Black bear raids eagle nest on military base

American black bears sometimes invade bald eagle nests and chase or eat chicks too young to fly, threatening this raptor population.

A black bear sleeps soundly in an eagle's nest. Photo: FWS — A black bear sleeps soundly in an eagle's nest. Photo: *FWS*

A black bear was caught sleeping in an unlikely place: a bald eagle nest. Researchers came across the sleeping bear while surveying an eagle nest at a military base in Alaska. Black bears ( Ursus americanus ) occasionally use nests built by eagles. This trespassing behavior is threatening bald eagles and their chicks, according to the US Fish and Wildlife Service (FWS), Live Science reported on July 26.

“In the past, only a few eagle nests have been raided by black bears with negative results for the nest owners,” the FWS shared on Facebook. Such incidents often result in the disappearance of chicks.

Bears often eat eggs and chicks in nests, according to Steve B. Lewis, a wildlife biologist with the FWS who directs nest surveys at Joint Base Elmendorf-Richardson (JBER) in southern Alaska. “It’s hard to say how many bears are taking over eagle nests because we don’t spend a lot of time watching what’s happening or have cameras,” Lewis said.

During a helicopter survey in May, researchers discovered a female bald eagle ( Haliaeetus leucocephalus ) incubating an egg in a nest that was later invaded by a sleepy bear. A week later, the egg was abandoned while both the female and her mate were busy nearby. Lewis and his colleagues are not sure whether the incubation attempt failed or if the female eagle simply took a break. Male eagles often take over the incubation of eggs, especially in cold places like Alaska. For that reason, Lewis suspects the nest failed in the spring, long before the bear crawled in.

The bald eagle is Alaska’s largest resident bird of prey, with a wingspan of about 8 feet. The raptor builds the largest nests in North America, some measuring 8 feet wide and weighing more than 4,000 pounds. The giant nests can provide a safe resting place for black bears, who may happen to climb a tree and decide to take a nap.

The scent of fish emanating from the nest may also have attracted the bear. Eagle nests are quite smelly because the fish that the adults catch for their chicks are sometimes left uneaten. According to Lewis, the food is often left uneaten, trampled in the nest, and rotted. Bears have a keen sense of smell, so the bear may have been attracted to the smelly nest.

Bald eagles were listed as endangered in the US in 1978 after their numbers plummeted due to habitat destruction, illegal hunting, pesticides and poison traps, according to the Alaska Department of Fish and Wildlife (ADFG). Thanks to protection and monitoring efforts, they are recovering.

An Khang (According to Live Science )

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