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All photos courtesy Dennis Ellison, Nisqually NWR Volunteer. These photos were taken in 2005. |
I was out for clouds on Wednesday morning, completely happy with just the clouds. Until a volunteer pointed out the snowy owl, sitting on a hummock out in the estuary, bout 100 yards north of the trail. Once I saw the owl through the spotting scope, I couldn't take my eyes off this beautiful bird of the tundra--the Arctic tundra, the dry, frozen, treeless land between the northernmost forests of Alaska and Canada and the icy Arctic Ocean. Using an online "as the crow flies" mapping tool, I figured this snowy owl could have flown about 2000 miles to Nisqually from a randomly chosen tundra location--Atqasuk, Alaska. Distances to other areas of the tundra would be comparable. Incredible.
Snowy owls are adapted to spending the entire winter on the tundra, but not all snowy owls spend every winter there. Some regularly migrate in winter to southern Canada, and the northern US--the plains, New York, and New England, notably. Once every four years or so, winter irruptions bring snowy owls much further south--to the Pacific Northwest and even as far as California, Texas, and Florida.
Irruptive behavior is linked to the food supply and, in the case of the snowy owl, this means lemmings, a year-round resident of the tundra. Lemmings are rodents that dig vast networks of tunnels beneath the snow where they survive the harsh winters by eating plant roots.
Snowy owls pick off lemmings when they emerge from their tunnels for fresh air. An adult snowy owl will eat three to five lemmings a day; a breeding male will spend hours catching dozens of lemmings to pile up in front of a female he is courting. If the female accepts him, they will fly off together, the overjoyed male may catch another lemming and pass it to his mate with one foot in mid-flight.
In a boom lemming year, the snowy owl may raise a dozen chicks, feeding them up to 2000 lemmings before they can hunt on their own.
After a 4-5 year cycle of successful feeding and breeding, the lemming population reaches a peak and soon deplete their food supply. Yes they panic. Yes they become hyperactive. Yes they run across the tundra in all directions (and once in a line stretching 30 miles long). Yes they drown trying to cross large rivers. They are desperate, and behave like proverbial lemmings. Exposed, the lemmings are either hunted or starve, and their population crashes. This starts a chain reaction through the tundra food web. Snowy owls are forced southward in search of new sources of food.
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| Two snowy owls perched on snags at mouth of the Nisqually River. |
So, the snowy owl I was seeing--likely a juvenile male, according to the refuge biologist--was likely exhausted and starving. Nisqually is abundant with food sources for the owl, but the owl has at least two things going against it. There are numerous birds of prey at the refuge competing for the same food: while I was watching the owl, I spotted bald eagles, a harrier, a red-tailed hawk, and possible a kestrel (the birders out that morning recorded 71 species, so I know there were more raptors out there). And, because snowy owls hunt on the tundra, the biologist tells me, they are not adapted to hunting where there are trees or other obstacles. They face the ground when they hunt for lemmings and so may crash into buildings, barns, trees, and other large objects while hunting in our landscape.
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| In the absence of lemmings, snowy owls will prey on small mammals and birds including rodents, rabbits, squirrels, songbirds, water fowl, wading birds, and...oh no...alcids. That could mean marbled murrelets. |
Does one snowy owl an irruption make? No, but the birding community is all a-flutter with online postings about snowy owls right now. Earlier this week, snowy owls were spotted in Washington State in Douglas and Okanogan Counties as well as at Ocean Shores; owls were reported in Oregon--one at the airport; birders posted sightings in Minnesota and Michigan and a whopping 100 were spotted in Wisconsin. You can go to a recent irruption map to see how widespread the irruption is this year.
You can also go out to Nisqually. The snowy owls might not be there, but I guarantee something wonderful will be.
