Polar bears aren’t just the Arctic’s top hunters — they’re also accidental caterers, leaving behind millions of kilograms of leftovers that feed a surprising array of wildlife.
Researchers tallied up how much carrion polar bears produce each year by partially eating their prey and ditching the rest on the sea ice. The study, published in Oikos, estimates that these bears supply about 7.6 million kilograms of marine mammal remains annually across their range — enough to power a whole network of scavengers through the harsh northern winters.
Holly Gamblin and her colleagues drew on decades of observations to spotlight this overlooked role. Polar bears specialize in ambushing seals on the ice, but they’re picky eaters. They gobble up the energy-rich blubber first, often abandoning the muscle, bones, and other bits before finishing the whole carcass. That leaves a bounty for opportunists, especially during spring when bears are in a feeding frenzy to bulk up for leaner months.
The team crunched the numbers using known kill rates: an average polar bear takes down around 43 seals a year, totaling about 1,001 kilograms of biomass. But with their fat-focused diet and habit of moving on quickly, rarely caching or defending kills, about 30% become available scraps. Scaled up to the global population of roughly 26,000 bears, that’s a massive 7.6 million kilograms, or the energetic equivalent of 39 million megajoules.
This isn’t just free lunch; it’s a lifeline in the extreme Arctic, where food swings wildly with the seasons. Carrion acts like a buffer during shortages, bridging the marine and terrestrial worlds. Seals, hidden underwater most of the time, are tough for land animals to access — until bears haul them onto the ice and crack them open.
Eleven species are confirmed regulars at these feasts, from nimble Arctic foxes trailing bears for scraps to flocks of glaucous gulls and common ravens picking at remains. Arctic foxes, in particular, rely heavily on this boost, especially when their usual rodent prey crashes. Other visitors include wolves, snowy owls, and even grizzly bears venturing onto the ice. Eight more birds and mammals, like wolverines and eagles, are likely joiners based on their scavenging habits elsewhere.
The setup is unique to the frozen sea: cold temps preserve carcasses like a natural fridge, extending their shelf life for weeks or months before the ice melts and dumps leftovers into the ocean. But it’s fragile.
As Scholander et al. (1950) noted: “It is quite obvious that the Arctic mammals are adapted to withstand cold or they would freeze to death.”
Climate change adds urgency. Warming is shrinking sea ice, forcing bears ashore earlier and cutting their hunting time. Declining bear numbers could slash carrion supplies, rippling through to foxes, birds, and beyond, potentially destabilizing the ecosystem.
Citations: OIKOS. DOI: 10.1002/oik.11628
