Wildlife in Canada’s north is increasingly faced with choosing between survival and reproduction. Under the stresses of a changing environment, many animals find it impossible to have both, according to Professor Rudy Boonstra, a biologist at U of T’s Scarborough campus.
He spoke on Monday morning to an arctic biology symposium in Toronto, organized to help rekindle interest in research about the Canadian Arctic. The dominant theme of the event was that wildlife in the far north seems to be suffering the effects of pollution and climate change, but with so little research being funded it is hard to say clearly what is happening.
Boonstra studies how organisms cope with stress. While acute stress can be dramatic, as in the classic “fight or flight” adrenaline scenario, Boonstra is more interested in long-term stresses like food shortage, pollution and abnormal temperatures. Chronic stress causes hormonal changes that help the animals survive, but those same stress responses can inhibit reproduction.
If faced with high stress during the few warm weeks available for mating, arctic animals encounter a harsh choice: survive but fail to breed, or try to reproduce and die.
Wearing his favourite polar bear tie, Boonstra described his studies of two arctic mammals, the snowshoe hare and the arctic ground squirrel. During difficult mating seasons, male arctic squirrels seem to disregard their own health, focussing on mating as often as possible. After the few weeks of summer, the adult males are worn out and “a good proportion die” soon after, said Boonstra. “Males trade off survival for reproduction.”
Snowshoe hares have a different strategy. “They trade reproduction for survival.” When times are tough, arctic hares conserve their resources to survive, and reproduction rates fall.
While they use different strategies, the arctic squirrel and hare populations suffer similar results: their numbers drop following stressful years. And that’s probably bad news for wild populations because pollution and climate change are making life harder in the far north.
Whether those broad climatic trends are actually affecting arctic populations is hard to know. “We don’t have data” about responses to chronic stress caused by pollution and changing climate, said Boonstra. Indeed, most of his own research relies on artificially imposed stress conditions. Even though changes in the Arctic are thought to be indicative of global trends, there hasn’t been the political will in Canada to fund large-scale studies of arctic wildlife.
