People are getting purely blissed out on snowy owl sightings. These beautifully garbed carnivores, with legs booted in plumage and wings right out of a Japanese print, have traveled south from the Arctic in an irruption. What is an irruption, you say, and how is it different from a migration? Well, a migration is a “regular seasonal journey,” such as the annual odyssey of the monarch from Canada to Mexico, while irruptions happen in more capricious ways that are difficult to anticipate. Generally defined as “a breaking or bursting in,” irruptions are ecologically understood as the temporary exodus of a population when the checks and balances of their home environment swing out of control. In this case, the favored prey, lemmings, experienced a population crash, so their predator moved on to greener pastures.
While the wayfaring birds don’t seem to be especially drawn to cities, they do have a fondness for airports, with Boston’s being attractive enough to merit a mention in the New York Times. The airport actually sustains the largest population of snowy owls in the entire northeast. The terrain of Logan is very familiar to the owls, being so like their native Arctic tundra with its long, flat, treeless expanses. And while there certainly aren’t any lemmings in Massachusetts, the airport landscape is filled with delicate morsels such as voles (cousins of the lemming) and rats. For the birds, airports serve as an ideal home away from home, but the owls are large enough (over two feet tall, with a wingspan of nearly five) to pose a threat to aircraft. As a result they are typically captured, banded, and released in a less dodgy area. On occasion they are also fitted with tiny transmitters that allow researchers to map their wanderings.
As long as you live in the United States or southern Canada you should keep your eyes wide open during the next few months – with an owl seen as far south as Hawaii(!!), who knows where you may come across one. If you have already enjoyed an encounter with one of these beautiful birds I would truly love to hear about it in a comment.