This is Scientific American's 60-second Science, I'm Jason Goldman.Domestic cats that live or go outside kill lots of wild animals.Recent studies find that outdoor cats in North America take out between 10 and 30 billion birds and mammals each year.Still, it hasn't been clear what kind of an impact the world's 600 million pet cats have on wildlife populations―and whether that impact poses a threat to biodiversity conservation."Anyone who has a cat sees their cats bring animals home. And the question is, 'Well, does it matter?'And especially, we wanted to know, 'Where are the cats actually hunting?Are they hunting in their backyards? Or are they going out into the nature preserves?'"North Carolina State University zoologist Roland Kays.Together with colleagues in the U.K., Australia and New Zealand, Kays distributed small GPS trackers to citizen-scientist cat owners.They attached the trackers to their cats' collars.In all, more than 900 pet cats were tracked this way, all of which were routinely allowed to roam freely outside.Some cats were true explorers.One British cat called Max walked almost two kilometers back and forth along a road between two neighboring villages―twice!But the majority were homebodies, rarely straying more than 100 meters from home.In other words, they used their own backyards, plus those of a few neighbors, as their hunting grounds.
