Have you seen a Snowy Owl this winter by any chance? This winter is being marked as an extraordinary year for Snowy Owl sightings. Not just in Iowa but across the nation! In a winter such as we have experienced in 2011-12 with very little time that our landscape has been white, it has been much easier to spot these beautiful birds which are almost snow white as mature adults and white with brown or black spots in younger birds. This has been described by some experts as one of the most significant wildlife event in decades.
Over my 33 years in Grundy County, I have had reports of Snowy Owls more winters than not. But with that said, let me clarify that they are rare in any kind of numbers. The white, two-foot-tall birds that live in the Arctic the rest of the year, are known to fly south in large numbers every few winters in what is known as an irruption. This year, the numbers are unusually high.
I checked Birds in Iowa by Kent & Dinsmore to find that the largest number of Snowy Owls reported in a single winter was 277 during 1976-77. This winter's event will surely blow that number out of the water.
Immature Snowy Owl.
In checking the Cornell Lab of Ornithology website, I found Snowy Owl reports all the way south into Oklahoma with one being reported in South Texas!
In the frozen landscape of the arctic tundra, the Snowy Owl's fate is often tied to the abundance of lemmings. In years when lemmings are scarce, Snowy Owls may not even attempt to breed. The clutch size is commonly two or three, but it appears that in years of plentiful food (lemmings) the clutch size will increase to seven and even all the way up to twelve.
So, if an abundance of their favorite food, rodents and lemmings in particular, yielded the large clutches, why are they down here this winter? The population boom causes overcrowding and competition at typical wintering grounds pushing inexperienced birds farther south. The majority of those being seen are younger owls, mostly males. Another theory among some ornithologists is that lemming populations crashed recently after the boom that could have led to the push south, but researchers have not confirmed such a decline. Lemming populations do cycle through dramatic highs and lows which traditionally have contributed to past Snowy Owl irruptions.
Experts report the owls are often found malnourished and in poor health from these extended migrations. Here in Grundy County, there have been two Snowy Owls turned in to our department. Both were immature birds in poor condition.
In my research for the article, I learned that for a nest, the female scrapes out a patch of turf, or bare ground with her feet. In the unlined nest, she lays her eggs. The male helps with nesting. Pairs will fiercely defend their nests against predators, even wolves.
Snowy Owls enjoy a variety of alternate names so I'm including a few for you here: Snow Owl, Arctic Owl, Great White Owl, Ghost Owl, Ermine Owl, Tundra Ghost, Ookpik, Scandinavian Night-bird, and Highland Tundra Owl.
So, while weather-wise we have not experienced much of the white stuff, the winter of 2011-12 will go down as an exceptionally Snowy year.