The owl invasion
Poor prey populations to our north have brought owls to our area in search of food
Marshall Helmberger
M. Helmberger
Success. A great gray owl finds a meal.

An invasion of owls typically arrives on silent wings, so it’s easy to overlook unless you’re paying attention. But this year, the influx of northern owls in our region is pretty tough to miss, at least when in comes to the huge numbers of great gray owls that have turned up in recent weeks in search of prey. A poor cone crop in central Canada has affected species in many ways. Conifer seeds are one of the foundations of the boreal forest food chain, and so a poor crop impacts small mammal populations, among other things. That, in turn, sends the birds that prey on small mammals looking elsewhere for sustenance— and in recent weeks, that’s been right here in our backyard.

Besides great gray owls, significant numbers of tiny boreal owls are also showing up in the area, although they can be much tougher to spot. For one thing, they’re small— about the size of a 20-ounce bottle of pop. The great grays, by comparison, are the largest owls in North America. Boreal owls are also pretty strictly nocturnal, while the great grays hunt during daylight hours and frequent field edges and roadsides, making them easy to spot.

What we don’t know for sure is whether the owls are finding much prey here, either. While the DNR no longer has a staff to conduct regular small mammal surveys, Tom Rusch, area wildlife manager in Tower, says anecdotal reports suggest the populations of mice and voles are down here as well. So far, the DNR has had a few dead owls turned in, seven or eight of them boreal owls and about two or three great grays. Rusch said starvation was the likely cause of death.

Occasional periods of starvation are a routine fact of life for many predators, including owls, so this winter isn’t particularly unusual, except the hungry owls have suddenly turned up in our backyard.

While these northern owls are more commonly seen here in winter, they aren’t just winter visitors. All three of the northern owls, great grays, boreals, and hawk owls, are all known to nest in northern

Minnesota, although numbers can vary quite a bit from year to year.

Typically, following an invasion year like this one, more of these owls will opt to remain in Minnesota during the summer, so we could well have some of these birds around for quite a while. I know I’ll be on the lookout…

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I'm glad the owls came down from Canada. A few years ago when they came down, they cleaned up a population of snowshoe hares that had grown too large. Hopefully, they will cull the herd again. They do cast a striking pose when you see them roosting in a Popple or White Pine. Time for me to pull the spotting scope out and attach the camera.

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