Cat vs Rat

🌟 Editor's Note

This is somewhat based on a Bluesky thread that I put together, but that I want to expand upon. Because every time I post something about this, people come out of the woodwork applying their own vibes to scientific research.

Cats are killers. They pounce on mice, voles, sparrows, starlings, lizards. Anything that is nice and small and moves quickly is fair game. This is why people are very, very concerned about cat populations on islands, or near populations of endangered seabirds.

This is also why so many people have thought, hey, if we’ve got a rat problem, maybe what we need are CATS! Many cities have blue collar cat programs, where cats a little too stand-offish for the housecat lifestyle get placed around businesses, or on farms, to deal with the rats in the area.

I’ve seen many cats in this group. And in those areas where I see those cats, I also see a lot of rats. Because while housecats kill mice with abandon, a good RATTER? That’s hard to find.

The Hunting Hype

Cats are obligate carnivores, as in they only eat meat. They are live prey specialists, meaning they are especially interested if the prey is raw and wriggling. And they are also very broad in their tastes. If it moves, they’ll eat it.

This talent plays into the story of how cats became our companions in the first place. The idea is that we began to store food, especially grains. Those grains attracted mice and rats. Those rodents attracted cats. The cats hung out nearby and became attached to our lifestyle, if not to us. There’s even recent evidence from China backing up that idea with a different cat species: The leopard cat, whose association with humans ended up failing when the political system lost stability.

Humans have also talked and written explicitly about using cats for best control. Cats were on ships to control the rats, for example, or brought into homes to relieve a pest problem.

But were most cats actually hunting and eating those rats? It’s possible that while some were, many weren’t. When cats have a choice, a lot of them just avoid the whole rat issue. In a 2018 study of cat and rat colonies in NYC, Michael Parsons and his colleagues found that cats were not generally hunting rats. By and large, when cats lived near rat colonies, the two neatly avoided each other.

Another 2015 study looked at the prey preferences of about 26 cats, and found that cats had preferred preys and foods (I can tell you right now that one of my cats loves a blue-tailed skink, and pretty much nothing else). Of those, four cats out of 26 (15 percent) specialized in rats.

The most recent study is out of Chicago, where the scientists took blood samples from 57 stray cats, looking for rat poison in their blood. They were interested in terms of whether rat poison was negatively affecting cats (we know that it is negatively affecting birds of prey, which eat rats in large numbers in urban environments). At this point, almost every rat in an urban environment will have at least some rat poison in their blood, and it doesn’t exit the system, so to find rat poison in their blood is to assume the animals are eating rats.

That study found that four out of the 57 cats tests had evidence of rat poison, suggesting that only seven percent of stray cats were pouncing on rats. This is good in that the cats aren’t being hurt by rat poison.

But for the rat population? Well, it looks like cats aren’t going to solve that problem.

At first, this might be hard to process. If cats hunt small moving things, rats must qualify!

But I think there’s something of a misconception of how big cats are, how big rats are, and what it takes for a cat to fight a rat and win. Because, in my personal experience educating many, many people about mice, rats, and other animals people hate…wow no one knows how big a rat or a mouse is.

So let’s do some math. Consider a stray cat. She’s a good huntress, keeps it together, let’s put her at 9 lbs.

The average mouse comes in at a humble 1 ounce. A tiny little guy, easy prey, go get it girl. The average rat? Nearly a pound, maybe a little more. One ninth the size of the cat. In human terms this is roughly a full grown human man against a healthy beagle.

Now fight it (don’t really fight it). Yes, the person (or cat) could beat the beagle (or rat). But not, probably, without a bruise or bite or two. Rats have teeth that can bite through concrete.

To a human, with access to bandaids and rabies shots and dinner, this might be fine. A cat has different calculus. They have to walk away from that fight, and hunt again tomorrow. Why attack the rat when there are mice and sparrows and voles and lizards aplenty?

#notallkitties

Every time I post or write about whether cats as a species hunt rats, someone replies with “well I KNOW A CAT THAT” or “MY OLD CAT…”

And I believe you! I also personally know a cat who is such a menace that full grown German Shepherds drag their owners to the other side of the street out of sheer terror. I’ve never seen her take down a rat (or even a squirrel which we have loads of), but it would certainly not shock me. As these studies note, SOME cats will indeed specialize in rats. In the Chicago study it was four out of 57 (as measured by rat poison in the blood), in other studies I saw four out of 26. Most studies looking at “prey preference” unfortunately just lump all rodents together (which seems a mistake to me, mice are only 1oz and rats can be around a pound!). Either way, that’s between seven percent and 15 percent of cats that willingly hunt rats. The majority of cats just aren’t interested in rats.

I also think that these anecdotes that keep coming up betray how we think about our domesticated animals. When we think of them as individuals, we are quick to say “oh, my cat is a big ratter!” or “oh, my cat just takes the tails off skinks she’s useless.” But we are also very quick to ascribe that behavior to ALL cats, to say that if one cat kills rats well, they all must have the same bloodthirst.

But cats, like dogs, like humans, like many other species, have individual personalities. A single cat’s behavior doesn’t reflect on the whole group. I think of the ratting cats as the MMA cage fighters of the cat world. They’re in it to win it, but most other cats are not about that life.

If you’ve got a mouse problem? Sure, enlist a cat. But if you’ve got a rat problem? Most of the time, try something else.

🗓️ References

• Parsons et al. Temporal and Space-Use Changes by Rats in Response to Predation by Feral Cats in an Urban Ecosystem. Front. Ecol. Evol., 26 September 2018. doi: https://doi.org/10.3389/fevo.2018.00146 

• Dickman and Newsome. Individual hunting behaviour and prey specialisation in the house cat Felis catus: Implications for conservation and management. Applied Animal Behaviour Science, Volume 173, December 2015, Pages 76-87. doi: doi.org/10.1016/j.applanim.2014.09.021

• Murray MH, Buckley JY, Magle S. Surveillance of Anticoagulant Rodenticides in Free-Roaming Outdoor Cats (Felis catus) in Chicago, Illinois, USA . The Journal of Wildlife Diseases. Published online 27 November 2025. doi:10.7589/JWD-D-25-00092

🚀 Where have I been

• I wrote about how tourist honeybees, sent over Irish heaths, might impact the permanent bumblebee residents. Because honeybees? They’re doing fine. But bumblebees? We only have so many.

• I also wrote about a new and complex pain pathway that might help explain why people who have high levels of circulating estrogen might be more sensitive to gut pain.

🚀 Where have you been

• Is it reading about this maverick scientist, who is a REAL scientist at the NIH…who also went and brewed a vaccine in his BEER at home? A fascinating story with a lot of interesting but difficult ethical implications.

• Is it reading about the politicians who celebrated cutting foreign with a cake…while people around the world starve? It’s a hard story, but a very critical and important one.

• People often have to think about whether to speak out, or whether to stay safe. The results of a new study? “Be bold,” said Daymude. “It is the thing that slows down authoritarian creep. Even if you can’t hold out forever, you buy a lot more time than you would expect.”

• In that vein: Congress rejected the 55% cut to research funds (that’s a link, why is that not showing up?!) proposed by the administration. They did not do that because no one said anything. Instead, they did it because scientists and science lovers fought, very, very hard.

• Don’t hold the butter, I guess. The new nutrition guidelines are out, and they appear to be entirely conceived of by paleo bros. I’ve got a LOT of thoughts on this.