May 24, 2007 Fingerprint The Little Weasels

The criminal justice system has long kept fingerprints of weasels, the kind who steal cars, rob stores and get sent up the river. Then there’s the carnivorous mammal called the fisher, a species of weasel that’s once again doing pretty well up the Hudson River, in northern New York, after almost being driven to extinction in the 1930s. And now researchers can track fishers, by treating them like criminals—they fingerprint them. Which is quite a trick, since fishers don’t have fingers. But their little paws do have patterns that are unique to each individual—they’re the only carnivores known to have such discernable prints.

Where human fingerprints consist of ridges, fisher prints are patterns of dots. And the dots stymied the computer software used to compare human fingerprints. So scientists from the Wildlife Conservation Society and other groups teamed with experts from the New York State Department of Criminal Justice to develop a new technique to analyze and compare fisher prints, leading to more accurate population estimates. The fishers wander into food-baited boxes, leave prints and pop goes the weasel out again. Which some might say makes it virtually identical to the criminal justice system.