Trash helps red fox outfox arctic kin

 

Meghan Murphy
907-474-7541
06/02/14

fox on a pipe 3

Photo courtesy of Garrett Savory
Red foxes have made their way to Prudhoe Bay, feeding on human food waste in Dumpsters and the landfills there.

Recent arrivals to the Prudhoe Bay oil field have been causing trouble for the locals — eating their food and taking over homes that have been in the family for generations. The invading red fox may look post-card cute, but biologist Garrett Savory, a recent graduate of the University of Alaska Fairbanks, cautions they are sly, cunning and riding on the coattails of development in the Arctic.

Savory suspects the chicken wing falling shy of the Dumpster and the rejected macaroni cascading over landfill trash have drawn the red fox north, where the immigrants may threaten the smaller, resident arctic fox.

He recently published a study in the Canadian Journal of Zoology that shows about half of the Prudhoe Bay red fox diet comes from human food waste each winter. Arctic fox have also taken to dumpster diving, as 40 percent of their winter diet is human food waste. Summer diets were healthier, with both species eating more “fast food” like scurrying lemmings.

Just as a fox follows its nose to the food, Savory followed the fox to their food source — Dumpsters and a landfill that were secure against polar bears but not against the adept and sly red fox.

snow block set 1

Photo courtesy of Garrett Savory
Garrett Savory, a recent UAF graduate, builds a blind out of hand-fashioned snow bricks during his study of red fox in Prudhoe Bay. He took tissue samples from red and arctic fox to ascertain how much of their diets were coming from human food waste.

Savory undertook the study while a master’s student with the UAF Department of Biology and Wildlife and the Institute of Arctic Biology.

“I’m particularly interested in how wildlife takes advantage of our manipulation of the environment,” Savory said. “I also wanted to continue the work of my late adviser, Professor Erich Follmann.”

To ascertain the fox diets, Savory used stable isotope analysis on blood and hair samples from live red and arctic fox and bone samples from donated red fox carcasses. Human food has a certain chemical signature, a stable isotope signature, that becomes incorporated into an animal’s hair, blood and bone, with each representing a certain time period in the animal’s life.

A fox’s winter fur, which grows in September and October, reveals food intake for late summer; blood samples from late spring reveal food intake for winter; and bone taken from carcasses reveals food signatures over as many as seven years, though a typical fox lives only a couple of years.

After first being observed in Prudhoe Bay in 1988, red fox have taken over the majority of arctic fox dens in the area, which are considered prime real estate in the flat and treeless coastal plain. Savory noted that arctic fox often dig dens in pingos — hills of ice carpeted in earth — and these dens are reused for decades.

Although red fox have spread into arctic regions elsewhere in the world, they have not yet expanded into other parts of the coastal plain, but that might change if garbage isn’t controlled.

arctic fox pair(1)

Photo courtesy of Garrett Savory
About 40 percent of the arctic fox winter diet in Prudhoe Bay comes from human food waste. Although Savory thinks there might be enough food for both arctic and red fox in Prudhoe Bay, there does not seem to be enough housing. Red fox are taking over arctic fox dens, which are typically in pingos, mounds of ice carpeted in earth.

“There’s going to be an increase in development in the Arctic and availability and access of anthropogenic (human) food will increase,” said Savory. “Development companies want to be as low impact as possible, and understanding how to manage their garbage can help.”

If better precautions are taken in Prudhoe Bay to keep red fox from eating garbage, he said, their numbers might diminish and allow the arctic fox to reign once again.

“In other cases where garbage was controlled, the red fox survival rate plummeted,” Savory said, noting that red fox probably need the supplemental food source to survive the winters.

Savory said companies and people need to ensure that food makes it into the Dumpster and that the Dumpster doors and gates to the landfill are closed. Fencing needs to be hole-free, and fence skirting could prevent animals from burrowing underneath it.

With all these precautions, it might just be possible to outfox the red fox.

ADDITIONAL CONTACTS: Garrett Savory, gasavory@alaska.edu

ON THE WEB:
Garrett A Savory, Christine M Hunter, M.J. Wooller, Diane M O’Brien. “Anthropogenic food use and niche overlap between red and arctic foxes in Prudhoe Bay, Alaska.” Canadian Journal of Zoology.

Rosen, Yareth. “Study: Red fox conquering the North Slope thanks in part to human food.” Alaska Dispatch.

 

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