Birds dive for food despite sub-zero temperatures On the upper
Chena River in the heart of a cold winter, a songbird appeared
on a gravel bar next to gurgling water that somehow remained
unfrozen in 20-below zero air. Then the bird jumped in,
disappeared underwater, and popped up a few feet upstream. The
bird continued snorkeling and diving against the current of the
stream, which is so far north that in December direct sunlight
never touches it, instead bathing only the tops of spruce trees
with a ruby light. Soon, two other dark birds with bodies the
size of tennis balls landed near the other. Bending from their
knees, they bobbed up and down and then all three jumped into
the stream. It seemed crazy behavior for a cold winter day, but
swimming is how American dippers make their living, even here in
Alaska, where they range as far north as the Brooks Range. Mary
Willson, a biologist, ecologist and consultant from Juneau,
might be the only Alaska researcher who has studied the American
dipper. She has pulled