Eagles have nested in southeast Calgary's Carburn Park for years, and regularly draw local birdwatchers for glimpses of the bird of prey.
However, it appears a prominent eagles' nest in the park was taken over recently by Canada geese.
And in a twist, birdwatcher Diane Stinson told CBC News that the geese were dive-bombed by a couple of eagles that seemed perturbed at their presence last week.
"There were these two mature bald eagles flying, and they charged right at the nest," said Stinson, a member of Nature Calgary and leader with the Friends of Fish Creek Provincial Park birding group.
"The geese flew up and took off down this side channel and the bald eagles were chasing them."
'Everybody was pretty riveted'
Stinson has been birdwatching for nine years. She said she has witnessed eagles go after all kinds of birds — from flocks of mallards to gaggles of geese — but never in a nest.
"It was pretty amazing. We had a group of 10 people … and everybody was pretty riveted, seeing this occur," Stinson said.
The confrontation left her with plenty of questions: Did the geese aggressively force the eagles from the nest? Were there eagle eggs in the nest? If so, are they still there? Still viable?
After all the effort the eagles went through to build the nest, only to apparently lose it to Canada geese, has naturalist Brian Keating asking questions, too.
"I've never seen anything like that before, and I wouldn't have thought it possible," Keating said.
"It just goes to show that geese have very, very strong personalities, and they are very big and very aggressive."
Still, eagles are capable of killing a Canada goose, Keating noted.
Melanie Whalen, the director of animal care at the Calgary Wildlife Rehabilitation Society, did not see what happened. But she said if Canada geese did kick out the eagles, it was a courageous act, and more likely occurred when the nest wasn't in use.
"It's not common that waterfowl would take over an eagle's nest, but geese are opportunistic in finding a nesting site," Whalen said.
For Stinson, at least, incidents and rarities like these keep her birdwatching.
"That's the joy of being out and birding, and just being in nature," Stinson said. "You see exciting things almost every time you're out."