Snowy Owl Migration and Irruptions

ORI's Denver Holt and ORI volunteer Montana Lowden discuss Snowy Owl Migration -

Snowy Owls are migratory birds. But this doesn’t mean the onset of colder temps in the Arctic signals an entire population to move south. Instead, different strategies for different owls still exist.

It appears that Snowy Owls typically migrate during their first year of life - behavior not uncommon to many bird species. This is readily observed during an irruptive year, when large numbers arrive in southern Canada and the Northeast United States. Most of these migrants are typically young of the year.

We also know that not all owls fly south during fall and winter. Most winters, locals inform us that some snowy owls spend the winter hanging around the homes of Utqiagvik. Often, these are adult females. Does this mean that males are the more migratory sex? Or that females, with their large body mass, are simply better equipped to withstand winter’s harsh conditions? Some Snowy Owls can also be found around polynyas, areas of open ocean surrounded by sea ice, and open bays and leads, that attract waterfowl and provide hunting opportunities.

Migration is believed to have a food component, but this does not necessarily indicate a crash in lemming populations, or that food shortage alone drives their movements. Prey may be abundant, but the snow cover just makes hunting more difficult. There is a longstanding myth that irruptions are driven by starving owls. In reality, one of the only things we know with certainty, is that irruptions are indicative of a strong breeding season somewhere in the Arctic, something first proposed by ornithologist of the 1930s and 1940’s. Prey can be abundant and the owls still move south. During the breeding season, Snowy Owls have a highly specialized diet; during the winter, they survive on a wide variety of prey.

There is still so much we don’t know about Snowy Owl migration. Even through satellite telemetry we learn just part of each story. One thing we do know, after spending almost 30 years observing them on their breeding grounds, is that surprises always remain. There is always new behavior to witness, something we’ve never seen before. So many things that leave us scratching our heads. It’s part of what makes the research of these magnificent owls so intriguing, and keeps our work forever humbling.

Remember, if you are lucky enough to observe a Snowy Owl this winter, keep your distance. Migrating and wintering owls have higher energetic demands. Do not make an owl expend this precious resource escaping human intrusion.