(Wiebe; Photo Daniel Dupont; 11 Jan 2017)
Every year Snowy Owls descend out of the Arctic, sometimes in smatterings, sometimes in massive irruptions, to spend winter in southern Canada and the Lower 48 states. They pop up in odd places—hunkering down on haystacks in farm fields, just off the runways at airports, atop light poles in grocery store parking lots—to the delight of birders and Harry Potter fans.
Yet some people feel sorry for the snowies, believing them to be hungry vagrants. Last January, when Snowy Owls were being sighted in Michigan’s Upper Peninsula (as they are every winter), a local TV station reported that the owls’ southern travels were “linked to food supply” and that “Snowy Owls often arrive in Michigan weakened and starving.”
It’s a popular myth that Snowy Owls are driven by starvation to fly south, and according to University of Saskatchewan scientist Karen Wiebe, it’s generally not true. In August Wiebe and her graduate student Alexander Chang published research that showed Snowy Owls wintering in southern Canada appeared to be doing just fine. They found that the average body mass of a wild adult Snowy Owl was 73 percent above the emaciation threshold. Indeed, many of the owls actually put on weight over the winter by increasing their subcutaneous fat stores (fat that accumulates under the skin on birds’ chests and beneath their wings and is used for both insulation and energy).
Wiebe’s findings came from detailed data on the body condition of more than 500 wild Snowy Owls trapped and banded on the prairie near Saskatoon over more than a decade. But the data set wasn’t gathered by Wiebe. She borrowed it from Marten Stoffel and Dan Zazelenchuk, a pair of Saskatchewan owl-banders.