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Red Fox Expansion Causing Problems On North Slope

As the winter approaches, many animals are migrating south, but there’s one sly creature that scientists say in recent years has started to remain in the high Arctic in the winter. Red foxes have not only expanded their habitat into the far north, the charismatic, bushy tailed mammal is out-competing the native Arctic fox and causing problems at oil field dumpsters in Prudhoe Bay.

Wildlife Biologist Garrett Savory says the red fox is indeed wily, curious and sly.  

“It’s a jack of all foxes. It’s highly adaptable. It’s been found in many habitats: anywhere from wildness conditions like here in the boreal forest in Interior Alaska all the way to living in suburban London,” he says.

Savory studied the Red fox as part of his master’s thesis at the University of Alaska, Fairbanks Institute of Arctic Biology. He says red foxes didn’t move from the northern foothills of the Brooks Range to Prudhoe Bay until the 1980’s. In the last decade, he says red foxes have started to overwinter there. Now, they are beginning to out-number smaller, shyer counterpart, the arctic fox.

“The one aspect that has changed is there’s been more people moving into the Arctic, mostly for resource development. In Alaska, oil,” says Savory

Savory says scientists believe red foxes have been able to utilize the Dalton Highway as a travel corridor to move north. He says they may have scavenged on garbage left by travelers.

“Also, hunters use the Dalton Highway to access caribou, and they could possibly scavenge off the gut piles form caribou hunters," he explains. "In addition, there’s the [Sagavinirktok] River and that’s an excellent corridor as well, that goes right straight from the Brooks Range to Prudhoe Bay.”

But how foxes managed to survive the frigid Arctic winter remained a mystery to Savory. So, he decided to capture both red and arctic foxes for tissues samples to find out more about their diets. A stable isotope analysis shows both species rely heavily on human sources of food in the winter. Landfills and dumpsters at Prudhoe bay are made to keep large animals like bears out, but Savory says a small, sly fox can squeeze under fences and through holes in dumpsters.

“One day in Prudhoe Bay in early May, which is still winter up there, I counted seven red foxes," says Savory, "all within a short period of time and this was just casually looking. I wasn’t looking hard. So, they really know the landfill is a good food source and they know dumpsters are good food sources, you see tracks all around there.”

Savory’s study shows human food waste makes up nearly 49% percent of the red fox diet on the North Slope in the winter. In arctic foxes, 39% of their diet can be attributed to anthropogenic sources. Data also show the arctic fox has a more varied summer diet, relying on a  combination of small animals and bird eggs, where as the red fox depends almost entirely on lemmings for food in the summer.

“The red fox is less efficient with the food," explains Savory. "The Arctic fox picture is like a Prius and the Red fox is like a big old Cadillac. It just needs more food to get by.”

The presence of the red fox could have dire consequences for animals like the lemming, but it could also cause problems for oil field workers’ safety.

“Then you also have disease dynamics. Rabies is a naturally occurring disease in the Arctic fox population and with red foxes moving in to these areas, it’s not known how they will affect the spread of rabies.”

But Savory says there is a solution.

“It would be great if they could reduce garbage access to prevent wildlife from accessing it," he says. "They could do that by keeping it in inside or incinerating it. And not only red foxes and arctic foxes are suing it, but there are also glaucous gulls and ravens are accessing it as well.”

Savory’s research was published in the Journal of Canadian Zoology last spring. Funding came from the National Science Foundation, UAF’s Institute of Arctic Biology, BP Exploration In corporate and the Alaska Department of Fish and Game.