Cats are an invasive species

A threat to human health and the environment

Welcome to Science with Shrike! With cat consumption in the news, it is worth discussing the absolute disaster that outdoor and feral cats are for the environment and for local ecosystems. As a reminder, it is illegal to kill cats and dogs by any means other than taking them to a vet for humane euthanasia.

But I like cats!

This might not be the article for you. Shrike’s opinion is the estimated 30-40 million feral cats in the US is too many to be adopted by everyone, which means they need to be culled. Shrike has no problem with Indoor cats, and none of this is meant to argue against indoor cats, or to support breaking into someone’s home to abduct their pet to eat, perform voodoo or any other harm to the animal. If the cat is accessible outdoors unsupervised, and it isn’t an unintentional escape, that’s not a pet.

Even before you had to worry about people in the neighborhood eating your outdoor cat, leaving your cat outdoors was negligent. One study in the UK that followed a cohort of cats, found ~4% of them were hit by automobiles, with ~75% of these being fatal. They found cats in rural areas were at higher risk of getting hit by a car. Feline immunodeficiency virus (FIV) is lethal to unvaccinated cats, and is spread through contact with infected cats. Stray dogs (another problem!) also mangle feral and free-roaming cats. This all assumes the feral cats are fed, and do not die of starvation. Overall, feral cats survive for an estimated 2-3 years vs the average 12 years an indoor cat enjoys.

The counter-argument is the claim that cats “need” to be outdoors for their mental well-being. The problem with this argument is there is minimal evidence provided beyond the owner’s “feelings”. Would you want your cat safe in a loving home, or out where it can die alone?

What is the impact of feral cats?

Feral cats hurt both human health and the environment.

From a human health standpoint, they carry many diseases. Most notable to human health is rabies, which is fatal. Toxoplasmosis comes up because it is common. However, aside from pregnancy, HIV or some other immunocompromised state, it does not cause many major problems. There are some suggestions it is linked to neurologic phenotypes, but the associations are weak. Ocular toxoplasmosis is also an issue, and impacts ~125,000 people per year.

But cats can also carry (and transmit) Cat Scratch Fever (~30,000 cases per year), Lyme Disease (via ticks), hookworms, roundworms and Plague (via fleas).

The environmental impact is also extreme.

When it comes to bird kills, the top 3 are cats, construction (glass on buildings, habitat destruction) and vehicles. But the cat kills outstrip all the rest by a large margin.

It’s not even close. Source

Cats also kill billions of small mammals. While most hope these are rats and mice, it’s a much larger range of prey. Cats in Australia get credit for driving Australia’s high rate of extinction. On islands, cats and rats drive the extinction of many native species. As a result, cat elimination from islands is encouraged.

Most of this wholesale slaughter is done by cats for fun. Only a fraction of the animals killed by cats are eaten.

But Trap-Neuter-Re(abandon) (TNR) fixes the problem, right?

Lol, no.

At first, trap-neuter-return (aka trap-neueter-re-abandon), was meant to control the cat population. The pretzel logic was that if you removed all the cats in an area, you’d somehow get more cats than if you neutered the cats and returned them to defend territory. This failed. Now proponents of trap-neuter-reabandon have moved the goalposts to claim it benefits the cat’s health.

2-3 year average survival vs 12 year average survival argues otherwise. SuRvIvAl iSn’T hEaLtHsPaN. Shrike knows. But to make that argument, you are claiming the 10 extra years of life indoors is miserable torture. With animals, we euthanize animals when they are in unrelieved pain and distress. So that 12 year average is a reasonable approximation of healthspan, while we cannot make the same assumption about the 2-3 years outdoors spent mass-murdering wildlife and spreading disease.

Cat solutions

Indoor cats are fantastic. Keep them inside, and they are safe. Give them access to a window and they can see things outside without the attendant risks. Harnesses are another solution if you want to attempt “walking” your cat. Note that cats slip collars, so a secure harness is needed. Also, many cats dislike the idea of being taken for a walk. If you ownd a house, a catio is also good long-term solution. The cat is fully fenced in, but can feel, hear and move around the outdoors.

For control of rats and other rodents, a rat terrier team is more effective than a barn cat or four.

There are few legal solutions to deal with outdoor cats. Live trapping them (but only on nice days when it’s not too hot, cold, rainy, etc) and letting animal control collect them is your only legal option in most cities. Many animal control centers will release the cats. It’s possible you can find a kill shelter. Possibly you could find a vet willing to euthanize the cat you trapped. However, vets shooting them with arrows, even with clean kills, are not permitted. If you live on a farm, you get more leeway for shooting animals that threaten your livestock and crops.

If you have money to burn, you might be able to find a lawyer and sue the vets/cities that practice TNR on the grounds it violates the various environmental laws prohibiting the intentional release of a non-native species that have demonstrable negative impact on endangered species. Some of these may vary by state (eg Hawaii and Florida likely to have stricter state-level laws). Best of luck to you.

Or we could change the laws across the board to treat cats like other invasive and destructive mammals, such wild hogs and rats. But until we decriminalize catch, kill, and eat, there needs to be equal application of the law.