American Dipper

Ever since 7 July 2019, when we observed an immature American Dipper in the cascades of the Deschutes River in the Tumwater Falls Park, we have looked for another. On 25 October we finally succeeded. This latest dipper is also a young bird, judging by its pale bill. The scalloped back feathers indicate that it is newly molted. (The white feather is miscellaneous down.) In the second photo you can see white lines on the bird’s eyelids. According to Kingery and Willson (2019), these feathers produce the white flash that you often see when you watch dippers. I had always thought these flashes are caused by their nictitating membranes blinking.

I suspect dippers are year-round residents on this sea-level stream, perhaps augmented by mountain birds moving to lower elevations when their streams freeze in the winter. Dippers inhabit cascades, even nesting behind waterfalls and feeding under water. I am surprised they do not have even larger toes help them swim in the rapids or to hold on to the slippery rocks upon which they forage. To survive this environment, they have low metabolic rates and their blood can carry more oxygen than other birds. Their feather coat is thick. In Arctic Alaska they have overwintered at tempetatures below -50 degrees Celcoius (presumably near salt water).

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