I get particularly distressed by cats that are allowed to roam - or cats that have been allowed to go wild (feral). They do not belong in our eco-system and the damage they do to our wildlife is extraordinary. I do make an exception for 'working' cats that are needed to keep rodents out of feed in agricultural situations. But those are only a tiny proportion of the implacable and efficient hunters that we have unleashed upon the landscape.
Now, a new study in which scientists from University of Georgia and the National Geographic Society put small video cameras on cats has prompted the American Bird Conservancy and the Wildlife Society to conclude that cats are responsible for even more wildlife deaths than was previously thought - more than 4 billion animals a year, of which about 500 million are birds.