Ever wondered where your cat slinks off to when it goes outside?

Cat Tracker, a new crowdsourced mapping project, encourages owners to put GPS collars on domestic cats to monitor their movements and activities around—and sometimes well beyond—the 'hood. (Watch a video about the secret lives of cats.)

The resulting data could help conservationists save wildlife that the cats prey on, as well as reveal new insights into cat behavior, experts say.

Our pet cats are a pretty lazy bunch, sleeping or at least lying around well over 90 percent of the time. But still, when that screen door shuts behind them, our felines are prone to roam. (Also see "What Do Cats Think About Us? You May Be Surprised.")

One thing that makes the Cat Tracker project different from other animal-tracking efforts is that anyone in the U.S.—and now in New Zealand and Australia—can participate. A cat owner must simply buy or borrow a GPS unit and make a harness to hold it on the cat, using a method explained on the Cat Tracker website.

After seven days, owners download the tracking data (also explained online), and boom, the cat's movements are transformed into a starburst of lines on a satellite map.

In the Footsteps of Felines

The data may help scientists figure out what impact cats are having on their environments.

In the U.S., for instance, "ecologists are concerned about where cats go, because they have a reputation for killing lots of native birds and mammals," said Roland Kays of the Biodiversity and Earth Observation Lab at North Carolina State University in Raleigh, one of the project leaders.

"There are so many cats in the country [some 95 million are pets, plus millions more are feral] that they could be doing damage to our wild animal populations," he said. "But it really depends on if they are hunting in urban areas or moving out into our nature preserves." (See "Vasectomies Could Cut Feral Cat Population.")

Anthropologist Barbara King of the College of William & Mary in Williamsburg, Virginia, an expert on feline behavior who isn't involved in the project, said Cat Tracker is a great way to solve this important mystery, since more hard data on cat predation is "sorely needed."

Not to mention, as King said, "it would just be fascinating to learn how far they go and where!"

In addition, following in feline footsteps could elucidate how their "outdoor diet" relates to disease and parasites, noted NC State veterinarian Suzanne Kennedy-Stoskopf, who's part of the project.

Kennedy-Stoskopf has a list of questions she hopes Cat Tracker will answer: "Do presumably well-fed cats kill and eat wildlife routinely? Is it just a subset of cats that do this? Is there any relation between the quality of indoor diets and outdoor prey behavior?"

And finally, "Do cats that ingest wild prey have greater parasite burden in their digestive tracts, and do any of these parasites pose a risk to their owners?"

Curious Cat Owners

Meanwhile, some of us are simply curious to know if our cats are cheating on us with other cat-loving households. (Also see "How Cats and People Grew to Love Each Other.")

After years living in another house, "the first cat we tested, belonging to Rob Dunn [of Your Wild Life], went back to its old house," just over 0.75 mile (1.2 kilometers) away from its current home, Kays said.

"That was a surprise"—not many studies have assessed how well cats can navigate and remember past routes, he said. But anecdotal evidence suggests they are better at it than we think.

A smaller cat-tracking project in central Illinois in 2011 revealed the travels of 42 adult cats ranging over more than 6,000 acres (2,400 hectares) of land. Unowned cats proved to be the most active and had the highest mileage. (See National Geographic readers' pictures of cats.)

One feral male had a home range of more than 1,300 acres (520 hectares), almost double the size of New York's Central Park. It wandered through a combination of urban and rural sites that exposed it to a variety of dangers, from busy streets and parking lots to coyotes and foxes.

So far Cat Tracker's subjects haven't covered nearly as much ground—the longest trip so far belonged to Natasha, at 0.8 mile (1.3 kilometers)—but its still early in the project, with hundreds of mystery movements yet to be mapped.

"I expect we'll get lots of surprises," Kays said.

Kitties, take your marks...