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Spotting Trends

Dave heading out to check nest boxes at Lewes Marsh in the Yukon.

Supporting the future of biodiversity in the North

The diversity of life in Canada’s North is distinct. Yukon is home to plant and animal species not seen in other places, and that’s why Dave Mossop — one of the territory’s leading bird biologists — has been working to preserve and showcase that diversity for nearly 50 years.

“The Yukon doesn’t have a natural history museum currently, and we need these kinds of things to support research over time,” says Mossop. “Museums are extremely valuable and it’s a shame that we haven’t capitalized on it already.”

Mossop and other researchers have been building a collection at Yukon College. So far, it contains roughly 3,000 catalogued specimens. The vision is that the collection will first be open to researchers, and then to the general public as Yukon’s natural history museum.

Public education has been important to Mossop throughout his career. While working for the Government of Yukon, he was the driving force behind outreach programming, such as the Swan Haven public education program and the interpretive program on the Dempster Highway.

In 2018, he earned a Lifetime Achievement Award from the Canadian Museum of Natural History for his work, but he didn’t let the recognition go to his head.

“It was embarrassing, I guess,” says Mossop. “I am one of those people who doesn’t perceive my work as achievements — I’ve basically been pursuing my dream of increasing public education along with my field research.” Mossop came to the Yukon in 1970, lured by an unlikely beacon — the willow ptarmigan.

“I was pursuing a childhood dream — as a very small child I had heard about these birds called ptarmigan in the very far North,” he says. “Growing up down in the south, it was an exotic species.”

A Willow Ptarmigan.

Mossop came to the Yukon and worked as a bird biologist for the territorial government for 25 years before moving to the Yukon Research Centre at Yukon College. There, he has been leading the College’s Biodiversity Monitoring Program for decades.

Through a series of field research projects, many involving student assistance, he has been tracking key indicators of change in Yukon’s ecosystems by monitoring bird species population numbers, reproduction, and general health.

With flies in their faces, Mossop and his research students follow the “turds and tracks,” as he describes it, to add current statistics to the long-term database of bird biodiversity in the Yukon. The database extends back to the 1950s, and Mossop has been adding to it since the 1970s. The historical data is key to spotting trends over time.

Over the years Mossop’s research has focused on using birds, such as the ptarmigan, as indicator species — ones that can show the health of an ecosystem over time. For example, one part of the project focuses on population health of a top predator, the gyrfalcon and its keystone prey, the willow ptarmigan.

“The keystone species are at the bottom of the ecosystem — they are the gasoline that runs it,” says Mossop.

Changes in the populations or health of a keystone species, such as the ptarmigan, can impact the food chain, and affect an entire ecosystem.

In their 2017 surveys on the Chilkat Pass and the Dempster Highway, Mossop and his student researchers found that ptarmigan numbers were fluctuating erratically — a trend that Mossop has noticed since 2010.

In the past, both the falcon and the ptarmigan were locked in stable, reliable population cycles lasting 10 years. When the numbers of ptarmigan flourished, the falcons would lay more eggs and both species would see a time of abundance. But recently, Mossop’s surveys have identified a disruption in that cycle. In fact, in 2012-13 reproduction levels were basically zero.

A Gyrfalcon.

What’s causing these worrying fluctuations? And, are they foreshadowing ecological disaster or merely a short-term blip in the species’ natural cycles?

“It’s frustratingly impossible to tell at this point,” Mossop says. “But the reasons for this potentially troubling finding will form the basis of future analysis.”

After 49 years of work, Mossop was back out in the field again this summer, collecting specimens for the research collection, monitoring changes in bird populations, and adding to his lifetime of research.

“Over the years, hundreds of students have contributed to this work, in the field and in the lab, and there are lots of researchers who could carry on this work when it’s time for me to go fishing,” Mossop adds with a smile.

VIALeighann Chalykoff
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