Free-ranging domestic cats in the United States are estimated to kill between 1.3 billion and 4.0 billion birds annually, with a median estimate of about 2.4 billion birds per year. The majority of this predation-approximately 69%-is caused by un-owned cats, such as feral, stray, and barn cats, which tend to have higher predation rates than owned cats allowed outdoors

. This large-scale estimate is based on systematic scientific reviews and data-driven analyses, considering factors such as the number of cats, their hunting behavior, and outdoor access. It highlights that cats are likely the single greatest source of human-related bird mortality in the U.S., surpassing other anthropogenic causes

. In summary:

• Estimated bird kills by free-ranging domestic cats annually in the U.S.: 1.3 to 4.0 billion birds
• Median estimate: about 2.4 billion birds
• Majority of kills caused by un-owned (feral/stray) cats (~69%)
• Cats are a leading anthropogenic threat to bird populations