Free-Roaming Cats: A Conservation Crisis

Domestic cats (Felis catus) can provide excellent companionship and make wonderful pets. But when allowed to roam outdoors, this non-native, invasive species threatens the welfare of birds and other wildlife and endangers the integrity of the ecosystems into which domestic cats are introduced.


Domestic cats are recognized as a threat to global biodiversity. Cats have contributed to the extinction of 33 species across the world and continue to adversely impact a wide variety of species, including those that are threatened or endangered. The ecological dangers are so critical that the International Union for the Conservation of Nature (IUCN) now lists domestic cats as one of the world’s worst non-native invasive species.


In the U.S., free-roaming domestic cats kill an estimated 1.4-3.7 billion birds and 6.9-20.7 billion mammals. The sheer quantity of cat-caused mortality is staggering. For perspective, consider that 1.4 billion is equivalent to the entire human population of China, the most populous country in the world. As the number of cats continues to grow and owners continue to allow their pets to roam, harmful impacts will surely increase.

Strategic Conservation Framework

American Bird Conservancy’s Strategic Conservation Framework helps to focus our efforts on the issues most pertinent to birds. As an efficient and pervasive non-native predator, domestic cats fall into the eliminating threats category.

Birds Impacted

The following list of birds presents a brief introduction into the wide variety of bird species and conservation statuses impacted by domestic cats: Northern Cardinal, California Quail, Carolina Wren, Wood Thrush, Hawaiian Petrel, Eastern Bluebird, Ruby-throated Hummingbird, Piping Plover.