Main | Monday, March 21, 2011

The Cat Is An Invasive Species

According to the authors of a first of its kind study on bird mortality, the American housecat is a "non-native, invasive species" responsible for the deaths of 500 million North American birds annually.
Nearly 80 percent of the birds were killed by predators, and cats were responsible for 47 percent of those deaths, according to the researchers, from the Smithsonian Institution and Towson University in Maryland. Death rates were particularly high in neighborhoods with large cat populations. Predation was so serious in some areas that the catbirds could not replace their numbers for the next generation, according to the researchers, who affixed tiny radio transmitters to the birds to follow them. It is the first scientific study to calculate what fraction of bird deaths during the vulnerable fledgling stage can be attributed to cats. “Cats are way up there in terms of threats to birds — they are a formidable force in driving out native species,” said Peter Marra of the Smithsonian Conservation Biology Institute, one of the authors of the study.
Dr. Marra says cats "are like gypsy moths and kudzu — they cause major ecological disruption." My own disruptor is often reduced to quivering impotent rage by the pigeons that taunt her daily from our fire escape. "One of these days, you miserable flying rats. One of these days."

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