It's often said that man is the only animal who kills for fun, but that's actually not true. Animals that thrill kill are actually pretty common; scientists call it "surplus killing." Animals that kill for no reason range from mammals to reptiles, and even insects in some rare cases. So, which animals kill for sport, and how do they do it? The subject is just as fascinating as it is horrifying.
Over centuries of study, scientists have found animals use tools like humans, animals use disguises like humans, and now we know that they sometimes kill for fun like humans, too. By fun, we mean they don't do it over territorial disputes, in self-defense, to get food, or to move up in the pack hierarchy. These animals kill for apparently no reason whatsoever. And here's a little spoiler: some of them might be living in your house right now.
Everyone knows that dolphins are very smart animals, and that they can be trained to do a whole bunch of tricks and tasks. What you might not be aware of is the fact that dolphins can also be vicious killers.
Back in 1997, a bunch of dead porpoises washed up in the coast of Scotland and in Virginia, as well. When biologists studied the bodies it was revealed that the porpoises had died of broken ribs, ruptured livers, and punctured lungs, and they were bruised all over their bodies. With more research, scientists found bite marks that pointed to attacks from bottlenose dolphins.
The weirdest thing about this is that porpoises do not attack, harm, or generally mess with dolphins. And dolphins have no reason to attack or eat porpoises. Also, the method of killing was a slow, precise, and focused one. If the dolphins had wanted to cause fatal harm, they had the ability to do so much more quickly. The only explanation that remained for scientists is that the dolphins had killed the porpoises for no real reason at all, and that they had prolonged the death just for fun.
When you see your house cat playing with a toy, you probably think something like "aw, how cute!" Well, as cute as that may be, your cat is actually showing signs of killing for sport, even by playing with a simple toy. The kicking it does with its back feet is actually a move to disembowel prey, and that adorable little pounce is meant to pin an animal down. When it tosses its toy around? It's actually a method for breaking a small animal's neck.
Every year, cats are responsible for the deaths of billions of animals, most of which are never even eaten, so why do they do it? Well, they do it because they find enjoyment in the hunt and in the kill. They like chasing things, they like having live prey, and they like killing more than they like eating. This can be so devastating for wild bird and rodent populations that some countries (such as New Zealand) even are pushing to ban cats as pets!
Foxes are known for being very clever animals, and also for being agile hunters. For the most part, foxes have to scrape and search for food, especially during cold winters. However, in Australia, the winters aren't generally cold or harsh, and foxes end up being one of the most harmful invasive species the country has.
Foxes have shown on multiple occasions that they are not above surplus killing. They have killed tens of wallabies in a single night without eating a single one. They have attacked chicken coops and then eaten only one or two of the dead birds. In one particularly horrifying incident in 1994, about 1800 little penguins had come ashore to lay their eggs on Granite Island in South Australia. Things were going fine until a fox managed to get onto the island by means of a causeway. Over the course of the next three days, the fox killed 74 penguins, only eating a few. It seems the rest of them were just killed for grins, then left there to rot.
Leopards are a serious problem for farmers in South Africa, but in Cape Province it can get particularly bad. It seems that, unlike many other animals, leopards will participate in surplus killing regularly, and just leave the slaughtered, uneaten animals in the field. In fact, out of 104 recorded incidences of a leopard killing livestock, well over half involved surplus killing and uneaten remains.
And we're not just talking one or two animals every time, either. In the worst incident in 1986, it was recorded that a leopard killed 51 sheep and lambs in a single incident. Obviously these animals were not killed for food or for territorial purposes, so it stands to reason that they were slaughtered just for the thrill.