Our family has always loved cats. I remember as a child growing up we always had quite the menagerie of cats and kittens running around. They're wonderful pets when they're socialized properly, and are even quite useful around homes and farms as natural hunters. Keeping pest populations under control around buildings and farmsteads has traditionally been the job of our feline companions ever since they first arrived with the European colonists several hundred years ago. Today they remain cherished pets, pesky strays, and even wild, free-ranging predators that are often seen hunting along ditches and roadsides. But when cats compete with wildlife in catching and consuming native prey species, their efficient hunting skills become cause for concern.
Domestic cats are descended from an ancestral wild species, Felis silvestris, the European and African Wild Cat. The domestic version, Felis catus, is now considered a separate species, but they are similar to their wild relatives in appearance and in many behaviors. This is particularly true in their hunting and other activities, which remain essentially unchanged from that of their ancestors. Cats free to roam outside have easy access to wild animals and often take a great toll on local populations of native small mammals and birds. There have been extensive studies of the feeding habits of free-ranging domestic cats over the last 50 years and encompassing four continents that indicate 70% small mammal species and 20% bird species when evaluating their prey. A variety of other animals comprise the remaining 10%. The diets of these wild cat populations generally reflect the food that is locally available to them. Some of the animals killed are considered pests such as house mice, rats, and meadow voles, while others include many native bird species and mammals that also may be adversely affected by other ecological factors such as loss of habitat, disease, or pesticide use. It is in these stressed situations for prey species that cats as predators have the most devastating impact.
When cats are present in large numbers in a particular habitat, they often compete with natural predators as they catch, kill and eat many of the same animals that the native predators do. They sometimes outnumber the natural predators and can reduce the availability of prey animals for species such as hawks, foxes, and weasels. These free-ranging cats also transmit to wild population's diseases such as the feline leukemia virus and feline distemper, as well as an immune-deficiency disease that can pose a serious threat to native wildcats such as bobcats, lynx, and mountain lions. Cats have an advantage over many wild animal species in that they are often protected by their human owners from disease and from predation by other species. This is not true of natural predators which often succumb to disease outbreaks and whose numbers are influenced by competition with others of their own kind for food sources and habitat.
Because cats have a supplemental food supply provided by their human owners, they are not affected by fluctuations in prey populations. Numbers of native predators tend to decline when prey species become scarce, but cats eating their main meals from a well-filled food dish experience no ill effects and continue to hunt, often taking species that are even rare or endangered. Their high numbers in some areas are attributed to a lack of territoriality that would naturally occur in wild animal populations, therefore they are sometimes found in much higher densities than are native predators such as foxes, raccoons, and skunks. They may also form large breeding colonies when wild and unchecked, and their desire to catch prey is a strong instinct. Their motivation to hunt remains a force even when they are fed a regular diet, and so they simply continue to stalk and capture.
What can we do as cat owners to protect our wildlife and reduce the impact of cats on native species? We can begin by limiting our pets to those that we can reasonably care for. We must control their numbers by spaying and neutering, and we can encourage others to do so. This will help keep feral (wild) populations of cats from becoming too dense in an area. Confining cats indoors if at all possible will limit reproduction and predation on local wildlife, and will help prevent the spread of disease. Since cats often stalk birds in backyards, we can locate our feeders away from areas where cats can hide under cover of brush as they wait to ambush the birds that come to feed. Bells on collars are generally ineffective, as even if they ring it's usually too late for the prey being stalked. Keep garbage secured and remove outside pet dishes. Don't feed stray cats, and never release them in rural areas. It is an inhumane way of dealing with unwanted strays as cats experience hardship in unfamiliar areas, even if they are good hunters. Instead, contact local animal control agencies for help.
Cats can be very affectionate pets, and we enjoy their lively antics and endearing personalities. Having cats and other pets around as a kid taught me some of my first lessons in respecting and caring for other creatures. Our own cats are getting older now, and our daughters always ask about their welfare in their phone calls home from faraway places. "Is everyone still alive?" they ask. "You'd tell us if something happened, wouldn't you?"
There is, however, one problem. One of our cats is very energetic and enjoys capturing small mammals from the woods and fields around our home. He's small and agile, and he's very good at it. He particularly enjoys stalking birds, and I often see him lying in wait to ambush them as they buzz around our backyard feeders. In addition, we come home every so often to a little "surprise gift" that has been left for us on a porch step or near the front door.
Aside from confining the cat permanently, I'm not quite sure what the answer is. His strong hunting instinct really puts the cat-lover in me at odds with the naturalist. I suppose it's possible that as he ages, he will slow down as the others have and curtail his habit of chasing down creatures that he doesn't need to kill for survival. We can always hope.
In the meantime, life in the outdoors remains interesting. So, I guess I'll just try hard not to cringe the next time I see a dead field mouse on my doorstep.