Get to know the critters who inhabit the snow

YOU’RE OUTSIDE ON a beautiful winter day enjoying the cool, crisp air.

A hard light reflects off the diamond field of snow. Ah, winter. Looking closer, you see something smudging the white carpet that fell a few days ago. What’s that? It’s covered with… pepper?

Actually, they’re wee bugs commonly called snowfleas. On a warmish winter day, take a look around the base of a tree where the snow is hollowed out a bit, or in the melted snow in boot or ski tracks. If you look carefully, you will often see tiny, black dots on the snow that resemble ashes or finely ground pepper. Those little specks are moving because they’re alive, but the snowfleas’ name is a misnomer.

They are not really fleas at all, they’re springtails. Achorutes nivicolus are minute wingless insects less than a millimetre long that love to swarm in enormous numbers on older snow. They cause no harm, so don’t hesitate to take a good look at them. Their tiny dark gray or black bodies absorb solar radiation to keep warm. They hop around on the snow by means of a unique springing device called furcula, which extend from the tip of the abdomen and fold forward along the underside.

Snowfleas spend most of their inconspicuous lives among pine cones and needles on the forest floor where they eat spores of fungi, bacteria and algae, and help break down organic matter. They are most evident when they move over the snow’s surface on mild winter days. They are not well known, yet they’re very abundant – you can often see them in the melting snow in your lawn, or at the end of your driveway! Snowfleas, in turn, provide food for very small carnivores like mites, spiders and insects, some of which also dwell under the snow in forest leaf litter. In turn, birds

that hunt on the snow surface eat these diminutive predators.

If you think winter kills off all of the mini-beasties until spring arrives, think again; that thick layer of white stuff lying all ’round is teeming with life. Look over there. See those little footprints in the snow? Perhaps you’re lucky enough to see a small brown blur dashing across the snow and ducking into a hole. Mammals like mice and voles that are too small to grow thick winter coats will often live under this “snow coat” to avoid freezing. It’s like living in an elongated igloo.

While the wind howls and temperatures fluctuate on top of the snow, the world just half a metre below the surface is moderated, with temperatures sometimes 30 Celsius degrees warmer than the air above. The warmth comes from deep within the Earth. That heat is trapped under the snow and creates a space where animals can move about.