• Susan Houser

The Commensal Cat

Cats are commensal animals. This fact has some very important implications for trap-neuter-return (TNR) and for the battle to save cats from bird conservationists.



The mesocarnivores who live in a commensal or mutual relationship with humans generally combine scavenging with predation in order to survive. Their populations differ from populations of wild animals in several respects, including higher numbers, smaller territories, opportunistic feeding, and a tolerance of human presence. The literature about the domestic cat in the United States contains very little information on the implications of commensalism. Most studies on control of feral cat populations and cat predation seem to assume the commensal nature of the cat without really addressing its implications. This is a mistake, because management of commensal species is, or should be, completely different from management of populations of wild animals who seek to avoid contact with humans. The commensalism of the domestic cat presents us with both problems and opportunities in controlling their numbers.

There is so little that has been written specifically about commensalism in domestic cats that I had difficulty finding anything that was available to the general public on the issue. I finally found an excellent book by an English professor of archeology, Terry O’Connor, that deals with the subject of commensalism in general and has a section on cats. The book is called “Animals as Neighbors: The Past and Present of Commensal Species.” Although the book does not connect the dots between the commensalism of the cat and control techniques such as TNR and Return-to-Field (RTF), it does provide a broad general background on commensalism itself – how it developed over human history and where the various types of commensal animals fit into the scheme.

As O’Connor notes, feral cats “rely on our built environment and garbage for protection and food.” In other words, feral cats thrive in environments where there are a lot of vacant, unused structures and accessible trash. This has been confirmed by ecological studies that were done in Baltimore and Brooklyn in the 1980s. So what does this mean for our feral cat programs?

First and most obviously, feral cat overpopulation is primarily an issue of the urban environment, specifically the blighted urban environment. Although feral cats can certainly exist in the wild by hunting, that does not appear to be their preferred habitat. In the wild, food becomes much more of a limiting factor for cats. Therefore, if we solve the problem of feral populations in the cities, we will have solved the great bulk of the overall problem. There are many people who argue that TNR is not the answer to the feral cat problem because we cannot possibly do TNR on enough feral cats to make a difference. Yes we can. We just need to concentrate on the areas where conditions exist that can maintain a large feral population, which means blighted urban environments. We do not need to do TNR on every feral cat in every jurisdiction in the United States to solve the problem, because in places where empty buildings and garbage are not available feral cat populations are likely to be self-limiting.

Second, we might want to see if we can coordinate TNR with programs to reduce urban blight. This will not only attack the problem at the roots, but it re-directs the public’s attention away from the feral cat “problem” and to the conditions from which the problem originates – the availability of empty structures and garbage. As an added benefit, attacking urban blight will reduce the rat population too. Simply removing cats from an urban area where they are thriving will likely result in a large increase in the rat population, since the same conditions favor both species. Coordinating blight-reduction measures with TNR could mean that colony caregiving must begin to include managed shelter as well as managed food sources.

Third, we need to confront bird conservationists with the implications of commensalism. As O’Connor discusses at length, birds are commensal species too. Some of the most successful commensal birds are pigeons, sparrows, and crows. Bird conservationists, oddly enough, are not interested in saving pigeons, sparrows, and crows from cat predation. In fact, they appear to hate the successful commensal birds as much as they hate cats. This is strong evidence that bird conservationists are more concerned about their view of “nature” than about animal welfare. Crows are among the most intelligent animals on the planet, yet bird conservationists tend to see them solely as pests. The idea that the life of an individual animal has value seems very foreign to the thinking of the typical bird conservationist.

Not all types of birds are commensal, and some live in the wild far from humans. These are often the rare species that bird conservationists love – not for themselves as individuals, of course, but because they represent that ideal, pristine version of nature that conservationists value. As far as I can tell, there have been few if any studies on feral cat presence in remote, wild regions of the United States like the swamps of Louisiana. I suspect that is because there are few feral cats in areas that are truly remote from human habitation. (The exception is on some oceanic islands where cats have been introduced and then the humans left, but that is a whole different story.)

So bird conservationists are barking up the wrong tree, so to speak, when they blame feral cats in the United States for killing the type of birds they care about. Since feral cats live primarily as scavengers in human settlements, the birds they kill are very likely to be the commensal species that bird conservationists hate anyway. Feral cat supporters need to press bird conservationists to be more specific about just what birds cats are killing. Are they killing bluebirds and goldfinches, or pigeons and sparrows? Is there decisive evidence that, in the United States, cats are a significant predator of rare bird species? And if such evidence is lacking, then they need to, in the immortal words of Trey Gowdy: “Shut up talking about things that you don’t know anything about.”

No Kill advocates, unlike bird conservationists, care about the lives of all animals, including starlings, pigeons, and crows. That is why we advocate for TNR, because managed cat colonies reduce whatever bird predation may exist (since managed colonies are provided with food) while also preserving the lives of the cats.

Feral cat advocates have some very strong arguments available to us in favor of TNR. We need to start pushing back harder on the bad science that bird conservationists have been rolling out to support their “kill cats” agenda. We need to stop trying to address their inadequate studies one by one and develop our own comprehensive picture of the relationship between cats and birds. One of the components of our picture should be that cats and birds co-exist extremely well in the suburbs (see my blog post about cats in the suburbs). Another should be that cats in urban areas, to the extent that they are preying on birds at all, are likely preying on commensal bird species that are not endangered and that many people regard as pests. Another part of the picture should be that the cat, since it is a commensal animal, is a highly unlikely predator of the rare bird species that live in areas remote from human habitation. And the final piece of the puzzle is that since cats are commensal, TNR can work to control populations where control is needed most.

Bird conservationists have for the most part been getting a free ride with their simplistic claim that “cats kill birds, therefore cats are bad for bird populations.” They have even had the cheek to ask the taxpayers to fund their “kill cats” programs. Feral cat advocates have been slow to push back on the science because we, for the most part, are not scientists. That needs to change. As Bob Dylan said: “You don’t need a weatherman to know which way the wind blows.”

0 views