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Isabelle Schmelzer, one of the lead researchers, said the change in climate in Labrador has had a negative impact on the boreal caribou herds. –
By Evan Careen
Climate change is having a significant impact on some of the caribou herds in Labrador, according to a recent study.
The study, led by the Department of Forestry and Land Resources, used climate data over a multi-decade period to look at the survival rates of adult female caribou in five boreal herds in Labrador.
“We found climate changes that have happened in Labrador in the past two decades have, indeed, impacted boreal caribou survival for some populations,” ecologist Isabelle Schmelzer, one of the lead researchers, said. “This changing climate is part of their future as well.”
She said they found a few ways in which the changing climate is having an impact, mostly related to lesser snowfall and freezing rain.
In years where there was more snowfall, there were better survival rates. The reason for that, Schmelzer said, is an indirect benefit through making it more difficult for wolves to hunt.
Years with freezing rain in the fall negatively influenced adult female caribou survival, as well, when the ground does not get frozen and the freezing rains fall on top it creates a sheath on top of the vegetation.
“That can persist the entire winter, as it is insulated by the snow that falls on top, making it impossible for the caribou to reach the plants that are underneath,” she said. “It also can result in the growth of a particular type of fungus which is toxic to caribou. In Scandinavia similar circumstances have led to poisoning of caribou.”
With the climate in Labrador warming over time, she said, these changes impacts could continue to be felt.
Changes in climate aren’t the only factors influencing the decline of the herds, she said. Hunting is having an impact, she said, but can’t account for the declines they’re seen.
“We can’t point the finger entirely at hunting here, in fact our study shows that we cannot,” she said. “However, it did depress adult female survival, which is greatest driver in population trends. Any increase in hunting activity on adult females is going to depress populations.”
Since hunting of the larger migratory herd in Labrador — the George River herd — is no longer allowed, she said she would expect to see more hunting of these boreal herds, which could only have a larger impact.
Another impact was caused by the George River herd, which wintered very far south from 2004-2013, bringing with them more wolves and possibly increased hunting, since it’s hard to tell which herd a caribou is from.
Snowfall has been declining in the ranges of the boreal herds, she said, and data shows it will continue to get warmer in Labrador, with estimates of winter temperatures changing by six or seven degrees over the next 30 years.
Robert Way, a climatologist from Labrador, said in this case there was a perfect storm, of sorts, with the George River herd moving south, bringing enhanced predation, coinciding with a period of a few years of less snow and more rain in the fall.
The dual impacts of the climate warming and enhanced predation make it a less than ideal scenario for the caribou, Way said.
He said since the 1950s there has been a decline of over 40 days of complete snow cover in Labrador and that trend is probably going to continue. He said it may not be perceptible over the short term, but it becomes apparent over the decades.
“The science is becoming clearer and clearer that climate change will have a negative impact on caribou,” he said. “Some populations may manage to stay stable but overall it’ll be rather negative. It’s been an impact over the last 30 years and over the next 30 it’ll be increasingly important of a factor.”