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T50 U S G S science for a changing world Feral Cats: Too Long a Threat to Hawaiian Wildlife This feral cat was photographed by a remote camera in Hawail Volca- noes National Park (see page 3). _ of endemic forest birds were either greatly reduced in number or became extinct between 1870 and 1930. One of the earli- est naturalists to implicate feral cats as a causal factor in these losses was R.C.L. Perkins, who wrote in 1903: r, On Lanai, in walking up a single ravine, I counted the re- mains of no less than twenty-two native birds killed by cats, and these must all have been destroyed within two days, as previously the whole gulch had been washed out by a heavy flood. Two cats were actually shot on this occasion as they were devouring their prey, and several others seen, but, owing to the fact that they are extremely shy and mostly nocturnal in habits, few people who have not lived much in the woods have any idea of their numbers. In Hawaii today, cats range from relatively high densi- Background ties near sea level where abandoned pets are frequently fed by Domestic cats (Felis catus) were first brought to Hawaii well-meaning animal-lovers, to sparse isolated populations in aboard sailing ships of European explorers and colonists. The remote rain forests and even alpine areas on the islands of Maui job of these predators was to control mice and rats on the ships and Hawaii. Cats kill songbirds, which nest, feed, and roost in during the long voyages. As in other places, cats were taken in trees, and ground nesting birds, such as quail and other intro- and adopted by the families of Hawaii and soon became house- duced game birds. Native sea birds and other species that nest hold pets known as popoki. But cats have always been very well on the ground or in burrows are particularly vulnerable to preda- equipped to live and hunt on their own. On tropical archipelagos tion by cats. For example, endangered 'ua'u (Hawaiian Petrel; like the Hawaiian Islands where no other predatory mammals of Pterodroma sandwichensis) are particularly vulnerable because comparable size existed, abundant and naive prey were particu- they raise their single chicks in lava crevices and nestlings can- lady easy game, and cats soon thrived in the wild. not fly for more than 15 weeks after hatching. Adult 'ua `u are Although the details of when cats first came to live in the also often killed by cats, causing serious population declines wild remain little known, adventurers, writers, and naturalists because it takes each bird five to six years to reach of the day recorded some important observations, Feral cats were observed in remote wilderness around Kilauea volcano on Hawaii Island as early as 1840 by explorer William Brack- enridge. Mark Twain was so impressed by the great abundance of cats when he visited Honolulu in 1866 that he reported his observations in the Sacramento Union newspaper, which were later reprinted in his book Roughing it. I saw... tame cats, wild cats, singed cats, individual cats, groups of cats, platoons of cats, companies ofcats, regiments of cats, armies of cats, multitudes of cats, millions ofcats... Cats Prey on Native Birds in a Variety of Habitats Cats were also common in remote and isolated communities, Left.'Ua'u are rare and endangered long-lived as noted by the famous traveler, Isabella Bird, during her visit to seabirds thatfeed on fish and squid offshore but nest in Waimanu Valley on Hawaii Island in 1873. By that time, a dis- lava crevices at high elevation on volcanoes. (Photo by W. 8anko) Right, turbing but little known phenomenon was beginning to happen This adult'ua'u was killed by a cat high on the slopes of Mauna Loa in to the unique birds of Hawaii. At least 30 species or subspecies Hawaii Volcanoes National Park. (Photo by F. R. Warshauer, USGS) U.S. aeparoneat of the Interior ®rrinred an recycfee oeaer USGSF7p0SIM Jannrv2xs U.S. Geological Surrey