A debate rages in Salem over the environmental impacts of the feral cat population.  In the February issue of Salem Audubon’s newsletter, Ray Temple and Doug Spencer aptly define the two positions as, “concerns for bird populations by predation” on one side, and “the humane treatment of cats that no one owns” on the other.

The Humane Society of the United State estimates there are more than 70 million stray and feral cats in the United States.  Temple and Spencer observe that in the wild the animals “have short, risky and often unpleasant lives due to disease, predation and starvation,” Though they dont explicitly recommend euthanasia, they suggest that people concerned with wildlife loss discuss with a veterinarian options for humane euthanasia.

Salem is also the home of the Coalition Advocating for Animals (CAFA,), which, among other animal work, helps local people feeding stray cats with spay and neuter assistance.  CAFA strongly believes in trap/neuter/release (TNR) a policy in which people trap unowned cats, have them neutered and return them to the wild.  The group calls TNR “the most effective way to work with feral or free-roaming cats.”

In contrast with Temple and Spencer’s statement that neutered cats “are still bird predators,” CAFA cites a 2011 Australian study which showed that when feral cats were eliminated from islands off Australia, the rodent population of rats and rabbits exploded.  This severely impacted birds living there because rats ate bird eggs and fledglings, and rabbits ate ground cover and nesting materials.

Alley Cat Allies is the largest national organization to back the TNR effort.  Alley Cat Allies argues cats have lived out doors for more than 10,000 years and are a “natural part of the landscape.”

Citing evidence from scientific studies, Alley Cat Allies says most feral cats find food by scavenging, mostly on human garbage, rather than killing songbirds, and when they hunt, kill mostly rodents.  They say a 2011 Smithsonian Institution study suggesting that feral cats kill too many wild birds is “irresponsible” and “biased.”

Though Alley Cat Allies agrees with the documented drop in wild bird populations, it blames “humans and human-led activities, including habitat loss, pollution and climate change,” rather than cats.  Its Facebook pages includes tips on how to keep unowned cats warm in winter, outdoor feeding stations and other strategies to support feral animals.

Peer-reviewed science does not support both feral cat TNR and feral cat euthanasia as equally valid options.

World Conservation Union, an international group, included domestic cats in its list of “100 of the Worlds Worst Invasive Alien Species.”  Species were selected, among other things, “on the basis of their serious impact on biological diversity.”

A 2009 Los Angeles study compared arguments of “feral cat advocates with scientific literature,” and found that “the scientific literature contradicts each of,” the most common claims used by TNR proponents.

Most significantly, the Smithsonian Institution’s Migratory Bird Center and the U.S. Fish and Wildlife Center assembled a comprehensive review of every U.S.-based cat predation study (excluding Hawaii and Alaska) in the scientific literature.

Published in December 2013, the study quantified bird and small mammal mortality.

“We estimate,” it concluded, “that free-ranging domestic cats kill 1.3–4.0 billion birds and 6.3–22.3 billion mammals annually. Un-owned cats, as opposed to owned pets, cause the majority of this mortality.”

The study’s findings suggest that “free-ranging cats… are likely the single greatest source of anthropogenic mortality for US birds and mammals.”

Salem nature advocate Aileen Kaye is alarmed by the damage done to wildlife by feral cats and the support they receive from the public.  She cites the disproportionately large donations Oregonians give to support feral cats and TNR efforts, as opposed to contributions to other environmental causes, as revealed by the 2013 Willamette Week Give Guide.

“These people are short – sighted,” Kaye says, “and they do not understand the ecosystem.”