The conflict between cats and wildlife

By Janet Carroll | Apr 03, 2013

I have some unwanted visitors to my property: my neighbors’ cats and stray cats. While I find cats sweet and friendly creatures for the most part, they do a lot of killing of local wildlife; the animals for which I have created wildlife habitat.

I recently read an article in Nature Communications entitled, “The impact of free-ranging domestic cats on wildlife of the United States.” ( The article was the result of a study done by research scientists at the Smithsonian Conservation Biology Institute.

The study looked at predation of birds and mammals by cats, one of a number of studies trying to quantify human caused problems that have resulted in a major decline of bird and mammal populations in the United States.

Astonishingly, the study found that cats kill between 1.4 billion and 3.7 birds every year and 6.9 to 20.7 billion mammals.

In my yard, the birds killed by cats include thrushes, sparrows, juncos, hummingbirds, wrens and kinglets. The mammals killed by cats include moles, shrews, deer mice, chipmunks and Norway rats.

How do I know this? My neighbor reports on the dead birds and animals brought into her home by her cats.

The study looked at owned cats that are allowed outside and un-owned cats – stray cats and feral cats living in colonies. Thirty to 80 million colonies of cats were identified throughout the country during the study.

In Mukilteo, most of the colony cats live in our ravines or near water. I don’t know how many colonies there are, but I encountered one in Old Town. A friend and I were walking in the area and noticed 11 cats spaced around the end of a street, staring at us.

Neighbors told us that there were 50 cats living in the ravine there. Some of the cats are being fed by cat-loving landowners, and a volunteer group in the city that catches feral cats has them spayed or neutered, and then releases the adults back to their colony site.

Adult feral cats are very hard to tame so they are not suitable as pets, but the group often finds homes for the kittens of the feral cats.

There are many cat lovers who will defend with their last breath the necessity of letting their cats roam outside and justify this in any number of ways, one of which is that their cats kill rats.

Unfortunately, there is no way to train a cat to capture only non-native (Norway) rats, which in the study were found to be a small portion of the mammals killed by cats.

The numbers of birds in our city and elsewhere are declining, and our native mammals are part of our ecosystem and need to be there.

I adore cats; my favorite of course is my cat, Jules. I come from a family of cat lovers whose cats are Maggie Sue, Scooter, BoBo, Gabby and Joey.

I know firsthand how hard it is to convince people to keep their cats inside; Gabby and Joey are indoor/outdoor cats. Convincing kind, cat lovers not to release the feral cats back to the wild is a tough one as well.

“Cats are natural predators of not just birds but also mammals – killing is what they are meant to do and it’s not their fault,” said Pete Marra, one of the study scientists. “Removing both pet and feral cats from outdoor environments is a simple solution to a major problem impacting our native wildlife.” (

How do we do that? Here are two proposals:

• For owned cats – Do not give or sell cats to people who will not keep them inside. Some pet rescue centers already do this.

• For feral cats – Do not release spayed and neutered cats back to their colony site. Use funding from organizations like the Audubon Society, which is one of many wildlife organizations concerned about this problem, to provide a place for feral cats where they can live out their lives well fed on cat food, not wildlife.

These solutions may not bring an end to cat predation on wildlife, but could at least put a dent in the problem.

Janet Carroll is a member of the Mukilteo Wildlife Habitat Project. The group is committed to wildlife by creating and enhancing wildlife habitat in Mukilteo and connecting residents with nature. For more information, go to, email or phone 425-514-5979.

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