One consolation to the dreary wet weather of winter is the occasional appearance of a Varied Thrush. These are birds of the shadows, nesting in mature forests of the Coast Range and Cascades. In winter, they move to lower elevations, where they rummage through the leaf litter looking for insects.
Along with a flash of pumpkin orange from their bellies, Varied Thrushes reveal themselves through their odd song. Like other thrushes, Varied Thrushes produce sounds consisting of two pitches at once. This polyphony is made possible by the syrinx, the birds sound organ, located at the branch of the trachea. Since each branch has its own membrane, multiple pitches are produced at the same time. The result is a single buzzy tone, often described as ethereal (or just eerie).
I saw my first Varied Thrush in a back yard in Ohio. While it is always fun to see a vagrant, I much prefer seeing Varied Thrushes in Oregon, either in the deep forests in summer, or in the winter gloom of my Portland yard. Perhaps it is in their native gloom that these colorful thrushes shine brightest.