Cross posted from the Great Beyond
Let us get one thing clear right at the start: lemmings do not commit mass suicide by leaping off cliffs into the sea. However, their populations do undergo massive size fluctuations, leading to mass migrations where the cute critters may go swimming to find new food sources.
At least, they used to undergo massive population explosions. In a paper published this week in Nature a group of researchers analyse the absence of such events since 1994. The culprit, you guessed it, is climate change.
Nils Stenseth and colleagues show that changes in winter weather and snow go hand-in-hand with changes in Lemmus lemmus populations. They further show that when the regular explosion of lemming numbers doesn’t occur predators such as foxes switch their attention to other species, leading to knock-on effects throughout the eco-system.
“A relatively small effect on one particular species is having a broad effect on the system,” Stenseth, a researcher at the University of Oslo, told Reuters.
In a News and Views piece analysing the research, Tim Coulson and Aurelio Malo, of Imperial College London, explain that lemmings like to scurry about in a gap that warm ground melts between it and the snow layer above it. This so-called subnivean space is relatively warm and keeps the rodents safe from things that would like to eat them.
What Stenseth and colleagues found was that climate change seems to have eliminated the subnivean space and, worse, created a sheet of ice over the moss on which lemmings like to nibble.
“The critical reader will complain that the story is based on correlations. Although this is true, it is often the only way to study populations and the consequences of changing climate for ecosystems,” write Coulson and Malo. “The collection of detailed long-term data on the dynamics of free-living populations of animals and plants rarely attracts the same excitement as genomics or particle physics, yet such data are vital in characterizing the consequences of climate change for the natural world on which we depend.”
Climate pushing lemmings to cliff – BBC
Now It’s Serious: As the World Warms, Lemmings Take a Hit – Newsweek
Image top: Forced out of flooding snow tunnels, a Norway lemming stands its ground as winter comes to an end.
Image lower: The face of defiance. A Norway lemming tells the photographer that, whatever their size differences, it will not give in without a fight.
Images by Erika Leslie / captions by the paper authors