By Jeanne Moos
(CNN) - It turns out cats do a lot more than just sleep, eat and purr.
Ever wonder what cats do when they think we're not looking?
Now we know. They're jumping over fences, scrambling across roofs, hiding under cars, and growling at dogs.
University of Georgia researchers teamed up with National Geographic to put Critter Cams on 60 pet cats. The video was eye opening for the owner of Booker T.
"I knew Booker T's favorite place to go was down in the storm sewer. Now I know what storm sewer looks like," said his owner.
And when Booker T stopped for a drink, you could almost taste it.
Then there was the cat that stumbled on a tree stump full of Chex Mix to chew on.
But the most popular prey for cats in the study was lizards. Turns out, there was a lot of bird watching, but less bird killing. Birds accounted for only 12 percent of the creatures killed.
The study resulted in cat calls ranging from virtual killing machines to secret world of slaughter, though only 44 percent of cats did any hunting when left outside.
"They brought home an average of two prey items per week," said Professor Sonia M. Hernandez with the University of Georgia.
That probably doesn't count the cat that attacked an opossum that came too close to the cat's home.
Chief researcher Kerrie Anne Lord said most cats left their prey after they killed it.
"Rather than bring it home as a gift for the owners," said Lord.
It doesn't take a kittycam to know that cats turn up in weird places, like the ceiling of the University for Peace in Costa Rica.
But one of the most common places they hang out seems to be under cars. One of the cats gave the undercarriage of a truck a closer look than most mechanics would.
Perhaps the most emotionally devastating revelation from the study was four of the cats were found to be leading double lives, cheating on their owners.
Archie the tabby was caught on kittycam in a neighbor's house.
"Not just food but also love and affection and a place to sleep during the day," said Hernandez.
As for the owner, "I feel like one of these women on talk show. My husband has two wives. My cat has two families."