Feral feline status: Cat's ill, cats kill

Feral cats have been spreading in the wild in Hawai'i, and new research indicates that all's not well with the environment, nor with the cats themselves.

The felines, some of which are just a generation or two out of domesticity, and others dating their heritage back to early European sailing ships, not only eat imported birds, like meijiro, cardinals, shama thrush and others, but they also attack native birds, often in the most remote terrain.

Wildlife scientists Steven Hess, Daniel Goltz, Raymond Danner, Kevin Brinck, Paul Banko, Heidi Hansen and others, working from the U.S. Geological Survey's Pacific Island Ecosystems Research Center at Kilauea, conducted a series of capture and test experiments on feral cats on Mauna Kea.

They've also been looking into cat issues in other ways. One is cameras set at bird nests.

Cats are opportunist feeders. A chick in a nest? They'll kill it, even if sometimes they don't eat it, Banko said. He estimated 10 percent of Mauna Kea's endangered palila chicks are taken each year by cats.

They also attack the Hawaiian state bird, the nene, sometimes eating mother geese as they sit on nests on the ground.

They will creep into seabird burrows, and take adults and chicks, which have no way out once the cats are in the entrance to the burrow.

A lot of the cats carry disease. Many have the cat form of HIV, feline immunodeficiency virus. Some also have the cat form of leukemia, feline leukemia virus.

And, as in most populations of cats, there is toxoplasmosis, a protozoan disease that doesn't make otherwise healthy cats ill, but can infect other animals. The last wild individuals of the critically endangered Hawaiian crow were pulled out of the wild into captivity when it was found that some were dying and others were ill from toxoplasmosis.

Cats pass toxoplasmosis through their feces, which grazing animals can inadvertently take up while feeding, and creatures like rats and pigs can get by feeding directly on cat scat. The disease can be passed to humans through the incompletely cooked meat of infected animals, or by directly contacting and ingesting infected cat droppings—for example by wiping your mouth after gardening in soil where a cat's done its business.

In humans, it's generally only a problem for the fetuses of women pregnant when they are infected, and in people with compromised immune systems. Toxoplasmosis can be treated if it's detected.

© 2007 Jan W. TenBruggencate