Editorial Board / New York Times
There is nothing simple about counting grizzly bears. But counting them accurately will help determine whether they remain on the endangered species list or are delisted. The Interior Department’s Fish and Wildlife Service says there are about 700 grizzlies in the greater Yellowstone ecosystem, more than the 500 it deems essential for a healthy population. But a new study in the journal Conservation Letters calls those numbers into question.
A count is a projection, based on assumptions about the reproductive and survival capacity of grizzlies. The agency assumes that the bears live until they are 30 years old and reproduce at constant rates all along. This is a mathematical convenience, not a biological observation. The study argues that the inaccuracy of previous counts means that biologists know less than they think and concludes that grizzly numbers appear to have increased simply because government biologists…
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