I recently traveled west from Bottineau on Highway 5 around mid-morning. By the time I got to the Highway 14 turnoff to Kramer, I had seen four snowy owls. Most of them in the first half of the 11-mile stretch. I have not kept records of my snowy owl observations per mile, but that has to be some kind of record.
I did a quick internet search to learn if an irruption is occurring this winter, but that came up empty. As many of you know, snowy owls are a species of the tundra. But like many other birds (and some North Dakotans) they often head south for the winter. Some range maps show their winter range covering the tundra-northern coniferous forest ecotone southward across much of Canada and into the northern border states.
So we generally see a few each winter. But they are also known to move in masse southward during winters in search of food when the populations of their main prey item, lemmings plummets. Historically the lemming population cycled in 3-4 year intervals, which made predicting those irruptions quite predictable.
Some of you may recall that an irruption of snowy owls in the United States during the winter of 2011-2012. The birds came down in force, making national news, with several sightings well south of their usual destinations. That irruption was different. It was caused, scientists discovered, not due to a low lemming population, but because of an unusually successful breeding season. Young males could not establish territories in their usual breeding range, so they wandered southward in search of a suitable territory.
There is some evidence that the cyclic nature of the lemming population may be a thing of the past. Some lemming populations in northern Europe have not been exhibiting the characteristic 3-4 year cycle since the mid 1990’s. One of the factors scientists are investigating is a change in snow. Not the amounts, but the type, or structure, of the snow.
The arctic is cold. That would be expected to produce dry, soft snow, which falls to the ground and forms a blanket on the vegetation above the ground, leaving an open space between the ground the big white blanket above in which the lemmings could spend their winter somewhat protected under the cover of the snow. But these days the temperatures are a bit warmer, the snow a little wetter and heavier. The space between the ground and snow cover above that helped the lemmings thrive during the winter may be gone. It will be interesting to learn what the scientists continue to discover, and how this may change the lemmings, snowy owls, and the tundra ecosystem. In the meantime, there are a few snowy owls in the state this winter, so be on the lookout for them as you travel about.
~Chuck Lura
