(Bjørnar Kjensli/Science Nordic, 23 March 2012) -- A so-called lemming year tends to follow a cold and snowy winter. This is because the small rodents breed prodigiously beneath a good layer of insulating snow. When it melts they appear in numbers. Lemming years provide feasts for predators and many species wait until they can rely on this food supply before having their own offspring. But in barren areas of the far north and higher altitudes further south food for lemmings is pretty scanty.

When freezing weather returns in the autumn the lemmings perish even if they aren’t devoured by predators. This is where the black fruited stink mosses enter the scene. They belong to a moss family that has specialized in getting nutrients from carrrion and animal droppings. One member of the family, Tetraplodon, is called “lemming moss” in Norwegian.

“We who study mosses know that after a lemming year we can expect to find many more interesting lemming and carrion mosses,” says Tommy Prestø, who manages the rock garden and biological station at Kongsvoll, run by the Trondheim Science Museum. These mosses aren’t carnivorous, nor do they have any traps or sticky mechanisms that attract or attach to animals. The moss is of course sedentary plant and can’t search around for dead rodents. But it solves these challenges with the help of flies and other insects. Contrary to most other moss species, the black fruited stink moss doesn’t release spores into the wind. They’ve developed strong colours and scents that entice blowflies and other insects that are attracted to carcasses. “These moss species use flies in the same way catkins or pussy willows attract bumblebees in the spring –the flies move from one moss to another and contribute to the spreading of spores, also to new dead rodents,” says Prestø.

Tagged: News, Polar research: Reports and findings