May 28, 2011

Study Reveals Vast Range Of Outdoor Cats

The results of a two-year study released on Friday offers the first glimpse of the daily lives of feral and free-roaming house cats, capturing the roaming behavior of 42 owned and un-owned adult cats living in Illinois.

"There's no (other) data set like this for cats," said Jeff Horn, lead author of the study and a former graduate student at the University of Illinois, who led the study for his master's thesis with colleagues from his department and the Prairie Research Institute.

"Without these sensors, it would require a field team of 10 to 12 people to collect that data," Horn adds.

The researchers used radio telemetry and complex activity-tracking devices to monitor the cats over an area of 2,544 hectares (6,286 acres). 

Unsurprisingly, in most cases the un-owned cats covered larger territories and were more active than the domesticated cats.  However, the size of some of the feral cats' home ranges surprised the scientists.

One of the feral cats, a mixed-breed male, covered a range of 547 hectares (1,351 acres) in both urban and rural areas "“ the largest of any of the cats observed in the study. 

"That particular male cat was not getting food from humans, to my knowledge, but somehow it survived out there amidst coyotes and foxes," said Horn.

"It crossed every street in the area where it was trapped. (It navigated) stoplights, parking lots. We found it denning under a softball field during a game."

The cats that had owners traveled dramatically smaller areas, and tended to stay close to home.  Indeed, the mean home range for pet cats observed in the study was less than two hectares (4.9 acres).

"Still, some of the cat owners were very surprised to learn that their cats were going that far," Horn said. "That's a lot of backyards."

The domesticated cats were, on average, either asleep or in low activity 97 percent of the time, spending just 3 percent of their time engaged in highly active pursuits, such as running or stalking prey, the researchers said.  By comparison, the un-owned cats were highly active 14 percent of the time.

"The un-owned cats have to find food to survive, and their activity is significantly greater than the owned cats throughout the day and throughout the year, especially in winter," Horn said.

"These un-owned cats have to search harder to find food to create the (body) heat that they need to survive."

The cats also differed in the types of territories they covered, with pet cats randomly wandering in different habitats, while un-owned cats exhibited seasonal habits.  

For instance, feral cats stayed closer to urban areas than expected during the winter, but spent significant time in grasslands, including a restored prairie, throughout the year.

Most of the cats in the study stayed within about 300 meters of human structures, said co-author Nohra Mateus-Pinilla, a wildlife veterinary epidemiologist at the Illinois Natural History Survey at Illinois.

"Even feral cats were always within range of a building," she added.

"That shows that even though they're feral, they still have a level of dependency on us," she said.

The overlap of feral and pet cat territories can create problems for the environment as well as the cats, the researchers said.

In a previous study, co-author Richard Warner followed the cats of several rural residences over many years.

"Two of the leading causes of cat deaths in that study were other cats and disease," Warner said.

"And both of these leading causes of death are sitting here waiting for these owned cats outdoors."

Cats also get diseases from wildlife or other cats, and can bring them home to infect owners and other pets, Mateus-Pinilla said.

"For example, Toxoplasma gondii, a parasite spread primarily by cats, may cause neurological, reproductive and even respiratory problems in humans, cats and wildlife, depending on the species affected," she said, adding that rabies, cat scratch fever, feline leukemia and feline immunodeficiency virus are also of concern to pet owners whose cats encounter other cats outdoors.

Vaccination of pet cats can lessen, but not eliminate, the threat of disease transmission, she said.

Although pet cats have comparatively small ranges, and are active only in short bursts, their impact on wildlife in close vicinity of their homes is likely more severe than that of a feral cat that wanders over large areas, Warner said.

Unlike other feline predators, domestic cats are an invasive species that have a disproportionate effect on wildlife "“ either through predation or disease, Horn said.

Wild animals that have adapted to ecosystems that are already fragmented are even more endangered because domestic cats are disrupting the ecosystem by hunting, competing with native predators or spreading disease, he explained.


Image Caption: The cats were fitted with radio collars and tracked over two years. Some of the collars also had devices that continuously monitored the cats' every move. This un-owned cat was one of those tracked. Credit: Illinois Natural History Survey


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