This might be a strange question to ask with so many Snowy Owls being reported in the eastern United States and Canada the last couple of months. One group of birders from Newfoundland counted 301 Snowy Owls in weekend and one Snowy Owl made it all the way to Bermuda! But for those of us in western North America, who are accustomed to seeing Snowy Owls in the winter months, it’s a question we’ve been asking ourselves.
In fact, Snowy Owls have been found this winter in every northeastern state and even in some southern ones. This explosion of owls has excited birders, and even some non-birders, everywhere the owls have been reported.
Here’s a screenshot of all the recent Snowy Owl sighting reported to eBird. It’s hard not to notice the lack of reports from the owls’ usual winter range in northern Canada and Alaska. There are a handful of reports from the west side of the continent but nothing compared to the east side,
Snowy Owls breed in the very northern part of Canada and Alaska where there is constant daylight in the summer, so during breeding season they have no choice but to hunt during the day. In the winter, they hunt by day or night, which is why this species is more commonly seen than other owl species. Snowy Owls mainly eat lemmings, voles, and mice, but they are opportunistic hunters. A Snowy Owl can eat more than 1,600 lemmings in a single year.
Lemming populations fluctuate drastically from year to year with peak number happening about every four years. Lemming populations don’t affect only Snowy Owls, but also Arctic Foxes, Rough-legged Hawks, weasels, Gyrfalcons, and other Arctic wildlife. When the lemming populations are high in the spring and summer, other species’ populations increase; when the lemming population drops, other species that depend on lemmings for prey decline. So goes the cycle of Arctic life.
It seems likely that most of the Snowy Owls being seen/reported in the east are young ones that have been pushed out of their normal range by the adults or have moved out looking for food. This results in an irruption, or an invasion as some birders like to call it. An irruption is a large, temporary migration of a species into areas where they’re usually not found.
This recent invasion is likely caused by a lack of food supply for the owls, following a plentiful supply of lemmings last spring and summer in the owls’ breeding grounds, which meant the adult owls were able to raise lots of young. But this past fall and this winter, the lemming population may not have been able to keep up with the increased owl population, forcing young owls and even some adult birds south and east in search of food.
Last week I asked members of the Alberta Birds Facebook group if they’ve been seeing as many Snowy Owls as in previous years, more, fewer, or about the same. Some members said that they’ve seen fewer owls, and others said that they’ve seen about the same number as in previous years. Unfortunately, I haven’t seen a Snowy Owl yet this winter, so I find myself wondering, where in North America are the Snowy Owls I usually see in the winter. The numbers of Snowy Owls in Alberta are definitely nothing compared to the east.
Here are some photos of a Snowy Owl I took a couple of years ago near our farm,
As a result of the irruption, some researchers have started a project to track the Snowy Owls movements with transmitters. Project SNOWstorm is a really neat opportunity to study Snowy Owls, so please be sure to check out the website and donate if you want to help study Snowy Owls!
More Snowy Owl stories:
:: From the ABA Blog: The 2013 Snowy Owl Invasion: It’s Getting Crazier by the Minute