Laura Erickson's For the Birds

Owls

According to an old legend, when someone sees an owl, it foretells a death. This year, thousands of great gray owls have descended upon Minnesota, Wisconsin, and North Dakota from the boreal forests of Canada. Sadly, the deaths they seem to be foretelling are of the owls themselves. The mouse population is at a record low in many areas of their normal winter range. It’s apparently been low for many months, because virtually all of the great grays caught in banders nets or picked up after being found killed by cars have been adults. Normally the first owls to leave their northern haunts are the young of the year, so it seems clear there was very little reproduction this year.

Every four years or so, great gray owls and northern hawk owls stage a cyclic irruption in northern Minnesota, which coincides with the cyclical mouse and vole populations. But the magnitude of this year’s invasion is unprecedented. Some birders have found over 70 different great grays and 50 different northern hawk owls in a single day of birding. There have been a great many sightings of great gray owls in Duluth, Minnesota, where I live, even in the heart of downtown.

The great gray owl is perfectly designed for hunting mice and voles in open bogs of the north. Although in inches this is the largest owl in North America, it weighs less than half of what a snowy or great horned owl weighs. Its huge wingspan allows it to plunge into deep snow or into tall meadow grasses to mice hidden beneath, using its large wings to pull out again. Its claws are very long, giving it the wide aim it needs to catch much of its prey without ever seeing it, but its talons are thinner and weaker than those of owls designed to catch ducks, grouse, and rabbits. Great gray owls tend to perch on the very thin outer branches of trees, and they are so light that the branch barely bends under their weight.

When hunting, great gray owls are an amazing study in concentration. Their huge facial discs gather and focus even the tiniest sounds in their capacious ears—they can hear a mouse when the mouse is buried under 18 inches of snow. Unfortunately, their focus on finding prey is so unrelenting that they seldom notice anything else around them. When they take off in low, lumbering flight, they are often hit by cars. I suspect that statistically, great gray owls are more likely to be killed by cars than any other North American raptor.

As of this writing, I’ve had the extraordinary good fortune to see four different great gray owls in my own backyard. The first, on Christmas Eve, was sickly looking—apparently quite hungry—and so I defrosted a mouse for him, since I just happen to keep a supply of organic white mice in my freezer for my education screech owl. The moment I set the mouse in the snow, he swooped down and devoured it. But neighborhood crows sent him on his way before taking handouts became a habit.

So far in January, three more great grays have turned up in my yard while I’ve been looking out the window to notice. My neighborhood is hardly proper habitat for them, so most of the birds and squirrels around here have never seen such a thing. I can tell when an owl is near because my normally-abundant squirrels disappear. If the owls repel squirrels, they attract little birds–so far I’ve watched crows, blue jays, pine grosbeaks, a cardinal, and dozens of chickadees gathered around my backyard great grays, scolding them. A swarm of chickadees around an owl’s face isn’t much of a bother except that their calls alert more aggressive birds like jays and crows. And the crows are not only annoying—they dart at a sitting owl’s face and jab at its head. When crows discover a great gray owl, the owl is faced with a dilemma If it stays put, the crows will continue harassing it, often for many hours. Crows are especially infuriated to see yellow eyes, and if the owl closes its eyes for a long time, sometimes the crows will get confused and leave. But how can the owl trust that when it closes its eyes they will leave, rather than jabbing at it when it’s helpless to take evasive action? And if the owl takes off in hopes of finding a more private hunting or roosting spot, many of the crows will pursue it and set off a whole new group of birds mobbing it.

Thanks to the huge number of owls, these kinds of dramas are playing out in backyards all over northern Minnesota and North Dakota right now, and as the owls deplete their prey up here, more and more of them are heading farther south, providing a great many people with opportunities to see these fascinating and beautiful birds. But this movement is bringing more and more great gray owls to inhabited areas where they continue to be hit by cars. Slowing down, and limiting our driving during low-light conditions, could help, but few people are willing to modify their driving habits for birds, and it’s dangerous for a handful of people to drive significantly slower than the rest of traffic, so cars will continue to take a huge toll of owls. It will take several years for these magnificent birds to recover their numbers after this difficult season, but the natural rhythms of Nature promise that the population will eventually bounce back.