Egrets? We have a few...

Posted By SHAWN GIILCK

Posted 7 months ago

Nottawasaga Island has gone to the birds. In the process, it's become the home of Canada's largest nesting population of the southern great egret.

Chip Weseloh, a biologist with the Canadian Wildlife Service, has been on the island periodically for the last month banding birds and conducting a census of the seven colonial water bird species that nest there.

He's found 140 great egret nests, representing a breeding population of 240 birds. Other, non-breeding egrets, might be present in the area as well, representing both Ontario's and Canada's largest population of the majestic white herons.

The other species nesting on the island are the ubiquitous and controversial double-crested cormorant ; great blue heron; black-crowned night heron; herring gull; ring-billed gull and the rare great black-backed gull.

Another surprise nesting bird was a single pair of common ravens, who have taken advantage of the deteriorating condition of the Nottawasaga Lighthouse to rear young.

One young raven was flushed, captured and banded, said Weseloh. The banders knew of the nest in the lighthouse, but were surprised to find a young-of- the-year bird barely able to fly on their first visit earlier this month.

Ravens have migrated south to reclaim some of their former range in Ontario over just the last 25-to-30 years.

Collingwood represents one of their more southern breeding sites, although there have been nestings in Kingston and some other Southern Ontario cities, said Weseloh.

There was also a single great black-backed gull nest on the island, said Weseloh. The black-backed is the world's largest gull, snowy white with a dramatic glossy black mantle. While many of the birds winter on the Great Lakes, very few nest here. Most, said Weseloh, return to the Atlantic Coast and the St. Lawrence River to breed.

The single pair on the island have nested there for the last few years. About 10 pairs nest in scattered locations on Lake Huron. A larger population on Lake Ontario have declined due to botulism poisoning.

Both the great blue herons and night herons are fairly common species that often nest together, and it's not untypical to find great egrets mixing in with them, said Weseloh. However, this is the only colony of its type in Canada where great egrets so dramatically outnumber their cousins.

All three species are tree nesters that build bulky wooden nests that are clearly visible from a distance.

He said his team banded 50 of the egrets during their visit last week.

"They've been relatively stable over the last two years, and have increased dramatically over the last 10 years," said Weseloh. "Ten years ago, there were very few birds there, probably in the range of 10 to 20."

The egrets are primarily common in the southern United States. Like some other now-familiar Ontario birds, such as the northern cardinal and turkey vulture, they've expanded their range to the north dramatically in the last 100 years.

"It's a natural expansion. I'm not sure exactly what the reason is for it," said Weseloh, "but the climate must be amenable to them and similar to what they find down south."

Egrets tend to return to where they were hatched, in a process called "site fidelity,"said Weseloh. That's likely accounting for their rapid increase, all well as the considerable nesting success they've been enjoying on the island.

There are approximately 900 cormorant nests on the island. That's up from 700 just two years ago.

"They're increasing quite quickly," said Weseloh.

The cormorants are a contentious subject with many local residents, particularly anglers who fear they are decimating the fish population. Others are concerned the cormorants are ruining the ecology of the island.

Interestingly, Weseloh said those worries about environmental degradation are largely unfounded.

"You're certainly correct in that cormorants can really disturb the vegetation and kill the trees they're nesting in and the vegetation under it. They have quite an impact. If they kill the trees the herons are nesting in, the trees will eventually fall over and you'll lose all your heron habitat.

"We've had some of that happening on Nottawasaga Island," seloh. "There's a lot of deadfalls on the island, lots of cedars trees have fallen down in the recent past, but I don't think that's because of the cormorants. They haven't been having a great impact on the vegetation yet."

He said the damage looks worse than it is, and some of it, like the cedar dead-falls, can't be attributed to the influence of the cormorants.

"They look like they've been down for 15 or 20 years."

The presence of the breeding birds, particularly the egrets, means the island will remain largely undisturbed for the foreseeable future.