I am reading Three Among the Wolves by Helen Thayer, who is best known for walking and skiing to the North Magnetic Pole accompanied only by her husky, Charlie.
In a subsequent trip, she and her husband spent nearly a year observing the behavior of three wolf packs in three different parts of Canada. This question is about the pack observed on the ice of the Beaufort Sea, to the northwest of Tuktoyaktuk, in winter. (In spring, the wolves move back to land.) This pack of wolves scavenged off the kills of polar bears. As Thayer says:
Polar bears, the primary hunters, killed the prey [the seals] and then ate mostly the fat. Wolves and foxes then shared the meat.
According to the National Geographic Society's article Scavenger, scavengers are the janitorial staff of the ecosystem:
Scavengers play an important role the food web. They keep an ecosystem free of the bodies of dead animals, or carrion. Scavengers break down this organic material and recycle it into the ecosystem as nutrients.
But even more startling than wolves as scavengers, was the incident Thayer describes -- wolves as recipients of the largesse of a polar bear:
...The bear thrust his head into the seal hole...He hauled out a thrashing seal, crushed its head, and without stopping to eat, walked to the edge of the ice and stared into the water. The three wolves....[rushed] to the body.
The bear ate none of this kill.
On reading the first quote, I postulated that the bear ate only the blubber because it was more efficient to capture another seal, rich in blubber, than to pick at the meat; the wolves were simply filling a niche by scavenging the bear's leftovers, as were the arctic foxes who also followed the bears on the ice.
But it is harder to explain the bear's behavior in the second quote. This seems like pure altruism on the part of the bear (which seems unlikely), or an isolated incident. So, my question:
Has this "altruistic" behavior been reported in other sources for polar bears -- or for any large predator with respect to scavengers -- and if so, what benefit does the polar bear (or other large predator) gain from it?
Addendum: Possibly pertinent fact prompted by comment by @Chris H: The pack of wolves on the sea ice numbered eleven, one of whom had an injured paw. There were at least six polar bears nearby. The wolves waited respectfully for the bears to leave their kills before darting in.