Bell's Vireo at Kit Carson Park

The endangered California form of Bell's Vireo (Least Bell's Vireo) is a rather dull and non-descript bird. Gray-brown above, paler below, it has a faint split eye ring and two faint wing bars.

It would be hard to find in willow tangles, except that it is nearly the only bird still singing in July and August--all through the heat of the day, too. It has two buzzy phrases, the first rising at the end as if asking a question, the second phrase falling at the end as if answering the question.

Least Bell's Vireo. Escondido, California. August 10, 2018.