When a polar bear kills, it doesn’t just eat. It feeds a whole ecosystem

Sheena Goodyear · CBC Radio

· Posted: Oct 29, 2025 3:28 PM EDT | Last Updated: October 29

LISTEN | Full interrogation with Holly Gamblin:

When a polar carnivore kills its prey, it’s not the lone 1 who gets to reap the bloody benefits.

Many of nature’s apex predators defender their meal from scavengers until they’ve gobbled up each past morsel and licked the bones clean. But scientists accidental polar bars thin to devour what they need, and permission the remainder down for different Arctic critters to munch.

A caller study, published the diary Oikos, estimates that 1 polar carnivore provides astir 300 kilograms of nutrient per twelvemonth for different animals to dine on. With 26,000 polar bears successful the Arctic, that’s a whopping 7.6 cardinal kilograms of nutrient annually. 

“If we suffer polar bears from the Arctic … thing tin regenerate that,” Holly Gamblin, wildlife biologist astatine University of Manitoba, told As It Happens host Nil Köksal. “There's nary different comparable taxon that is doing this.”

Sharing is not needfully caring

By sharing the spoils of the hunt, polar bears are providing what’s known arsenic an “ecosystem service,” says Gamblin, the study's pb author. And it’s successful stark opposition to the behaviours of galore different apical predators, similar upland lions and wolves. 

But polar bears, she says, aren’t doing this retired of the kindness of their hearts. 

“I can't accidental that they person this altruistic quality astir them,” she said. “But what they bash person is this blubber specializer diet.”

Polar bears, she says, truly lone privation to devour 1 happening — and that happening is blubber, the heavy furniture of warming abdominous nether the tegument of marine animals similar seals and penguins.

“They're usually stripping that first,” Gamblin said. “They don't truly attraction truthful overmuch astir the nutrient that's near over. It's hard for them to digest that protein.”

Geoff York, a polar carnivore researcher who wasn't progressive successful this study, says polar bears volition spell beyond the blubber if they’re bare enough, but they decidedly similar those fatty morsels.

“Much similar brownish bears on salmon streams go much selective arsenic they summation weight, eating lone the eggs of spawning salmon and leaving the carcass, polar bears successful bully assemblage information besides absorption connected the abdominous from marine mammal prey,” York, manager of probe astatine the conservation radical Polar Bear International, said successful an email.

Holly Gamblin, wildlife biologist astatine University of Manitoba, poses with an unconscious polar carnivore connected Hudson Bay arsenic portion of a live-capture and merchandise conservation monitoring program. (Submitted by Holly Gamblin)

And 1 Arctic carnivore’s trash is another’s treasure.

The study, which includes scientists from the University of Alberta, confirmed 11 vertebrate taxon person been documented scavenging polar bears’ discarded meat, including wolves, foxes, gulls, hawks, snowy owls and grizzly bears.

The squad besides identified different 8 taxon arsenic imaginable scavengers due to the fact that they've been spotted connected the oversea ice, but haven't been observed eating polar-bear cast-offs.

Chief among the benefactors are Arctic foxes, who are known to travel polar carnivore tracks mode retired onto oversea crystal successful the anticipation of snagging immoderate meaty scraps.

“Arctic foxes are benignant of considered the champion person of polar bears,” Gamblin said. “So polar bears making kills and fattening up tin really interaction Arctic fox populations from twelvemonth to year.”

Arctic foxes are 1 of the creatures who payment astir from polar bears' leftovers. (Maja Hitij/Getty Images)

But polar carnivore populations are declining rapidly. 

One survey from past twelvemonth estimates that polar bears could vanish wholly from Hudson Bay implicit the adjacent mates of decades due to the fact that of melting oversea crystal from clime change. 

Gamblin and her colleagues enactment that polar carnivore populations declined 32 per cent successful the Western Hudson Bay betwixt 1987 and 2011, and 44 per cent successful the Southern Beaufort Sea betwixt 2004 and 2016. 

Those losses unsocial magnitude to 323,000 kilograms successful mislaid nutrient resources for different Arctic animals, the study's authors say.

That’s conscionable 1 much crushed wherefore it’s important to support polar bears, says York.

“The imaginable nonaccomplishment of apical predators is not astir the nonaccomplishment of a azygous species, but the nonaccomplishment of a cardinal subordinate successful the ecosystem that volition person domino effects crossed the Arctic,” helium said.