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Global Stewards - Green Eco Tips for Sustainable Living

Top 20 Reasons to Keep Cats Indoors

To Protect Wildlife and Humans

  1. Outdoor domestic cats are a recognized threat to global biodiversity. Cats have contributed to the extinction of 33 known species and continue to adversely impact a wide variety of other species, including those at risk of extinction. The International Union for the Conservation of Nature (IUCN) lists domestic cats as one of the world’s worst non-native invasive species. Outdoor Cat Killing a Rabbit
  2. The top human-caused threat to birds in the U.S. and Canada is by domestic cats, which number well over 100 million in the United States. Cats kill approximately 2.4 billion birds every year in the U.S. alone.
  3. A wide variety of wildlife, including birds, mammals, reptiles and insects are killed by cats. Studies conducted at the Wildlife Center of Virginia found that 84 different species of wildlife were brought to the center after being injured by a cat — 21 species of mammals and 62 bird species.
  4. Even if the bird or other animal escapes, they often die later. Cats carry bacteria in their mouths that overwhelm small animal immune systems. Injuries and a high degree of stress usually kill a small bird or mammal even after it escapes the cat.
  5. A significant number of wildlife victims are parents defending nests and fledglings, meaning that not only was the individual bird lost, but also more than likely her young as well.
  6. The mere presence of cats outdoors is enough to cause significant impacts to birds. Because cats are recognizable predators, even brief appearances near avian nest sites leads to at least a doubling in lethal nest predation of eggs and young birds by third-party animals and reduces by a third the amount of food brought to nestlings.Outdoor Cat Killing a Bird
  7. House cats are considered "super predators" because:
    • they are an introduced predator (so wildlife has not evolved to defend themselves)
    • they exist in unnaturally large numbers, far greater than any natural predator
    • they are prolific breeders and tolerate other cats in their territories, so large numbers are maintained
    • many have a constant food source and are often more fit than natural predators
  8. Cats are the most common spreaders of the parasite toxoplasmosis gondii. Infection can lead to neurological problems, and sometimes death, in both wildlife and humans. Cats have been found to spread the disease widely, even in remote areas, through defecation. 25% of humans are infected, which has resulted in increased risk of eye lesions, deafness, seizures, mental retardation, blindness, schizophrenia, Alzheimer’s Disease, autism, obsessive compulsive disorder, memory loss, multi-organ failure, and even death. As many as 74% of all domestic cats in the United States will be infected by T. gondii during their lifetimes. 
  9. Cats are the top carrier of rabies among domestic animals in the United States and have outpaced dogs for decades. If an animal is bit by another rabid animal it usually dies quickly. For humans, it is also fatal if left untreated.

To Protect the Cats Themselves

  1. Cats who are kept indoors live an average of 12 to 15 years - outdoor cats live on average 3 to 10 years (depending on the risks in the environment).
  2. Outdoor cats are at risk of being:
    • wounded in fights with other animals (many times resulting in dangerous abscesses)
    • hit by cars (an estimated 5.4 million are hit a year)
    • eaten or injured by a predator such as owls, raptors, coyotes or dogs
    • killed by inadvertently ingesting poisons such as antifreeze, rat poisoning or toxic plants
  3. Antifreeze Warning for Cats
  4. It’s harder for owners to identify health problems early (such as urinary tract disorder, renal failure due to old age, genetics or ingesting poison, and disease), before they become life threatening. When a cat is sick or injured, their natural instinct is to hide in silence because this is their primary defense mechanism from predators.
  5. Cats can be exposed to infectious diseases such as:
  6. Cats can get fleas, ticks, ear mites, intestinal worms, and ringworm.Outdoor Cat Recovering from Abceess
  7. Cats can be picked up by animal control or a neighbor, and if missing identification, can be euthanized or adopted. Only 3% of cats turned into shelters make it back to their owners.
  8. Cats can get trapped inside structures such as garages, sheds, basements, or vehicles. They can also climb under the hood of cars and get injured or killed when the car is turned on.
  9. If cats are chased, they sometimes don't return home and can end up as a stray.
  10. Cats can be endangered by sudden cold or stormy weather. They are especially at risk of hypothermia.
  11. Roaming cats may be at risk for animal cruelty. Sadly, some people have been known to shoot cats with BB guns or arrows, while some cats end up being trapped, abused and killed in the name of “sport” or “for fun.”
  12. Trees can be a source of some danger for cats who climb to a place where they are afraid or unable to climb down. In some cases, they may be up in a tree for days until they become so severely dehydrated and weak that they fall and suffer severe, serious or fatal injuries.

Take Action

Visit the American Bird Conservancy Take Action page to learn how you can help.


Cats and Birds (American Bird Conservancy)

Study Documents Dramatic New Impacts To Birds From Outdoor Cats (American Bird Conservancy)

Indoor Cats vs. Outdoor Cats (American Humane Society)

Keeping Cats Indoors Isn’t Just for the Birds! (American Bird Conservancy)

A Contaminated Environment (American Bird Conservancy)

Toxoplasmosis in Feral Cats: Health Risks to Humans and Wildlife (The Wildlife Society)

JWM Study: Domestic Cat Attacks Cause Variety of Wildlife Deaths (The Wildlife Society)

Cats Pas Disease to Wildlife Even in Remote Areas (ScienceDaily)

How Different Strains of Parasite Infection Affect Behavior Differently (ScienceDaily)

Should You Have an Indoor Cat or an Outdoor Cat? (WebMD)

The Top 5 Ways that Outdoor Cats Become Lost (HomeAgain)

Pet Statistics (ASPCA)

How Long Do Cats Live? (catster)

Five Most Dangerous Cat Diseases (Animal Planet)

Top 20 Reasons to Keep Cats Indoors (The Spruce)