The first wild population of endangered black-footed ferrets that started from captive-bred animals, once feared to have died out, has survived and is growing, researchers say.
The latest survey, from 2006, reports nearly 200 ferrets in Wyoming's Shirley Basin, says Martin Grenier of the University of Wyoming in Laramie. They descend from animals released there between 1991 and 1994. The new census fits in with an exponential population growth that Grenier and his colleagues have seen in surveys since 2000, they say in the Aug. 10 Science.
The ferrets' future depends on the wellbeing of their main food item, the prairie dog. The small ferret population also remains vulnerable to disease. Even so