Around this time of year, snowy owls are known to migrate south of their summer ranges near the Arctic, with many showing up all over the continental United States. In November, the first snowy owls of the season were reported in Seattle, and we'll soon see if snowies start popping up all over the country as they did last year.
The huge increase in snowy owls heading south that happens every few years is a process known as irruption, and is partly a factor of their population. Snowy owls feed mostly on lemmings, and during boom years female snowy owls lay as many eggs as their caloric intake can support. That population explosion pushes down lemming populations, which leaves snowy owls spreading all over the northernmost regions of this hemisphere in search of food.
And spread they can. As explained in this great video by the Cornell Lab of Ornithology, some of the snowies have been tracked flying from Alaska, through Canada, and into Russia. Others, the video notes, can be found hundreds of miles out on the (disappearing) sheets of pack ice in the Arctic Ocean, searching for food. Credit to Cornell's Gerrit Vyn, who shot the video and does the majestic creatures justice.
Last year was a stunning year for snowy owl sightings in lower hemispheres, one that even saw them popping up in Hawaii. Cornell is running a crowdsourced tracking project called eBird with the Audoubon Society that's tracking the snowies to try to gain insight into why they're coming south in large numbers. It's unclear at this point, but it's likely that they're finding less food in the Arctic, as snowy populations have long been expected to be in decline. Still, if you see one this winter, enjoy the sight while you can.
Follow Derek Mead on Twitter: @derektmead