The bald eagle – America’s national bird – is a hyper-aggressive piece of biological machinery. A phenomenally effective bird of prey found all over the contiguous US, they build massive nests weighing up to 1 tonne (1.1 tons), soar on thermal convection currents at 70 kilometers (43 miles) per hour, and fight to the death with competing birds and even members of their own species.

They are not what you would call particularly altruistic – so when some Canadian birdwatchers spotted a breeding pair of bald eagles sharing a nest with a baby red-tailed hawk, along with three of their own eaglets, they were surprised to say the least.

Located at the Shoal Harbour Migratory Bird Sanctuary in British Columbia, the parents are tending to their adopted fledgling and their own offspring equally, and experts are trying to work out why this notoriously selfish species of predatory bird is welcoming the unusual newcomer to their nest with no apparent benefit to themselves.

Speaking to the Vancouver Sun, a retired raptor scientist by the name of David Bird – nominative determinism for the win – suggests that one of the raptors, during a raid of a hawk’s nest, may have initally taken the youngling as food but then adopted it instead.

“My guess is that this little guy begged loud and hard for food – not even thinking about the danger,” he told the Sun. “Food overrides everything in these birds. He begged away and mom and dad said, ‘OK, here’s an open, gaping beak. Let’s put food in it.’”

Speaking to The Dodo, the founder of the Hancock Wildlife Foundation – an initiative designed to promote conservation and wildlife science to the general public – has a similar theory.

“I think the hawk was picked up by the eagles as potential food and brought back to the nest,” David Hancock explained. “That’s not an unheard-of event.”

The fact that it hasn’t been eaten is because the baby hawk is similar enough in appearance to the eaglets that it deceived the adoptive parents into feeding it instead.

“The hawk is not being browbeaten. There’s no sibling rivalry. The eaglets are kind of nice to it,” Hancock added, stressing that it’s “unbelievable” that the familial relationship is so placid and non-aggressive.

Bird also told the Sun that within just a week, the young hawk will be independent and sizable enough to leave the nest itself – so it may get away with the ruse before the bald eagles consider it a threat or a fattened-up dinner.

In any case, we think Pixar has found the plot to its next movie.

[H/T: The Dodo]