The clapper rail, a secretive denizen of the salt marsh, is found nowhere else in the world except San Francisco Bay tidal marshes. One clapper rail, fitted with a radio telemetry device as part of the research study, was, itself, killed by a feral cat, and biologists continue to observe cats frequently stalking rails in area marshes. In four other marshes more distant from residential neighborhoods, however, the number of cats was lower. Elsewhere in the Bay area, California least terns facing cat and fox predation abandoned their nesting colony on the grounds of Oakland International Airport in the early 1990's. Farther south, predation problems continue at Salinas National Wildlife Refuge and at adjacent state parks in the Monterey area, where exclosure fencing has been built to protect western snowy plover nests.
Concerns exist in other states, too.
In Florida, marsh rabbits in Key West face predation from domestic cats, and several unique species of island mice and woodrats have been driven to near-extinction by cats introduced by people living on coastal barrier islands. A recent Wisconsin study put the annual toll to migratory birds from free-ranging domestic cats in the rural areas of that state at an estimated 39 million birds. This publication is not copyrighted and duplication is permitted and encouraged by the authors.