I am fortunate to have a job that allows me to travels to wild and scenic places all over the world. I get to see, photograph and write about some amazing wild places while spending a lot of time outdoors. However when I am on location, I too often see something that is a bit concerning–domestic cats roaming free. As a naturalist and biologist I have to say that free roaming domestic cats are a problem for wildlife. I don’t believe anyone would dispute this. In addition let me first say that I owned cats for over 20 years and I am a big fan of domestic cats. I want to address the free roaming cats. My cats were indoor cats.
Let’s review what we know about domestic cats. They originated from wild cats in Europe and Africa and were domesticated many thousands of years ago. The Greeks and Romans helped to spread cats around the world. Presently domestic cats are found in all parts of the world where ever people exist.
Today the number of domestic cats in the world stands around 600 million. In the US the number of domestic cats is estimated at 120 to 150 million. Approximately 30 percent of all households have a cat. These are just the cats that people claim to own and doesn’t include feral cats. If you break this down roughly state by state there is an estimated 2.5 to 3 million cats per state. Of course the states are not equal in size or population so this means some states have more and others have less. For example it is estimated that states such as Wisconsin and Minnesota have about 4 million cats per state.
So how do these cats effect wildlife. Studies of the feeding habits of free roaming domestic cats over a 50 year period shows that small mammals such as mice, voles and shrews make up about 70 percent of their diet. Small birds make up about 20 percent of their diet. However this may only reflect the locally available food source and may be different in your area.
Some estimates are that some individual free roaming cats can kill up to 1000 wild animals and birds per year. More typically individual cats kill hundreds of birds and small mammals each year. Rural cats kill more than urban or suburban cats presumably they have access to more critters to kill. Even if one cat kills just one bird per year the number of birds taken by these cats is still in the millions.
In one study by Stanley A. Temple from the University of Wisconsin-Madison shows that free roaming domestic cats in Wisconsin may be killing between 20 to 40 million birds each year in Wisconsin alone. Estimates in this study show that on average, about 30 million birds are killed in each state each year. This includes all species of song birds and also game birds.
National wide cats kill over a billion small mammals and hundreds of millions of birds each year. The problem with this is, the domestic cats are out-competing the native predators. These cats may also be transmitting diseases to wild animals. For example it has been shown that domestic cats have spread feline leukemia virus to Cougars (also called Mountain Lions). Domestic cats can also carry and transmit diseases to humans such as rabies and toxoplasmosis.
In general, free roaming domestic cats is a widespread problem that affects the densities and diversity of wild animals and birds, some of which may be rare or endangered. They out-compete our native predators reducing the available food sources. They are also vectors for disease and yet may believe that it is ok to let their cats roam free. If you are a cat owner please consider the consequences of your actions and think about your decision to let your cat roam free. Until next time…
Stan Tekiela is an author / naturalist and wildlife photographer who travels the US to study and photograph wildlife. He can be followed on Facebook.com and Twitter.com. He can be contacted via his web page at www.naturesmart.com