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Wildlife: Having a Meltdown
Here’s another grim Arctic tale brought to you by global warming: Early snow melt is causing the snow caves of baby ringed seals to collapse too early.
Without these hideaways on the sea ice, the still-nursing seals become sitting ducks—left vulnerable to polar bears, ravens and gulls. And if seals disappear, ultimately their main predator will as well, says Brendan Kelly of the University of Alaska, who has been conducting studies of ringed seal behavior with Labrador retrievers, trained to sniff out the lairs.
“In Alaska, 90 percent of the polar bear’s diet is ringed seals,” says Kelly. “The bears may be getting a few extra calories from the pups now, but it will cost them a lot later when the adult seals aren’t there to prey upon anymore. They are the bears’ real food.”
Unlike other arctic seals, which must migrate south during winter, ringed seals are able to inhabit the Arctic all year. “This is largely due to their unique behavior of excavating breathing holes and lairs in the snow that covers the sea ice,” says Kelly. “Maintaining these holes allows ringed seals to remain in areas of continuous ice cover.”
Ringed seal adults build and maintain their lairs above breathing holes in the ice, using the stout claws on their front flippers to excavate snow. These lairs are easily adapted to suitable dug-outs where the females give birth in spring.
The snow caves provide the helpless pups with protection from predators and from the elements. Baby seals do not develop their insulating blubber until they are weaned. “Their white, woolly coat keeps them nice and warm until it gets wet,” says Kelly. “Then they can freeze to death.”
Besides earlier snow melts, scientists have documented other unusual weather events, including rain. If thawing temperatures cause den collapses that are then followed by freezing rain, the exposed pups will die. Ironically, says Kelly, the pups are freezing to death in the face of global warming.
“Yes, there are lots of seals that live on warm, sunny beaches,” says Kelly. “But what’s really key for biological adaptation in the face of climate change is the pace of that change. If it happens too rapidly, organisms can’t adapt.”
