Cats are popular pets, yet they have been employed as working animals to help manage rats and mice, pests in both urban and rural areas, for thousands of years. It is only normal for domesticated cats to prey on wild birds and other animals; they act on their instincts. However, from an ecological standpoint, the impact of that predation has been anything but natural, and it has even resulted in the extinction of certain species. Cats prey on animals in large numbers because they are a species that has been introduced by humans all over the world and maintained by us in numbers that exceed those of natural predators. This is an extension of our detrimental effect on our environment. It is our responsibility to prevent this from happening.