Grey-headed chickadee listed as endangered, climate change a factor

The bird species’ decline is likely caused by climate change

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) updated the status of twelve Canadian animals this month, and it included the Grey-headed Chickadee among the animals newly considered "endangered."

Dr. Louise Blight is the co-chair of the COSEWIC advisory committee on birds.

She said Grey-headed Chickadees live at the edge of the treeline in the Pacific Northwest, and were historically common near Old Crow. The bird is so rare that it is hard to estimate its population, she said.

She said the reasons for the birds' decline are also unclear.

"With many of the species that are assessed, the threats are somewhat clear," Blight said.

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"It could be something like habitat loss, or an unsustainable harvest on the wintering grounds, but the Grey-headed Chickadee occurs in remote areas without those sorts of human threats.

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"It seems quite likely that it's declining because of climate change. We just don't know the exact mechanism, although one plausible threat is the effect of changing freeze-thaw cycles in the winter on their ability to cache food over the winter time."

Syd Canning, a biologist with the Canadian Wildlife Service, has another theory about why these chickadees are struggling.

"There's some concern that part of this decline might be because Boreal Chickadees are moving north because of climate change, and may be pushing the Grey-headed Chickadees out - or even hybridizing with them," he said.

Canning has spent the past 20 years studying species at risk. He says these birds are so rare, they are almost mythical.

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"Any really serious birder wants to add it to their list," he said. "It's always been very difficult to find because it lives right at the edge of forests in Canada and Alaska. It's never near a road, so you have to work really hard to go and find it."

Canning says he caught sight of one in 1983.

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"My brothers and I were working in Old Crow as biologists and we were hitching rides on helicopters going into the Bluefish Caves. We were pretty serious birders back then and the Grey-headed Chickadee was on our mind. So we kept our eyes open and looked at every chickadee bunch we could see. We did see a little family group near Bluefish Caves."

Canning says the last known sighting of a Grey-headed Chickadee Canada was in 2008, or 2009, by Yukon biologist Bruce Bennett.

Thumbnail image courtesy of the Government of Canada.

This article, written by Meribeth Deen, was originally published for CBC Newson Saturday, May 18.