All animals, whether wild or domestic, deserve to be treated in a kind manner. That is why we support the actions of compassionate individuals who feed, spay, and care for feral cats. But feral cat caretakers and their allies are increasingly coming under attack by misinformed native species advocates who blame cats for a perceived decline in local wildlife, that is of no fault of the cats.
Every major, reputable study has shown that claims of cat predation affecting bird and wildlife populations are wholly overstated. In fact, all the studies we have seen have shown that in Golden Gate Park, and throughout our city, the true factors that account for the disappearance of quail and other wildlife are habitat loss, pollution, and inclement weather changes.
The reasons for this are well–documented. As human development continues in our already crowded cities, available habitat for wildlife is carved up into smaller and smaller pieces. Habitat fragmentation and marginalization cause wildlife populations to become genetically separated, and if a particular population is not large enough, remnant populations are subject to genetic inbreeding. As a result, as habitat declines, so does diversity and heterogeneity, resulting in high extinction rates.
Under such circumstances, harsh winters or long periods of drought can easily drive down remaining populations. As all living things are dependent on water, the six–year period of drought in California during the 1980s and early nineties had a devastating effect on wildlife mortality and clutch success.
Pesticides are also recognized as a major culprit in bird decline––particularly the effect of toxic lawn care products in the decline of the songbird. Insecticides, herbicides, fungicides, and rodenticides are routinely used in City parks. Indeed, poisoning as a result of the everyday use of pesticides has become so wide–spread that biologists term the phenomenon “lawn–care syndrome.” Other practices, such as removal of low growing shrubbery, tree trimming, and the lack of adequate maintenance at many City parks will also impact on birds and other wildlife.
A 1994 World Watch Institute study showed, for example, that of the world’s 9,000 bird species, 5,000 are in decline, while another 1,600 are threatened or nearly threatened with extinction. Some populations have fallen by 75% as a result of four primary factors: habitat loss, overtrapping, drought, and pesticides. Cats are noticeably absent as factors.
With regard to predation, cats are widely recognized to have low success at bird predation. Studies by biologist Robert Berg in Golden Gate Park in San Francisco showed, in fact, that any feral cat predation would actually occur on the rat population in the park, increasing quail strength, because it lowers nest predation by rats. Roger Tabor’s famous studies of cat predation in Great Britain and the United States show that the great bulk of an unfed feral cat’s diet is scavenger material such as garbage, insects, plants, and rats, finding no impact on continental bird and wildlife populations. Indeed, studies on four continents reach the same conclusion—“[t]he common belief that feral cat are serious predators of birds is apparently without basis.”
In San Francisco, City officials recognized and acknowledged that cats are not responsible for bird decline and the county Board of Supervisors’ Commission on Animal Control and Welfare put a stop to a proposed round up and kill plan for feral cats in Golden Gate Park after extensive research and public testimony demonstrated a clear lack of evidence that cats were impacting birds.
Given the available evidence to the opposite, we believe it is both incorrect and inappropriate to speculate that cats are a significant cause for bird species decline. In addition to the San Francisco studies, predation studies on four continents (Europe, North America, Australia, and Africa) conclude feral cats should not be implicated in any perceived decimation of local wildlife.