"Part of what makes a grizzly bear a grizzly bear is their very long claws. It’s just something essential." So explains Canadian biologist Clayton Lamb, and in a piece for the Washington Post, Dino Grandoni elaborates. Those paws and claws are key to a bear's ability to hibernate (it digs out dens) and eat (it digs for edibles like rodents and roots). So when Lamb came upon four bears missing some of their digits in British Columbia, it gave him pause despite the small sample size. And as Grandoni writes, it sent Lamb on a 5-year search for an answer.
X-rays showed the presence of bone fragments, meaning the toes weren't missing since birth: They had once been there. But the breaks were straight ones—"as if toes had been cleaved on a carving board," reported Science—meaning they weren't torn off or bitten off by another animal. So his team investigated a theory: that the bears were getting their paws caught in baited traps meant to catch weasel-like animals called martens. In the past, that probably wouldn't have been possible, but a push for more humane deaths—meaning instantaneous ones—for the martens had led to the use of more powerful traps.
Motion-sensor cameras placed near four traps by Lamb's team confirmed all were visited and two were triggered by grizzlies in a two-week period. Then came the oddest part of the research: putting a dead bar's paw in a trap attached to a pickup "to determine the steady pull required to extract an adult foot from the ... traps," per the study, published in August in Wildlife Society Bulletin. The force didn't sever the digits. Lamb determined the trap would choke off blood flow, which would eventually cause the toe to die and fall off. "It’s fair to assume that there’s quite a bit of suffering over the weeks or months that these toes are actually falling off," Lamb said. His research led officials to require changes to the traps so that the openings are big enough for martens but not for bear paws. (Read more discoveries stories.)