For example, most young birds leave the nest before they can fly well. Whenever you see newly fledged baby robins on the ground taking short practice flights, you'll know they are easy prey for a cat. Do the Math Scientists estimate that cats kill hundreds of millions of birds and three times as many small mammals each year. Most of the birds are common species, such as the Northern Cardinal, American Robin, or Song Sparrow. But others, such as the California Least Tern or the Piping Plover, are rare or endangered.
ALL wild creatures suffer when captured by a cat.
By letting our cats outside, we are placing a higher value on the freedom of our pet than on the life of the cardinal, robin, baby rabbit, or chipmunk that she kills. Worldwide, cats may have been involved in the extinction of more bird species than any other cause except habitat destruction. Cats with bells on their collars can learn to stalk their prey silently. Even if they don't, wild birds do not necessarily associate the ringing of a bell with danger. Because different portions of a cat's brain control the urge to hunt and the urge to eat, even well fed cats may kill wildlife.