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Photo by UWGB student Nick Walton

Great Gray Owl (Strix nebulosa)

Great Gray Owls (Strix nebulosa) are the largest owls in North America (24-33 inches tall). They are, as their name suggests, gray in coloration, with brown mottling on the body and a white throat patch. These northern owls have large round-heads, with a black-edged facial disk, yellow eyes and a yellow bill. The tail is long and extends beyond the folded wings. Great Gray Owls prefer to hunt in the open and often feed during the day, so they are easier to find than some of our night-feeding owls.

Although Great Gray Owls are usually only seen in boreal forests of the far north, from the northern US Border to Hudson Bay, your chances of seeing them this winter have greatly increased. Many owls have been seen at Wisconsin Point near Duluth, MN and Superior, WI. People are seeing as many as 20 owls in an afternoon. In fact sightings of Great Grays are up all along the northern border of the US from Michigan throughout the Northwest. Over 1300 owls were observed in Minnesota on a recent count. Great Grays are reluctant to fly over water so they are less likely to move into WI across Lake Superior, so WI will see fewer birds. Some bird experts believe they may be found in WI as far south as Horicon. Expect to see them until February, when they will return north to nest. A few birds appear to nest regularly in northern Wisconsin, while larger numbers occur in northwestern Minnesota.

Great Gray "invasions" into southern Canada and sometimes into northern United States occur on about a 4 year cycle in response to changing prey abundances (Cheveau et al. 2004). The owls' preferred prey are voles (up to 80% of their diet according to a recent BLM report) as well as other rodents. Voles are subject to large fluctuations in population size that rise and crash in response to changes in vegetation and predator densities. A current hypothesis suggests that specialist predators like Great Gray Owls are responsible for fluctuations in vole populations (Hudson and Bjornstard, 2003). When vole populations decline the birds roam farther south in search of food, often into the Great Lakes States. This year birds are roaming farther south than before.

In an article in the Milwaukee Journal, birding experts remind people wanting to see owls to stay in their car and shut off the engine and to get no closer than 75 feet. Too much attention and noise is stressful for these birds and interupts their hunting behavior.

More information about Great Grey Owls

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Last updated on April 15, 2014