A chart showing estimated numbers of birds killed annually by each of several different causes. Data from various sources.
Domestic and Feral Cats – may kill 500 million birds per year or more. More information can be found at The American Bird Conservancy. Predators, of course, account for the vast majority of bird deaths each year, and most of this predation is natural.
Domestic cats are not natural predators, but kill many birds. It is worth noting that house cats have been blamed for the extinction of two species of small mammals in the southeastern United States, and feral cats continue to be a huge problem where they have been introduced on many oceanic islands.