More Studies Document Dramatic Impacts to Birds from Outdoor Cats

Reprinted from the American Bird Conservancy Bird Conservation Updates and Alerts

A new study from British scientists published in the Journal of Applied Ecology (January 30, 2013) has documented for the first time, significant new impacts to birds from outdoor cats, reporting that even brief appearances of cats near avian nest sites leads to at least a doubling in lethal nest predation of eggs and young birds by third-party animals, as well as behavioral changes in parent birds that lead to an approximately 33 percent reduction in the amount of food brought to nestlings following a predation threat.

The study was carried out by observing 47 blackbird nests in 2010 and 49 nests in 2011 in Sheffield, England, during the breeding season from March to August and compared nest dynamics following presentation of a taxidermist-prepared cat, a predatory grey squirrel, and a rabbit. The crucial finding is that the natural response of parenting birds to the appearance of predators – alarm calling and nest defense – dramatically affects rates of bird nest predation by third-party animals thusly alerted to the nest, as well as much lower feeding rates of young birds for prolonged periods following the threat of predation by cats.

A second new study by federal and university scientists has provided the first direct videographic evidence of depredation of the endangered Hawaiian Petrel by feral cats. The study affirms large amounts of earlier anecdotal evidence that feral cats are an important factor in population declines of the species and provides important additional information on the behavior of cats at petrel burrows. The study, which was prepared by scientists from the University of Hawaiʻi, National Park Service, and U.S. Geological Survey, involved the monitoring of 14 Hawaiian Petrel burrows with digital infrared video cameras that produced 819 videos and 89 still photographs during 2007 and 2008 at petrel nesting areas on Mauna Loa on Hawaiʻi Island. The study confirmed the presence of feral cats at eight burrows. See http://www.abcbirds.org/newsandreports/releases/130417a.html and
http://www.abcbirds.org/newsandreports/releases/130418a.html for more information.