COLUMNS

It’s snowing — Who’s happy and who’s not?

Steve Lekwa

It’s snowing as I sit down write this morning. The ground is covered, but there’s barely enough to sled on. Maybe there will be enough by this afternoon, and that might make some kids happy. It might also make snow clearing businesses happy, since the season has offered them little work so far. The rest of us humans might rather see dry roads, no salt and mild temperatures continue until spring.

Snow is a mixed bag for the wild world. The “happiest” little critters are probably mice, voles and shrews that spend their lives scurrying around in little tunnels and runways under tall grass.

A nice blanket of snow helps to insulate their world as it protects them from harsh winter winds and the watchful eyes of many kinds of predators. They can still find the seeds and grass clippings they use for food pretty easily under the protective cover of snow. Shrews and small hunters like weasels can hunt their prey in a more protected world, where they’re less likely to become prey themselves.

Larger prey like squirrels, rabbits and ground-feeding birds are placed at a greater disadvantage since they stand out more against a pure white background.

Deeper snow, on the other hand, allows rabbits to reach the more tender bark higher up on trees and shrubs.

I hunted rabbits in my younger years and still would today, except that my wife, Sue, has decided she doesn’t like to eat rabbit very much. I looked forward to days like today with good “tracking snow.” I could follow a rabbit’s tracks right to its hiding place in a tuft of grass or a brush pile and pretty much know that the bunny was there somewhere just off the end of those tracks.

Ground feeding birds like pheasants, turkeys and all those wintering ducks, geese and swans can still grub around through newly fallen snow to find waste grain, as long as the snow doesn’t get too deep over the harvested fields, or worse, get a covering of ice.

Waterfowl would just relocate a day or two’s flight farther south to where they could again find adequate food.

Pheasants and turkeys can’t migrate and just have to work harder to scratch their food out of the snow cover. They are often forced to travel farther from safe cover to places where wind has blown the fields more clear of snow or to road shoulders, where vehicles add to the dangers already posed by aerial predators.

Wintering songbirds are less affected by snow. They can’t scratch through much snow, but most of their natural foods — like weed seeds, dried berries, and insects hidden in tree bark — can be found above the snow.

Aerial predators that depend mostly on small prey like mice are forced to work harder when snow to hides their prey. Hawks have tremendous vision for detecting movement and some ability to see in ultraviolet wavelengths.

Mouse urine glows in ultraviolet light. Though testing has shown that the ultraviolet advantage is small, it may help them at least prioritize their hunting to areas with greater mouse activity when snow cover isn’t too heavy. Owls don’t benefit from ultraviolet light, but they are adept at detecting motion even in very dim light. They supplement great night vision with extra acute hearing that helps them locate mouse activity they can’t even see. Larger owls may shift to hunting larger prey like rabbits, opossums and even skunks when snow makes them more visible.

Mammalian predators use several senses in their hunting. Smell is, perhaps, their most powerful tool for finding prey when they can’t see it. Smell carries with the wind for some distance and is left behind wherever prey animals have been. Invisible mouse runways can be detected under snow, and following those runways hopefully leads to mice. Sound comes in next. A fox may make their diving pounce on a mouse they can hear under even a foot of snow. Good night vision with acute ability to detect motion is an asset for both predators and prey. Deeper snow hinders larger animal’s ability to run, and a rabbit might detect an approaching fox or coyote in time for their speed and ability to run on top of snow to allow them to escape. Acute vision helps the hunter find even mice when snow cover is light, and takes over as the primary sense when a predator has to run down that fleeing rabbit. Snow hinders and helps, but our native wildlife is adapted to live with it.

Steve Lekwais the former

director of Story County Conservation. Contact him at 4lekwas@midiowa.net.