It’s one of those enduring cartoon myths: Hordes of fur-ball lemmings scrabble from the windswept tundra over some cliff into the sea. Call it rodenticide in response to food stress. Or maybe just a gerbilian version of cabin fever: another critter gone mad during the long dark.
Collared Lemming
Credit: Don Reid/Wildlife Conservation Society
Of course, lemmings don’t commit mass suicide. (This idiotic bit of lore may have originated in a staged scene for a 1958 Walt Disney film called White Wilderness). But the tiny relatives of voles — an anchor of the food chain in far northern ecosystems — do sometimes migrate in large groups during food shortages.
Subsisting on vegetation and seeds and shoots, these 1-ounce to 4-ounce rodents live within the Arctic tundra’s vegetative mat by the uncounted millions, building a maze of raceways and tunnels. Once covered by winter snow, they carve out a subnivian world, warmer than the surface and hidden from most predators.
What happens if climate change builds this snowy ceiling later in the year or removes it earlier in spring? What if periods of melt locks food sources in ice?
Are lemmings poised to rush off the “climate change cliff?” Canadian scientist Don Reid plans to investigate in a project for the International Polar Year.
Credit: Parks Canada
Over the next three years, Reid and a team from the Wildlife Conservation Society will study lemmings and their predators at sites throughout the Arctic, including northern Yukon Territory, Bylot Island and Nunavut. The goal is to find out how the animals respond the changing conditions and how they will fare if climate warming continues to grow.
“We need to know how climate change will affect a variety of resident and migratory predators that rely in large part on these small arctic rodents,” Reid said. “The ability of lemmings to adapt to these changes will have a significant impact on the entire food web, so we need to understand more about lemming ecology within the context of climate change.”
Lemmings reproduce rapidly, sometimes creating chaotic population booms that trigger dispersal. Their sheer numbers (and bite-size packaging) make them a critical source of food for a host of Arctic predators. From the barren-ground grizzly to the agile Arctic fox, from hawks and owls to weasels and wolverines, the lemming feeds them all. Scientists now think predator population numbers might go up and down with lemming fortunes.
So what keeps lemmings fat and abundant? Lots of snow.
A press release from the society explains further:
One of the key ingredients for lemming abundance and productivity is likely snow. Sufficient snow depth insulates the rodents from frigid temperatures, allowing them to devote more energy to breeding and less to avoiding predators.
Later arrival of autumn snows, and earlier spring melts, could subject lemmings to longer periods of sub-freezing temperatures. Also, the tundra is experiencing unusual warm periods in winter, including freezing rain and episodes of thawing and freezing, which can coat much of the lemmings’ foods (sedges and dwarf shrubs) in ice.
Lemming predators also have to adapt to these changes. Predators that specialize on eating lemmings, such as snowy owls and arctic foxes, may suffer if lemmings are no longer so productive.
The study, due to begin next month, will be one part of a large Canadian International Polar Year project called the Arctic Wildlife Observatories Linking Vulnerable Ecosystems (ArcticWOLVES), based at Laval University in Quebec. It aims to tackle food webs throughout the Arctic.