By Sarah Locke
Special to the News
Last summer, researchers headed to Herschel Island expecting to confirm a trend already documented in many northern regions. But after tramping the length and breadth of the island, peering into burrows and taking extensive notes, they came up with some unexpected good news: the Arctic fox seems to be holding its ground on Herschel against competition from red foxes.
With their luxuriously thick coats and compact bodies, Arctic foxes are well adapted to the severe tundra climate. But larger and leggier red foxes have been steadily moving north for decades and taking over the habitat of their smaller cousins. In Scandinavia Arctic foxes are already endangered, and the few that remain have been pushed into marginal terrain by red foxes.
“On Baffin Island the red fox was absent before 1918, but has invaded all of the eastern Arctic since 1918,” says Dominique Berteaux, a professor at the Université du Québec in Rimouski who is overseeing the Herschel research.
Berteaux has studied Arctic foxes for many years on Bylot Island in the eastern Arctic, where they used to have a cornucopia of eggs laid by breeding snow geese pretty much to themselves. Now red foxes are moving in, and there is a predictable outcome when that happens.
“Red foxes will chase and pursue Arctic foxes and kill them,” he explains.
Berteaux is one of the lead investigators on a project referred to as Arctic WOLVES, which stands for Wildlife Observatories Linking Vulnerable EcoSystems. This circumpolar initiative, developed for the International Polar Year, is looking at how climate change affects tundra ecosystems, now and in the future.
Red foxes have been present in the northern Yukon for more than a century, so there was every reason to think that these superbly opportunistic animals already would be thriving in the rapidly warming western Arctic. But researchers found that they are still scarce, both on Herschel and the mainland.
Last summer Daniel Gallant collected data for his doctoral dissertation on the ecological interaction between red and arctic foxes on Herschel. He and other researchers walked transects 500 metres apart across the entire island, looking for all signs of fox activity. They located about 60 dens and holes, but red foxes were not raising young in any of them, and only two dens had litters of arctic
As many as seven Arctic fox dens have been found on the island in years with abundant prey, but last year was not one of them as lemming numbers were low. Snowy owls, which also feed mainly on lemmings, failed to raise any young.
The researchers also flew over parts of the northern Yukon which had been surveyed in the past. When they spotted an active den, they landed and snuck up on it, listening for the sounds of kits barking inside. They found three dens with young Arctic foxes inside, but no dens with litters of red foxes. Similar numbers were recorded when the area was first surveyed 38 years ago.
“Basically it looks like even though there is a milder climate, some other things have not changed to the point that the red fox can really thrive. Since it is a predator it might have something to do with the abundance of prey; red foxes are larger and need more prey,” says Gallant.
No conclusions can be drawn on one summer’s worth of data, but climate change is not the only theory that Gallant wants to test out. He and other researchers also will dig through fur trade records from about 300 posts across northern Canada, looking for information on fox harvests, and changes in the ratio between red and Arctic foxes.
“The Arctic fox is easier to catch than the red fox,” he explained, adding that severe over-trapping of Arctic foxes in Scandinavia probably reduced their numbers even before competition with red foxes began taking its toll.
Another theory is that red foxes may have followed humans north, taking full advantage of garbage dumps and other debris around settlements; some might have followed the coastlines, eating the carcasses of marine mammals killed by sealers and whalers.
“Where you have human activity you have new predictable sources of food,” says Gallant.
Arctic foxes travel over the pack ice in winter, scavenging food from kills made by polar bears and also digging seal pups out of dens. The researchers want to see whether red foxes do the same, or whether they head south in winter.
When Gallant returns to Herschel next summer, he’ll continue surveying for dens, but also hopes to fit satellite collars on both red and Arctic foxes to track their winter travels. “We especially want to see what they do when the going gets tough in autumn and winter when there are not many prey.”
For more information, contact Professor Berteaux at firstname.lastname@example.org or Daniel Gallant at email@example.com.
This column is co-ordinated by the Northern Research Institute at Yukon College with financial support from Yukon Department of Environment and Yukon College. The articles are archived at www.taiga.net/youryukon