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Amanda Stephenson
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Ranchers and wildlife officers have known for years that pronghorn antelope are migrating animals. But until researchers started collaring them and tracking their movements, no one knew the kind of incredible journeys these animals were capable of — or the impact human development could have on them.
The study is a collaboration between the University of Calgary and various other partners in Alberta, Saskatchewan, and Montana. From 2004-2007, researchers captured approximately 24 pronghorn does each year and fitted them with GPS collars.
Dale Eslinger of Alberta Fish and Wildlife — one of the project partners — says one of the initial reasons for the study was that in 1995, an exceptionally cold winter led to a massive die-off of pronghorns.
“We lost over half the herd in the province,” Eslinger says. “In the next period of 10-plus years, we saw a fairly slow recovery in numbers and we were surprised by that, given the fairly mild winters we’d experienced.”
The collaring project was meant to give scientists more information about this species, but the news of their migration habits surprised everyone. Some of the animals were traveling distances of 800 kms, all the way from Montana to Lloydminster.
“We knew they migrated, but nobody really had a sense of the distance they migrated,” says Mike Suitor, a U of C graduate student who worked on the project.
The study also had some implications for the Medicine Hat area, which has traditionally been a major migration corridor for pronghorns on their south-north journey. However, the study showed the animals are having an increasingly difficult time navigating through the area. Fences, for example, can be major impediments for pronghorns because the animals aren’t jumpers.
“What we’re suggesting now is there’s so much development in that area that it’s impacting migration patterns,” Suitor said.
The researchers were particularly struck by the animals’ behaviour as they tried to cross the Trans-Canada Highway east of Medicine Hat. Many of the pronghorns would hover at the edge of the highway for days before trying to cross.
“Because of the Trans-Canada Highway, fence lines, and the ever-growing city of Medicine Hat, we can foresee a point when this long-distance migration may no longer happen,” says the University of Calgary’s Dr. Cormack Gates.
This possibility is alarming to scientists. “To maintain healthy herds, we do need to maintain that interchange of animals in a continuum from north to south,” Eslinger explains.
Suitor adds that in very cold winters, pronghorns need to be able to move south quickly. If their migration paths are blocked, they could freeze to death.
“We’re talking mortalities in the hundreds of thousands,” Suitor says.
Project partners hope to be able to work together with municipalities to develop strategies for growth that allow for safe pronghorn migration. These would include things like building fences with room for pronghorns to pass underneath, and designing subdivisions so as not to hamper their movement.
“We’re not saying let’s not develop, let’s not have oil and gas,” Suitor says. “But the Medicine Hat corridor is important for the whole regional pronghorn population. We want to continue development in a way that manages that properly.”
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