The Case for Indoor Cats

Keeping cats indoors saves wildlife. It also protects cats, humans, and the environment.

While most of us love our kitties, free-roaming outdoor cats are a major threat to wildlife. These non-native predators kill billions of birds, small mammals, reptiles, and amphibians each year (See the Report of the Free-Roaming Cat Stakeholder Workgroup below for extensive citations for the statistics used on this page).

Sadly, when wild animals are attacked by cats, their chances of survival are extremely low, due to both the severity of direct injuries and the very aggressive infection that invariably occurs with even minor cat-related injuries such as mild scratches or bites. Even with veterinary treatment, Wildlife Center research shows that survival rates are very low. Without treatment, chances for survival are almost zero!

"While it is convenient to tell ourselves that our cats do no harm when allowed to roam freely outdoors, the facts prove otherwise. Unlike wild predators who hunt specific prey for food, cats hunt—and kill—anything they can, just because they are cats!” 

–  Wildlife Center President Emeritus Ed Clark

What You Should Know

  • While the hunting behavior of cats is instinctive, cats (just like domestic dogs) are not wild animals, nor are they a natural part of the ecosystem. They are an invasive predator whose presence is a disruption to the local environment. A 2013 study by the Smithsonian Conservation Biology Instituteand the U.S. Fish and Wildlife Service estimated that free-roaming cats kill between 1.3 and 4.0 billion birds, and between 6.3 and 22.3 billion mammals annually in the U.S.
  • Cats impact more than just the wildlife they catch; the mere presence of cats can cause additional stress on wildlife, particularly during the nesting season, when wild parents have been shown to avoid returning to their nests or dens for extended periods, to avoid leading these predators to helpless young. The study linked to above showed that the presence of a feline in the area reduced the growth rate of young birds by approximately 40%
  • Because they don’t always see the dead victims, many cat owners believe that their indoor/outdoor cats are not actually hunters and killers. However, research conducted by the University of Georgia found that a staggering 77 percent of wildlife caught by cats is either eaten or left at the site of capture. The number of animals brought home is only a small portion of the wildlife the cats are actually injuring or killing.
  • Free-roaming cats themselves encounter a variety of dangers and risks, including crossing roads, attacks by other animals and people, and exposure to disease, toxic substances, and severe weather. The American Association of Feline Practitioners’ 2012 position paper on free-roaming cats concluded that the welfare of outdoor cats is “severely diminished” compared to indoor felines.
  • Free-roaming cats present serious risks to public health and the environment. One of the biggest threats to health from free-roaming cats is toxoplasmosis. Humans and wildlife can contract this infection from several sources, but the only place the parasite can reproduce is in the intestines of cats. Ultimately, all sources of the infection can be traced back to contaminated cat feces. Toxoplasmosis from free-roaming cats can affect humans, domestic animals, zoo animals, and native wildlife. Rabies is another significant concern to human health. There are many wild rabies vector species (RVS) throughout the United States, including raccoons, skunks, bats, and foxes, but according to The Wildlife Society, “Cats ... are responsible for a disproportionate number of human exposures.”
  • Even cats that have previously been allowed to roam freely can live happy, fulfilled lives indoors. The transition can be challenging, but many valuable resources can help. Read the Wildlife Center’s guidance Bringing Your Cat Indoors.


Cat with dead bird in mouth

The Wildlife Center of Virginia’s Research on Free-roaming Cats and Wildlife

In 2016, The Journal of Wildlife Management published an extensive 11-year study conducted by the Wildlife Center of Virginia, which shows that domestic cat attacks are one of the most frequent and most lethal causes of animal admissions at the Center.

The study examined nearly 21,000 patient records, including 11,144 small mammals and 9,777 small birds, admitted between 2000 and 2010. Of this total, 2,970 patients (14%) were confirmed cat-attack victims. During that period, of all small mammals admitted due to cat attacks, more than 70 percent died or had to be euthanized. For small birds, the mortality rate was a staggering 81 percent.

Additionally, the Wildlife Center’s study graphically illustrates that free-roaming cats are not “just” killing mice and rats.  For the study period, 83 different species of birds and mammals were admitted due to cat interactions. Among the most frequent avian victims were Mourning Doves, Blue Jays, American Robins, and Northern Cardinals. Gray squirrels, chipmunks, cottontail rabbits, and flying squirrels topped the list for small mammals that fell victim to cats.

Summary of the Findings

52.7% eastern chipmunks admitted were cat attack victimsMammals

Cat attacks were the second highest cause of admission for mammals during the 11-year study period. Despite treatment, which begins immediately after admission, the mortality rate for cat-attacked mammals was 70.8 percent.

Those mammal species admitted with the highest percentage of cat interactions were Eastern Chipmunks (52.7% admitted), Eastern Cottontails (26% admitted), and Southern Flying Squirrels.


bird cat attack victims infographicThe overall songbird mortality rate for cat attack victims was 80.8% (despite treatment).

Of the 98 songbird species admitted during the study period, 62 species were affected—two-thirds of all songbird species admitted. Those birds admitted with the highest percentage of cat interactions were Northern Cardinals (22% admitted), Mourning Doves (20% admitted), American Robins (20% admitted), and Blue Jays.

All Species

When combined, the patients in the 11-year study that were most commonly harmed by free-roaming cats are (in order): Eastern Cottontails, Gray Squirrels, American Robins, Mourning Doves, and Blue Jays.

Larger birds and reptiles were not included for this particular study, but the Center has documented cases of raptors that have been attacked by cats (including Eastern Screech-owls and American Kestrels) as well as snakes, toads, and skinks.


Most patients admitted after interaction with a cat came in between April and September, with the majority of patients admitted in May and June.

Seasonal admissions graph