(WTVR) – There could be a silent killer lurking in your home…your cat.

From November 2010 to October 2011, researchers strapped lightweight video cameras onto 60 house cats in Athens, Ga., to find out exactly what domesticated kitties do and where they go when their owners let them out to roam.

Two thousand hours of footage later, they had their answer.

The research focused on the risk to native wildlife species of letting domesticated cats play outside, and the risk to the cat itself. In conclusion, researchers found that it is better for wildlife and for cats if they remain indoors as much as possible.

Researchers at the University of Georgia say that 44% of roaming cats hunt wildlife and on average make two kills a week.

While two kills a week might not seem like a lot, it really adds up considering people in the U.S. own an estimated 86-million cats, according to the American Pet Products Association.

The American Bird Conservancy told U-S-A Today those predator cats are wiping out the bird population.

The Conservancy’s president says one in three American bird species is in decline and he blames felines.