Cats are found to be responsible for the deaths of about 1.4 to 3.7 billion birds and 6.9-20.7 billion mammals annually, claims study.
The scientists said that stray and feral cats were the worst offenders, the BBC reported.
However, they added that pet cats also played a role and that owners should do more to reduce their impact.
The authors concluded that more animals were dying because of cats in the US than in road accidents, collisions with buildings or poisonings.
Researchers from the Smithsonian Conservation Biology Institute (SCBI) and the US Fish and Wildlife Service carried out a review of studies which had previously looked at the cat's predatory prowess.
Their analysis revealed that their killing were much higher than previous studies had suggested: they found that the cat had killed more than four times as many birds as has been previously estimated.
Birds native to the US, like American Robin, were most at risk, and mice, shrews, voles, squirrels and rabbits were the mammals most likely to be killed.
The team said that "un-owned" cats, that they classified as strays, feral cats and farm cats, were killing about three times as many animals as pet cats.
The study has been published in Nature Communications.