Cats Indoors Program

The domestic cat is a non-native and invasive species. An estimated 600 million cats live worldwide, with approximately 160 million in the US. The domestic cat reaches sexual maturity at six months. Reproduction can occur throughout the year, and one female can produce up to 12 offspring annually.

Cats are highly efficient, instinctive predators; even well-fed, they continue to hunt and kill wildlife. Worldwide they are responsible for the extinction of numerous mammals, reptiles and at least 33 bird species.

A January 2013 study conducted for the Smithsonian Conservation Biology Institute and the US Fish and Wildlife Service estimates that in the US each year outdoor cats kill 1.4-3.7 billion birds and 6.9-20.7 billion mammals, reptiles and amphibians. Studies show that as cat abundance increases, native bird diversity plummets.


  1. Keep your cat indoors and encourage others to do the same.
  2. If you are unwilling to keep your cat indoors, do not attract birds.
  3. Do not rely on bells or declawing to prevent successful hunting; these measures are not effective.
  4. Spay or neuter your cat and don’t feed other outdoor cats.
  5. Never abandon unwanted cats.
  6. Download Mt. Diablo Audubon Society’s conservation flyer and share it with your friends!