Impacts of Free-ranging Pets on Wildlife

Cats and dogs are domesticated predators. They have natural prey-chasing, capturing, and killing instincts. As a result of this and the large numbers of them in Florida, cats and dogs have the potential to severely impact local wildlife populations. In addition to reducing populations of species and limiting the number of prey items for native predators, free-ranging pets can cause other problems. For example, they serve as important reservoirs for human and wildlife diseases like ringworm, toxoplasmosis, leptospirosis, distemper, and rabies. They may be an important factor in introducing these diseases into susceptible wildlife populations. Dogs kill turtles and other wildlife. My own Australian silky terrier killed a young blue jay, and several frogs and lizards in my backyard. Exotic snakes and other pet predators can also have local impacts if released into the wild. But the pet that is by far the most devastating on wildlife populations is the furry feline. While a few species such as great horned owls and coyotes may think of cats as delicacies, many wildlife populations are threatened by "outside" cats that are allowed to range freely.The instinctive hunting and killing behavior of cats is extensively documented. Unlike wild predators that kill to eat, cats kill impulsively even when they are not hungry. Animals that nest or feed on or close to the ground such as cardinals, bobwhites, towhees, wrens, rabbits, and lizards are most susceptible. At least part of the population declines experienced by Florida's endangered beach mice are due to domestic cat predation. A Michigan study provided some insight into the impact of a single cat on local prey. During an 18-month period, one well-fed, domestic farm cat killed at least 60 birds and 1,600 small mammals. A study in England estimated that over a million birds are killed each year there by free-ranging cats.Although it is impossible to determine the extent of this problem in Florida, estimates are astounding. Several thousand stray cats are picked up by county animal control departments in Florida each month (for example, Orange County averages almost 670/month). If each cat killed only one animal each month, tens-of-thousands of animals would be killed each year here. This is a conservative estimate, because studies have shown that cats kill more than one animal per month (almost 100 were killed each month by the cat in the Michigan study), and we
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