Back in 2013, a scientific manuscript was published in the academic journal Nature Communications implying that cats are responsible for killing multiple bird populations in the United States and around the world including birds belonging to endangered species. In the US, the study says, cats kill almost 4 billion native birds a year, an amount larger than buildings, towers, windows, poison, and cars. However, the cats they point to as the primary culprits are unowned cats, not necessarily felines that are owned.

Live Science interviewed Dr. Pete Marra who is an animal researcher at the Smithsonian Conservation Biology Institute and one of the scientists that participated in the study:

The major scourges for wildlife were not those free-ranging, owned-cats, but instead feral and un-owned cats that survive on the streets. Each of those kitties – and the team estimates between 30 million and 80 million of them live in the United States – kills between 23 and 46 birds a year, and between 129 and 338 small mammals, Marra said.

And, it seems, the small rodents taken by felines aren’t Norway rats or apartment vermin, but native rodent species such as meadow voles and chipmunks, he added.

The issue is that unowned cats are primarily responsible for killing bird species native to their areas. Marra suggests one solution would be to keep cats indoors so they do not disturb local ecosystems. Because of similar reasons outlined in a study conducted by a New Zealand environmentalist group, an environmentalist there proposed banning cat ownership. Thankfully, his proposal went nowhere.

While it makes sense for cats not to be released into the wild, cats not only add great value to people’s lives for companionship but also are a check on the amount of vermin among ecosystems like pigeons, rats and insects as well. It is studies like this that are the basis of ridiculous policy proposals, like the ban on cats the New Zealand environmentalist proposed. The above manuscript can be justified to not only ban cats but it would be used as an attack on the human ego because of the companionship cats provide for humans, along with the benefits of them being rodent and vermin exterminators.