. Fiore, in her thesis work, simply didn’t live up to that responsibility.

1. Fiore writes: “A researcher in southern Illinois estimated that his three house cats, which he followed for 6 years, only brought home about 50% of killed prey.” [16] As I’ve pointed out previously, this is a surprisingly common misunderstanding of George’s work. In fact, George was merely adjusting predation levels based on the fact that the “delivery area” was not always monitored: “…the study registered 50 percent of the cats’ captures—a percentage roughly corresponding to: 1, the average amount of total time the delivery area was under observation for recording prey; and 2, the number of prey items logged in the same year when the delivery area was under continuous day-and-night scrutiny, compared to the number logged (during equivalent seasonal and hourly periods) when continuously scrutinized for lesser amounts of time.” [16]

2. Fiore provides little detail regarding the application of her alternating attribution method, requiring some speculation on my part. An example, however, may prove illustrative. Consider Cats 17 and 18, which lived in the same home. During the bird collection phase of the study, Cat 17 was credited with just two kills. Cat 18, on the other hand, brought home 17 birds—clearly the more successful hunter. The question is: Did Cat 17 really kill those two birds, or are these simply the result of kills that could not be attributed to either cat?

At any time during the yearlong study, kills that could not be connected directly to a particular cat were, as Fiore explains, “alternated between cats.” Imagine if, at the time Cat 17 had 15 known kills, another kill was discovered—but this time, it was unclear which cat was responsible. That kill, then, would be attributed to Cat 17, bringing its total to 16. The next such kill would be attributed to Cat 18—effectively shifting its status from non-hunter to hunter. Two more such instances would yield the results described by Fiore: two kills for Cat 17 and 17 for Cat 18—though it should be clear that just two “mystery kills” would, using Fiore’s analysis method, create the impression that both cats are hunters. (In fact, were it not for their random numbering—Cat 17 being credited with the first “mystery kill” only because of its lower ID number—such an impression would result from just one such kill.)

To be clear: the scenario described above is speculative. But, given the impact of Fiore’s alternating attributions—increasing rather dramatically the proportion of apparent hunters—careful scrutiny is warranted.

3. Calculating the mean should be quite straightforward, of course. Fiore first calculated a daily rate for each cat by dividing that cat’s catch by the number of days in which its owner participated in the study. She then averages that rate over all 41 cats (coming up with 0.0094, compare to my 0.0076), and multiplies the result by 365 days/year.

4. Using this analysis method, a five-day collection from a three-cat household would constitute not five, but 15 analyses. Now, there’s no way of knowing that all three cats contributed to the scat collection; conversely, there’s no reason to think that just one cat contributed, as Fiore assumes.

5. At times, Fiore’s thesis reads as if it was a rebuttal to Gary Patronek’s article, Free-roaming and feral cats—their impact on wildlife and human beings, which was published around the time Fiore was conducting her research. Interestingly, had Fiore read Patronek’s paper more closely, she might not have used the mean to estimate predation rates. “The small proportion of cats with a large number of kills,” writes Patronek, “indicate that the number of animals killed per cat has a skewed distribution, which would tend to bias the mean upward.” [17]

6. Fiore is skeptical of her Pet Ownership Survey results, which indicate that 43% of cat owners keep their cats indoors (“People who interpreted this question to mean that because the cat was inside ‘most of the time’ it was an indoor cat, would be incorrect for purposes of this study.” [10]). However, as Merritt Clifton points out, it’s likely that she actually overestimates the number of outdoor cats when she “decided, based on a survey of Wichita residents, that about half of all cat-keepers allow their cats to roam, and presumed that could be extrapolated to mean that half of all pet cats roam.” This, writes Clifton, contradicts Animal People findings “that cat-keepers whose cats do not roam have, on average, from two to three times more cats than those whose cats can roam.”  [2] Further support comes from a 2003 survey that found 60% of cats were kept strictly indoors, and nearly half of those allowed outdoors were out for less than two hours each day. [18]

Literature Cited
1. Dauphiné, N. and Cooper, R.J., Impacts of Free-ranging Domestic Cats (Felis catus) on birds in the United States: A review of recent research with conservation and management recommendations, in Fourth International Partners in Flight Conference: Tundra to Tropics. 2009. p. 205–219.

2. Clifton, M. Where cats belong—and where they don’t. Animal People 2003 [cited 2009 December 24].  http://www.animalpeoplenews.org/03/6/wherecatsBelong6.03.html.

3. Fiore, C.A., The Ecological Implications of Urban Domestic Cat (Felis catus) Predation on Birds In the City of Wichita, Kansas, in College of Liberal Arts and Sciences. 2000, Wichita State University: Wichita, Kansas

4. Churcher, P.B. and Lawton, J.H., “Predation by domestic cats in an English village.” Journal of Zoology. 1987. 212(3): p. 439-455.

5. Woods, M., McDonald, R.A., and Harris, S., “Predation of wildlife by domestic cats Felis catus in Great Britain.” Mammal Review. 2003. 33(2): p. 174-188.

6. Baker, P.J., et al., “Impact of predation by domestic cats Felis catus in an urban area.” Mammal Review. 2005. 35(3/4): p. 302-312.

7. Baker, P.J., et al., “Cats about town: is predation by free-ranging pet cats Felis catus likely to affect urban bird populations? Ibis. 2008. 150: p. 86-99.

8. Fitzgerald, B.M. and Turner, D.C., Hunting Behaviour of domestic cats and their impact on prey populations, in The Domestic Cat: The biology of its behaviour, D.C. Turner and P.P.G. Bateson, Editors. 2000, Cambridge University Press: Cambridge, U.K.; New York. p. 151–175.

9. Barratt, D.G., “Predation by house cats, Felis catus (L.), in Canberra, Australia. II. Factors affecting the amount of prey caught and estimates of the impact on wildlife.” Wildlife Research. 1998. 25(5): p. 475–487.

10. Fiore, C.A. and Sullivan, K.B. (2000) Domestic Cats (Felis catus) Predation of Birds in an Urban Environmenthttp://www.carolfiore.com/Article.html Accessed July 27, 2010.

11. ABC, Domestic Cat Predation on Birds and Other Wildlife. n.d., American Bird Conservancy: The Plains, VA. www.abcbirds.org/abcprograms/policy/cats/materials/predation.pdf

12. Fitzgerald, B.M., Diet of domestic cats and their impact on prey populations, in The Domestic cat: The biology of its behaviour, D.C. Turner and P.P.G. Bateson, Editors. 1988, Cambridge University Press: Cambridge; New York. p. 123–147.

13. Møller, A.P. and Erritzøe, J., “Predation against birds with low immunocompetence.” Oecologia. 2000. 122(4): p. 500-504.

14. Potter, T., Counting Cats and Their Winged Prey, in Wichita Eagle, The (KS). 1998. p. 9A

15. Wenzl, R., Are You Harboring a Killer on Your Couch?, in Wichita Eagle, The (KS). 1999. p. 9A

16. George, W., “Domestic cats as predators and factors in winter shortages of raptor prey.” The Wilson Bulletin. 1974. 86(4): p. 384–396.

17. Patronek, G.J., “Free-roaming and feral cats—their impact on wildlife and human beings.” Journal of the American Veterinary Medical Association. 1998. 212(2): p. 218–226.

18. Clancy, E.A., Moore, A.S., and Bertone, E.R., “Evaluation of cat and owner characteristics and their relationships to outdoor access of owned cats.” Journal of the American Veterinary Medical Association. 2003. 222(11): p. 1541-1545.