Here’s What Would Happen If All the Cats Died


Earlier this week, author Natalie Wolchover wrote an article for Live Science titled “What If All the Cats in the World Suddenly Died?

Groups like the American Bird Conservancy and all the people who’ve fallen for the bad science that has scapegoated cats as the number one killer of all the pretty little birdies might rejoice. Legions of cat lovers would certainly grieve the loss of their beloved companions. But amidst all the emotional response, only a few people have any idea of the dire consequences that could result from the disappearance of a predator that is, in fact, crucial to our environment.

Now, I’ll start off here by saying that I don’t make any claim to be a scientist, but I do remember my college biology classes. There’s also a part of my nerdy little heart that has a place for science and ecology that has caused me to do a lot of recreational reading on the subject.

Bird advocates often say that cats are foreign to our environment and therefore our poor feathered friends have no ability to deal with domestic cats. But the truth is, cats have been domesticated for thousands of years, so they are a part of the ecosystem and our ecosystem is designed to accommodate them.

You know what happens when a predator is instantly removed from an ecosystem? If other predators like weasels and foxes don’t fill the vacuum left by cats (and trust me, they probably would), a phenomenon called trophic cascade occurs. What that means is, if all the cats instantly died and no other animals took their place, rodent and bird populations would rise exponentially. This would lead to the a vastly increased demand on the available food supply. Seeds and nuts would be consumed to such an extent that grass, trees and wildflowers would stop growing (no seeds = no new plants), and our own vegetable gardens and grain storage facilities would be pillaged, too.

The burgeoning population of rats and birds, crammed together in close quarters due to humans’ destruction of their wild habitat, would inevitably lead to outbreaks of disease, which could rapidly become epidemics. Many of these diseases are zoonotic — that is, they infect people, too. Fleas carried on rats (whose population spiraled out of control after the mass execution of cats due to superstition about their association with Satan) caused the vast outbreak of the bubonic plague in the Middle Ages, for example. Although we’ve got antibiotics to treat the plague now, we’re not so lucky with rat-borne diseases like hantavirus or bird-borne diseases like avian flu. Antibiotics don’t kill viruses.

Sure, this may all be hyperbole, but there have been plenty of studies, written by respectable scientists, on the important role of domestic cats in the survival of our ecosystem. We also have examples of similar phenomena happening with high-level predators. When wolves were eliminated from Yellowstone National Park in the late 19th century, for example, the elk population exploded. Elk feed on aspen trees and grass, and the grazers’ vastly increasing numbers more or less destroyed the vegetation in the park. Even today, 15 years after wolves were reintroduced to the park, the aspen population isn’t recovering: it may just be that the extirpation of the gray wolf and the resulting elk population boom have forever altered the environment there.

Of course, some people will say that cats are nowhere near as important as wolves because they only feed on small animals. But if the bird advocates think cats are such a huge danger to the avian population, they must, somewhere in a rational corner of their minds, be able to imagine that a wholesale destruction of cats could result in a similar disaster.

You can’t eliminate any one animal from the environment without causing a cascade of unintended consequences that could have pretty horrific outcomes. Life is a web, and the disturbance or destruction of any one strand can send the whole thing into collapse.

Yes, cats are that important. For that matter, so are ants, gnats, mosquitos, venomous snakes, and everything else.

(If you want to see a full list of diseases transmitted by rodents and diseases transmitted by birds, knock yourself out! Then thank your cat for his or her role in controlling prey animal populations.)

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