Cannibalistic Dads Contributing to Eastern Hellbender Declines

Male Eastern hellbender normally tends their young, but lately they’ve been devouring them instead.

Eastern hellbenders once swam in at least 570 streams in the eastern and central U.S., says Bill Hopkins, an ecologist at Virginia Tech. But numbers of the craggy, beady-eyed amphibians have plummeted in recent decades, with only about 126 streams now harboring healthy populations—and scientists didn’t know why.

To solve the mystery, Hopkins’s team placed hundreds of concrete nest boxes in streams in southwestern Virginia. For eight years, they snooped on 182 nests, checking them every few days during the breeding season. In 60 percent of those nests of Eastern hellbender not a single larva survived, most commonly because of whole-clutch cannibalism: the male had gobbled up hundreds of eggs. These cannibal dads had bulging bellies and a tendency to regurgitate the eggs when handled, the team reported in the American Naturalist.

The researchers’ documentation of egg survival rates across time is “incredibly impressive,” says Hope Klug, a behavioral ecologist at the University of Tennessee at Chattanooga, who wasn’t part of the study. Cannibalism of offspring isn’t unusual among animals, Klug says, explaining that parents may nutritionally benefit from consuming some offspring that they suspect won’t survive.