Domestic cats might be determined hunters, but they stick mostly to residential areas instead of venturing into parks and protected areas where coyotes roam. That's the key finding from a North Carolina State University analysis of more than 2,100 sites - the first large-scale study of free-ranging cats in the U.S. published in the Journal of Mammalogy.
Why is it important to know where 74 million pet cats spend their time away from home?
"Domestic cats are estimated to kill billions of birds and small mammals each year," says lead author Roland Kays, a zoologist with NC State's College of Natural Resources and the N.C. Museum of Natural Sciences. "Knowing where they hunt helps assess the risk to wildlife."
Kays and his colleagues used camera trap data collected by hundreds of students and citizen scientists in six Eastern states. They analyzed millions of images data from motion-sensitive cameras located in 32 protected sites and the urban neighborhoods of Raleigh, North Carolina.
Cats were concentrated in residential areas and small urban forests, such as those along Raleigh's greenway trails.
"We detected cats 300 times more often in residential yards, where coyotes are rare, than in parks," Kays says.
The more coyotes in an area, the less likely cats were to venture nearby. The one area where both cats and coyotes overlapped was small urban woodlots.
"Most parks had no cats at all," Kays says. "Our cameras photographed a single cat at some parks, but we only found evidence for more than one cat in two of the 32 parks we surveyed."
Another interesting finding: Cats that did venture into nature preserves kept the same nocturnal schedule as coyotes, while those in residential areas were diurnal.
The study is part of the eMammal project, which enables citizen scientists to collaborate with researchers at the Smithsonian Institution and NC State University to document animal activity.
Co-author Robert Costello is with the Smithsonian National Museum of Natural History. Tavis Forrester, Megan C. Baker and William McShea are with the Smithsonian Conservation Biology Institute. Arielle W. Parsons works with the North Carolina Museum of Natural Sciences. Elizabeth L. Kalies and Joshua J. Millspaugh are with the University of Missouri. George Hess is with NC State University.
Note: An abstract of the paper follows.
"Cats are rare where coyotes roam"
Authors: Roland Kays, Robert Costello, Tavis Forrester, Megan C. Baker, Arielle W. Parsons, Elizabeth L. Kalies, George Hess, Joshua J. Millspaugh, William McShea
For publication: June 30, 2015, in Journal of Mammology
Abstract: Domestic cats (Felis catus) have caused the extinction of many island species and are thought to kill many billions of birds and mammals in the continental United States each year. However, the spatial distribution and abundance of cats, and their risk to our protected areas remains unknown. We worked with citizen scientists to survey the mammals at 2,117 sites in 32 protected areas and one urban area across six states in the Eastern USA using camera traps. We found that most protected areas had high levels of coyote (Canis latrans) activity, but few or no domestic cats. The relative abundance of domestic cats in residential yards, where coyotes were rare, was 300 times higher than in the protected areas. Our spatial models of cat distribution show the amount of coyote activity and housing density are the best predictors of cat activity, and that coyotes and cats overlap the most in small urban forests. Coyotes were nocturnal at all sites, while cats were nocturnal in protected areas, but significantly more diurnal in urban sites. We suggest that the ecological impact of free-ranging cats in the region is concentrated in urban areas or other sites, such as islands, with few coyotes. Our study also shows the value of citizen science for conducting broad-scale mammal surveys using photo-vouchered locations that ensure high data quality.