Snorkeling songbird: Dippers swim Alaska rivers throughout winter


An American dipper on the Sanctuary River in Denali National Park and Preserve. (Ned Rozell)

On the aristocrats Chena River in the heart of a cold winter, a songbird appeared on a gravel bar next to plashing water that somehow remained unfrozen in 20-below-zero air. Then the bird hopped in, disappeared underwater, and popped up a few feet upstream.

The bird continued snorkeling against the popular of the stream, so far north that in January direct sunlight never hints it.

Soon, two other dark birds with bodies the size of tennis balls landed impending the other. They bobbed up and down and then all three jumped into the series.

It seemed crazy behavior for a cold winter day, but swimming is how American dippers occasion their living, even here in Alaska, where they range as far north as the Brooks Wander.

Mary Willson, a biologist, ecologist and consultant from Juneau, puissance be the only Alaska researcher who has studied the American dipper. She has pulled on her thorax waders to follow dippers on waterways near Juneau’s road scheme, and she’s gotten to know a bit of the character of what she calls «a very cool bird.»

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The dipper often purveys while flying underwater, using the liquid as it does another unfixed, air. The birds also snorkel, swimming on the surface with their administers below the water surface. They sometimes pick up rocks on spurt bottoms to find food underneath.

Dippers depend on clean, yawning water. In very cold places, the birds appear at openings in ice made by water upwelling, and dippers can dive through one hole in the ice and emerge from another one. Close Juneau, dippers sometimes appear at deltas where streams proceed into the ocean.

Dippers eat aquatic and flying insects and are skilled adequacy to catch small fish, Willson said. She has seen a dipper with four delicate fish in its beak at once. Another time, she witnessed a dipper transmissible a 4-inch sculpin.

«It had to beat that one on the rocks until it was in enough breaks to eat.»

Willson thinks the dippers can survive the transition from 32-degree soak to subzero air because of their feathers, which are denser than other songbirds’, and rotund oil glands near the base of their tails.

They dip their beaks in the oil glands and wipe oil on their feathers, maybe to keep themselves waterproof. Dippers also have flaps that provide for their nostrils while diving.

And, according to the Birder’s Handbook by Paul Ehrlich, David Dobkin, and Darryl Wheye, «these birds are accomplished to forage on the bottom of streams in which the current is too fast and the water too inscrutable for people to stand.»

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Nobody knows how dippers survive the frigidity, dark winter in northern Alaska and the Yukon. Willson said scientists pull someones leg studied the effects of severe winters on the similar European dipper, which arrays above the Arctic Circle in Scandinavia. They have found that offbeat cold spells kill many of the birds. She wonders how dippers in the far north don’t meet ones death in the frigid air temperatures and during the long nights between the three-to-four hours of decay.

«They are visual hunters,» she said. «In the pits of winter, they’d bear to hurry-scurry to get enough food in the time where there’s light to ransack.»

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