Here’s an interesting pair of questions I recently received:
Can cats live on wildlife catches alone, and what sort of diseases might they be risking if they do? I had a friend who lived in New Mexico, and he swore that his cat ate only chipmunks or some other kind of rodent.
Also, my youngest cat has caught five rats in recent memory, and eats the heads but nothing else. (Niiiiiiice.) Is that just the tastiest part, or is he a sadist?
There is no reason why, in theory, a cat could not live on wildlife catches alone. However, in practice I rather doubt that many cats could do it.
Cats are carnivores. In fact, the adorable little fluffball at the foot of your bed is actually, in many environments, what’s known as an apex predator. Apex predators are at the top of the food chain — they consume prey but are not standard prey for any other animal (although any animal can suffer from opportunistic predation). They share the apex predator title with some other impressive creatures such as great white sharks, bald eagles, and of course lions and tigers (and basically all other cats, large and small).
As carnivores, cats are capable of living on prey. Note that this does not simply mean living on meat. Cats evolved to eat the animals they catch essentially in their entirety — this means that they eat bones, organs, and even the grains and vegetable matter inside their prey’s intestines. A cat who is an especially good hunter may well be able to survive on prey alone.
However, I do not recommend leaving your cat to his own devices outdoors for many reasons. Starvation is the most basic risk for a cat who is left to fend for himself. Predators starve to death all the time.
Also, the predator-prey relationship is crucial to the transmission of many parasites in cats. Cats who hunt can be exposed to roundworms, toxoplasmosis, and some types of tapeworms. They also are at increased risk of exposure to gastrointestinal bacterial diseases, and to dangerous systemic infections such as bubonic plague.
Also, a hunting cat faces all the dangers of the great outdoors. These include hypothermia, opportunistic predation, motor vehicle injuries, trauma from falling from heights, cat fights, viral infections such as FIV/feline AIDS, and becoming permanently lost.
Environmentally conscious cat owners no doubt also would take issue with the impact of this sort of predation on local wildlife. Cats eat more than rats and mice, which are common and won’t be missed by many people. They also take out song birds, reptiles, and other rare forms of wildlife. This is not merely a theoretical problem: Cats in New Zealand have driven many bird species to extinction.
In short, the notion of a cat surviving by predation is an interesting mental exercise, but it’s a very bad idea in reality.
As for eating the rat heads, nobody knows why some cats prefer some parts of their prey to others. However, one thing is certain: Cats aren’t sadistic. They hunt because it is their instinct, and I doubt that any cat takes sadistic pleasure from killing a mouse, or a feather on a piece of string, or the point of a laser beam, or his owner’s toes when they move under the sheet. This activity is simply what cats do, and I’m convinced that there is no malice involved.