Cats can be great pets, low maintenance purring machines. Unfortunately, they are also active and effective predators.
There are many ways for birds to die. Among the human causes in the US, window collisions may kill a billion birds a year. Cars kill a fraction as many, some 200 million. Pesticides, power line and cell tower collisions, wind turbines, hunting, and oil spills may kill another 200 million.
But the big killer in the US is cats. It is estimated that outdoor cats kill 2.4 billion birds a year in our country. With the exception of habitat loss, this number dwarfs all other current human-caused bird mortality combined.
Many of the studies are small, but they reveal a grim pattern. Cats kill nearly 50% of suburban songbird fledglings. Pet cats average one wildlife kill per fifty-six hours outdoors. They eat or abandon most of their kills at the kill site, not on the owner’s doorstep – belying many owners’ hopes that their pet is too domesticated to follow its instincts. A University of Nebraska study pins thirty-three bird extinctions on cat predation worldwide.
Feral cats number between 30 to 80 million in the US, according to World Animal Foundation estimates. If their kill rate equals that of pet cats, simple arithmetic indicates kills of small animals – birds, lizards, voles, etc. – of nearly 8 billion per year.
Despite being an invasive species, domestic cats are often maintained in the wild. Well-meaning people develop feeding stations that create unnaturally dense colonies. These colonies turn city parks and neighborhoods into native species kill zones, contributing hugely to the declines of American songbirds.
Further, these feral cat concentrations create sinks for the spread of disease and suffering, Feline leukemia and panleukopenia are highly contagious, disabling diseases of outdoor cats. FIV – the cat version of the AIDS virus – spreads mostly through saliva in cat-fight bites.
People, too, are at risk from cat-spread disease. Rabies is found in three times as many cats as dogs, possibly because of their greater involvement with wild animals and the lack of vaccination.
The toxoplasmosis parasite, famous for warnings to pregnant women against cleaning cat litter, can infect any warm-blooded being but only reproduces in cats. Over 70% of cats are expected to carry the parasite at some point in their lives, and they release hundreds of millions of oocytes that can deliver the disease for years through gardens and parks where they defecate. In people, our immune system usually prevents symptoms. But the parasite attacks the brain and is associated with deafness, eye lesions, and a wide range of behavior disorders including Alzheimer’s, autism, obsessive-compulsive disorder, and schizophrenia.
Some solutions to these bird kill and public health problems are easy. Pet owners who keep their cats indoors will protect both wildlife and their cats.
Feral cat problems are tougher to tackle. Trap-Neuter-Release programs have been shown to be ineffective. Neutered cats still kill birds and spread disease, and neutering efforts do not keep pace with the influx of new cats. A single breeding pair can produce 400,000 offspring over seven years.
US governments spend over $50 million a year to reduce the problems posed by feral and stray animals. In Redding, city land is being used to support feral cat colonies.