In the Slater Museum there is a bird that appears to be Spizella breweri
taverneri, heavily and darkly streaked above, more gray than buffy below,
and with a wing chord of 62.5 mm. It is from 20 mi. E Moxee, Yakima County,
15 April 1953. Lots of S. b. breweri were collected at the same locality in
other years. I can't imagine this bird could have been picked out in the
field as different, although in the specimen drawer it is quite
distinctive. Presumably birds of this form migrating through Washington
wouldn't be sitting on top of a sagebrush singing so would be even less
likely to be identified. It will be very interesting to discover what is
different about the songs of the two, although--as Gene Hunn
wrote--Brewer's seems so variable anyway.