Calgary's winter population of geese and other birds getting bigger — much bigger

The annual Christmas Bird Count shows there more birds, including bald eagles, sticking around the city in the winter than in previous decades.

Christmas Bird Count shows an increase of nearly 700% for Canada geese over 30 years

Canada geese winter population way up 0:45

If you're near the Bow River at sunset, you're usually in for a show, as thousands of Canada geese and other water fowl return from a day of scavenging in nearby grain fields just outside Calgary city limits.

But are there more birds, including bald eagles, sticking around the city in the winter than in previous decades? The annual Christmas Bird Count says yes. A lot more.

In 1987, the annual count, done on a single day between mid-December and early January, recorded 1,406 Canada geese. Thirty years later, the count done last month recorded 11,145. That's an increase of 693 per cent.

And with an increase in Canada geese, a jump in bald eagles follows.

Three bald eagles were counted in 1987. Last month's count revealed 34. That's a jump of more than 1,000 per cent.

A biologist and author says climate change is part of the reason for these increases.

"That is one of the factors," Birds of Alberta author Chris Fisher told CBC News.

"If you look at the overall trends, we are having some warmer winters, although we do have some cold stretches as we just went through a couple of weeks ago. But certainly, overall the winter conditions are slightly warmer but also we have a little bit more industrial discharge into the river that's keeping it open as well."

A biologist and author says more Canada geese are staying in Calgary during winter months, due in part to climate change. Another factor is a greater industrial discharge into the Bow River, which creates more open water surface area due to less freezing. (Mark Matulis/CBC)

That industrial discharge keeps parts of the Bow River from freezing, more than in the past, which provides greater open water surface area. Canada geese return to the river each evening because it's a safer environment, free of predators like coyotes, Fisher said.

"All told we have close to 25,000 water fowl, ducks and geese, hanging out in the open water during the winter time," he said.

"It is not freezing over as much as it was 30 years ago."

With files from CBC's Mark Matulis