BANFF – A goose that fought to take over an osprey nest high up in a tree may seem like a bird-brained idea at first, but bird experts say this goose may not be so silly after all.
Banff resident Lawrence Carter was paddling on the Bow River in Banff National Park last week when he came across a Canada goose high up in a tree with a bird’s-eye view of her surroundings below.
“The first day I thought it was strange but didn’t really give it much thought,” said Carter.
“The second day the osprey arrived back and harassed her for a while, but when she put up a fuss and didn’t seem inclined to move on, they abandoned the nest to the squatter.”
It’s been more than 10 days now since Carter first spotted the goose.
“I’m not sure how well she’s thought this out,” he said.
“How is she eating? If there is an egg, what’s the plan when it hatches? Goose babies are in the water long before they can fly and she’s a long way up.”
Strange as it may sound, there are records of Canada geese setting up home in large tree nests that have been abandoned by species such as bald eagles or ospreys.
Jason Rogers, an independent biologist and eBird editor for much of southwestern Alberta, said nesting in trees is not as uncommon as people may think, noting Canada geese are strong fliers and very agile.
“Nesting in trees is something that likely serves them well in areas that are, for example, subject to early spring flooding or where ground nests are at a heightened risk of predation,” said Rogers, who compiled the 2022 Checklist of Birds in Banff National Park for Parks Canada.
“Soon after the goose eggs hatch, the goslings leap from the nest. They may be a bit stunned after hitting the ground, and the odd one will experience a fatal accident, but they’re durable and can survive falls from great heights.”
Canada geese usually look for nest sites near or surrounded by water, frequently building them on top of raised areas on the edges of ponds or on small islands, including on top of muskrat mounds or beaver ponds. Only females incubate, but males remain close by to guard against predators.
Waterside nest sites are important because as soon as goslings are able to walk, typically within 24 hours of hatching, young geese are led to water where they swim and forage for food.
Nesting season typically begins in April and the geese produce a clutch of between two to eight eggs, with an incubation period of 25-28 days.
Carter said the goose’s partner has been swimming patiently in close proximity to the tree housing the nest, but he does not see a way this ends well.
“I’m more worried about what happens to any potential babies when they hatch as goslings are typically on the water shortly after hatching and long before they can fly,” he said.
Rogers said when Canada geese help themselves to an osprey nest before the ospreys return in spring, it often disrupts osprey breeding for the season, unless the geese get off to an early start and can get their goslings out of the nest before the egg-laying window for the ospreys closes.
“Around here, the first goslings are spotted in mid-May, which means that ospreys arriving in late April can either wait around for a couple of weeks or build a new nest, which may take just as long,” said Rogers.
“But a delay may mean that the ospreys can’t raise as many young, so they may attempt to evict geese from their nests by diving at them. This is sometimes successful, but the geese usually win the battle.”
In some cases, Rogers said the displaced ospreys will skip breeding altogether for the year, maybe reclaiming the nest when the geese are finished but too late in the season to breed.
“This, of course, is part of nature” he said.
