A new study of house cats allowed to roam outdoors finds that nearly one-third succeeded in capturing and killing animals. The cats, which wore special video cameras around their necks that recorded their outdoor activities, killed an average of 2.1 animals every week they were outside, but brought less than one of every four of their kills home. Of particular interest, bird kills constituted about 13 percent of the total wildlife kills. Based on these results, American Bird Conservancy and The Wildlife Society estimate that house cats kill far more than the previous estimate of a billion birds and other animals each year.
The study was carried out by scientists from the University of Georgia and the National Geographic Society's Crittercam program.
“The results were certainly surprising, if not startling,” said Kerrie Anne Loyd of the University of Georgia, who was the lead author of the study. “In Athens-Clarke County, we found that about 30 percent of the sampled cats were successful in capturing and killing prey, and that those cats averaged about one kill for every 17 hours outdoors or 2.1 kills per week. It was also surprising to learn that cats only brought 23 percent of their kills back to a residence. We found that house cats will kill a wide variety of animals, including: lizards, voles, chipmunks, birds, frogs, and small snakes.”
Ms. Loyd and her colleagues attached small video cameras (dubbed Crittercams or KittyCams) to 60 outdoor house cats in the city of Athens, Ga., and recorded their outdoor activities during all four seasons. Ms. Loyd said the cats were outside for an average of 5-6 hours every day.
“If we extrapolate the results of this study across the country and include feral cats, we find that cats are likely killing more than four billion animals per year, including at least 500 million birds. Cat predation is one of the reasons why one in three American bird species are in decline,” said Dr. George Fenwick, president of American Bird Conservancy, the only organization exclusively conserving birds throughout the Americas.
“I think it will be impossible to deny the ongoing slaughter of wildlife by outdoor cats given the videotape documentation and the scientific credibility that this study brings,” said Michael Hutchins, executive director/CEO of The Wildlife Society, the leading organization for wildlife professionals in the United States. “There is a huge environmental price that we are paying every single day that we turn our backs on our native wildlife in favor of protecting non-native predatory cats at all cost while ignoring the inconvenient truth about the mortality they inflict.”
Volunteer cat owners were recruited through advertisements in local newspapers, and all selected cats were given a free health screening. Each cat owner downloaded the footage from the camera at the end of each recording day.
The new study does not include the animals killed by feral cats that have no owners. A University of Nebraska study released last year found that feral cats were responsible for the extinction of 33 species of birds worldwide, that even well fed cats in so-called “managed” cat colonies will kill, that feral cats prey more on native wildlife than on other invasive creatures, and that most feral cats (between 62 and 80 percent) tested positive for toxoplasmosis (a disease with serious implications for pregnant women and people with weakened immune systems).
This study was collaboration between Kerrie Anne Loyd and Dr. Sonia Hernandez from the University of Georgia, and Greg Marshall, Kyler Abernathy, and Barrett Foster of National Geographic’s Remote Imaging Department and was funded in part by the Kenneth Scott Charitable Foundation. For further information, please contact either kloyd@uga.edu or shernz@uga.edu.
View video and photos from the KittyCam at the University of Georgia's website.