Modern cats have gradually lost some of their wild instincts through domestication. Domestic cats are not as fierce as wild cats and do not like to hunt small animals. However, this is not absolute. We still encounter situations where cats bring back dead small animals, such as birds or mice. This is not only detrimental to disease control and unhygienic, but also affects the ecological balance of species. So, how can we prevent cats from hunting wild animals? 
Before cat owners conclude that their cat is a cold-blooded killer, let's understand what mechanisms guide cats to do such things.
A recent study shows that cats are natural hunters, and both wild and domesticated cats have a significant impact on bird and rodent populations. Cats kill approximately one billion small animals each year in the United States alone. However, this does not mean they are evil animals; they are simply highly adapted to a carnivorous lifestyle of hunting.
Although cats have been domesticated by humans since around 10,000 years ago, like their feline ancestors, they still retain their hunting instincts and digestive systems capable of handling raw meat. However, many cats don't eat their prey, and sometimes they're even more ruthless in giving them a good death... (If you've ever had to catch a wounded mouse that's trying to escape, you're probably familiar with this behavior).
Spayed or neutered female cats are most likely to bring prey back to their owners, but they have their own reasons and purposes! In the wild, mother cats often bring home dead or injured prey to teach their kittens how to hunt and eat. Domestic cats have the same instinct, but because most modern female cats are spayed or neutered, they have no offspring to pass on these hunting wisdom and skills.
Simply put, when your cat leaves a dead mouse by your bed, it's acting as a dutiful mother and teacher, and you, its loving owner, are part of its feline family. The truth is, it knows you could never catch a plump, delicious mouse as cleanly and efficiently as it does, so it brings it to you!
