A “severe” but not unprecedented die-off of wild horses on Sable Island last winter reduced the herd by about 25 percent.
Parks Canada estimates that 150 horses died on the remote sandy crescent in the Atlantic Ocean, about 290 kilometers southeast of Halifax. That’s more than double the annual average.
Sable Island ecologist Dan Kehler says horses are most vulnerable in late winter, when their energy reserves are lower and grass is harder to find.
“They carry a parasite load and in the winter there’s not a lot of forage for them. So those factors, along with cold, wet and windy weather, can create some challenges and lead to mortality,” Kehler told Breaking:.
He says there have been die-offs of similar size in the past, but the Sable Island National Park Reserve’s horse population has continued to grow.
“That’s really the best indication of what the consequences of those past actions have been. But there are certainly some impacts on the genetic structure of the horse population. So you probably lose the weaker individuals, but, again, there are less opportunities for reproduction. for the rest,” he says.
Record population ‘correction’
The number of horses on the island varies.
Last year, the population reached 591, the highest number ever recorded.
“I would consider this a correction,” says Philip McLoughlin, a biologist at the University of Saskatchewan who has studied Sable Island horses for years.
“It’s not unusual for wild populations to suffer declines, sometimes severe ones, especially this population that has had a well-documented history of going through periods of stable growth and then declining. It’s completely expected,” McLoughlin told Breaking:.
He says 30 foals were born this summer and he doesn’t feel the herd is threatened in any way.
Since 2007, a university team has been naming and tracking the life histories and movements of every horse on Sable Island.
The fittest animals probably survived.
Last month he returned from an annual field study on Sable Island.
He says the herd is where it was about eight years ago.
“I would say that one of the things we might expect when we look at who survived is that these are probably the fittest individuals. The ones that might be less inbred are the ones that survive. We still have to look at this and it will be several years before we see how this could have developed.”
Parks Canada took over management of the island in 2013, although Sable Island’s horses were formally protected in 1961 following a public outcry over a plan to ship them off the island to become work horses or sell them for food.
Today’s Sable Island horses are believed to be descendants of animals that the British confiscated from the Acadians during their expulsion from Nova Scotia in the late 1750s and 1760s. A Boston merchant and shipowner who was paid to transport The Acadians to the American colonies also left some horses and other animals on the island.
Now Ehler says the horses are being monitored, but otherwise must survive on their own.
“Horses are considered a wild species, so they are protected like any other species under Canada’s National Parks Act. So, in general, we let natural processes occur on the island just as we would in another national park” .