by Anna Autilio
Lead, Environmental Educator
|VINS Ambassador "Snowy" - Allegra Boverman|
Winter has barely begun, and it is already shaping up to be another Snowy Owl irruption year! These stunning, mysterious arctic visitors will find themselves looking farther than usual for a wide, expanse of hunting ground to pass the winter, delighting those of us who may get a chance to glimpse them before they return to the tundra.
But what is an irruption? The word means an abrupt increase in the natural population of an animal in one area (not to be confused with eruption, and abrupt increase in the amount of lava in an area).
Many animal populations go through cycles of high and low numbers, and the arctic ecosystem is no exception. The lemming, a medium-sized rodent that thrives in the tundra, is also known as the “pacemaker” of the arctic, because of how much their abundance affects other species. In years of high lemming abundance, Snowy Owls tend to lay larger clutches of eggs (he difference between 2 eggs per clutch, and 14), which leads to higher populations of Snowy Owls the following winter.
These owls can’t all inhabit the Arctic together, so some pack a few lemmings for a long journey south, wandering into southern Canada, east and west to Russia and Asia, and very occasionally, as far south as Florida.
|A Snowy Owl nest stocked with 70+ lemmings - Christine Blais-Soucy|
Scientists used to believe that these irruptions of lemmings and owls followed a fairly regular cycle, of every 5-8 years. Seeing as the last noticeable Snowy Owl irruption occurred in the winter of 2013-2014, this seems to hold up, but irruptions don’t occur at the same time everywhere in the country, and there may be no predictable pattern.
According to Project SNOWstorm, which tracks Snowy Owls in the US, most Snowys seen during an irruption year are healthy, efficient hunters; some of them are even fat. This is the general trend, but of course not all of them are so lucky. VINS’s Center for Wild Bird Rehabilitation has already seen two Snowy Owl patients this year, both suffering from severe malnutrition.
Snowy Owls have been popping up all across the landscape of Vermont already, since the end of November: one at the Vermont Technical College in Randolph, another on a bridge in Colchester, a few at Chimney Point, Grand Isle, and even at the Burlington Airport. This individual probably should have chosen a better spot to hunt, and was luckily relocated by VT Fish andWildlife.
|VINS Ambassador "LaGuardia" - Allegra Boverman|
The last major irruption in 2013-2014 saw the arrival of one of VINS’s resident raptors, LaGuardia. This young male owl was found at the airport of the same name, and had broken both of his wings by getting to close to the exhaust from a jet engine. Snowy Owls seem to choose airports as foraging grounds, as they may resemble the treeless expanse of the arctic they are used to.
LaGuardia is now an ambassador for his species, and you can come meet him and his neighbor, Snowy, at VINS next weekend! Join us at VINS on Saturday, December 16th for Snowy Owl Appreciation Day, when you can enjoy owl-themed crafts, meet our flock of education owls, and warm up with hot cocoa and while watching a documentary about Snowy Owls!