A new book has labelled cats as unrelenting killers and an invasive species that is contributing to a sixth mass extinction that could affect the whole planet.
Cat Wars: The Devastating Consequences of a Cuddly Killer was co- written by Peter P. Marra, director of the Smithsonian Migratory Bird Center at the National Zoo.
"Inside, cats make excellent pets; loose on the landscape, they are - by no fault of their own - unrelenting killers and cauldrons of disease," he says.
The book traces the historical and cultural ties between humans and cats from early domestication to the current boom in pet ownership.
Mounting scientific evidence confirms, he says, that in the United States alone, free-ranging cats are killing birds and other animals by the billions.
“The densities of these cats is nothing like natural predator densities, song birds here for example experience all kinds of predation not just from a bob cat which would be the native species that was here at one time but racoons and squirrels and hawks - there’s a whole suite of predators.
“The problem is the domestic cat, those owned individuals that are allowed to go outside as well as un-owned individuals, are in extremely high densities.”
He says analysis from three years ago found cats kill between 1.3 and 4 billion birds per year and up to 15 billion mammals in the US.
“We can’t just be concerned about species when they’re threatened we really need to be concerned about them once they’re common.”
Equally alarming, he says, are the little-known public health consequences of rabies and parasitic toxoplasma passing from cats to humans at rising rates.