Better news for loons as some areas see increases

Populations in New England on upswing, while Canada, midwest states stabilizing

While we are stuck at home and worried about the future, there is no better time to remind ourselves of the wonders of spring. In today’s Science of Spring, let’s look at growing optimism for the future of our much-loved loons.

For years one of North America’s best known loon experts has been reaching the grim conclusion that loon numbers are declining across his study area, a large chunk of Wisconsin that is very similar to our own region.

This spring Walter Piper of Chapman University has had a change of heart.

“I sometimes dwell on the negative,” he admits in a recent blog post for the Loon Project, which he runs.

Only a few months ago, Piper wrote that “the inexorable nature of the (loon population) decline — the fact that the numbers have been slipping downwards steadily for the past two decades — implies that some relentless, slowly-worsening environmental factor has been at work that reduces the abundance of small fishes in northern lakes and will continue to do so in the coming decades.”

But recently he has been working with a team of loon biologists revising the common loon account for Birds of North America, a standard reference in bird science.

He says this has given him “a broader, more balanced view of how loons are doing along the southern edge of the species range. This has turned me around.”

“The picture of loon breeding in other parts of the U.S. is quite a bit rosier than in northern Wisconsin. While not all of the data are reliable, there seems no question that loons are thriving in Maine, New Hampshire, Vermont and Massachusetts, having experienced double-digit increases in adult populations in the past decade,” he writes.

“These findings contrast sharply with Upper Midwest loon populations, which have shown little or no change. In Minnesota and Michigan, according to our latest measures, populations are merely stable. Wisconsin loon populations, while they increased greatly during the 1980s, 1990s, and even early 2000s, have been measured as stable or declining in recent years.

“So the overall picture of loon populations along the southern edge of the breeding range is mixed. But things look so good for the species in New England that, even after considering the slightly negative recent trend from the Upper Midwest, we must conclude that overall the U.S. loon population is doing fairly well.”

It is very unlikely that extra loons from eastern North America will move west to fill up the gaps there, Piper said. Loons always return to the region where they were born and even to a lake that is similar in size and water chemistry (such as acidity) to their “natal” lake.

“Still, the mere fact that loons are reproducing well and expanding their population somewhere is heartening. It suggests that factors causing the decline in the loon population in Wisconsin might be local ones, not sweeping ones, like climate change.

“Or it might mean that factors that could lead to loon population declines — whatever those factors are — can be reversed by intense local conservation efforts, such as occur in New England states.

“At any rate, I am looking at the world a bit more cheerily now after learning about thriving loon populations in New England. With my tunnel vision always focused more on things loon than things human, there is reason for hope.”

Dave Evers of the Birds of North America team offers a note of caution: “When I contacted colleagues in Canada, there are relatively no new monitoring data, including for Eastern Canada,” he said.

“I do worry about the loss of thousands of adult loons to botulism type E in Lakes Erie and Ontario each fall. The annual loss has been happening for over a decade now, and from our band returns they are mostly from populations in Ontario and Quebec.”

Still, Ontario and Quebec together have around 350,000 loons: more than half of the 611,000 to 638,000 loons in North America, the latest census from Birds of North America says.

A footnote: Officially our bird is called the common loon. There are other loon species as well. The Cornell Lab of Ornithology is a marvellous source for all of them — photos, videos, recorded calls and maps. tspears@postmedia.com twitter.com/TomSpears1