Warming may threaten lemming reproduction

TROMSO, Norway, Jan. 17 (UPI) -- Lemming population explosions may result from breeding all through long Arctic winters and climate change may hit them hard, European researchers say.

Scientists at the University of Tromso trapped lemmings at 109 locations in northeastern Norway to monitor population changes before, during and after a lemming population outbreak, NewScientist.com reported.

As the winter went on, the population of lemmings living under the snow at each site rose, and in the spring the lemming population was large enough to fuel an outbreak, they found.

Researcher Rolf Ims said this suggests huge outbreaks of lemmings are largely driven by their winter breeding abilities, rather than external factors such as food supply or predators.

Lemmings bred fastest at high altitudes, thanks to longer-lasting snow, but rising temperatures due to climate change could see those snow-covered areas shrink, fragmenting lemming populations, Ims said.

Many researchers predict ideal winters for lemmings will become less common, but Charles Krebs of the University of British Columbia says he's not yet convinced climate change will harm lemmings.

What is needed now is a detailed study of lemming populations living under the snow, he says, but he concedes that this is "difficult and expensive" with existing technology.

The study was published in the Proceedings of the National Academy of Sciences.