I hadn't seen Gene Hunn's comments when I replied to Mike Smith about his
boreal chickadees in the Wenatchee Mountains, but I subsequently checked
specimens again.

Juvenile chestnut-backed chickadees really do differ from adults in the
direction of boreals. The back and sides are much duller, a medium
reddish-brown, not the vivid chestnut of the adults. The crown is
considerably paler than the dark glossy brown crown of the adult, a dull
medium brown, and might be called "darker than the boreal crown in the NGS
guide." The throat is duller and paler, dark brown rather than very dark
brown (there's not a black feather on a chestnut-backed chickadee!). I
hadn't looked that closely at juvenile chestnut-back specimens before, and
they really are quite different from the adults (which, because of fading
and wear, are a bit duller themselves in midsummer).

I don't know if juvenile chestnut-backs have vocalizations that make them
sound more like boreals; certainly juvenile black-capped chickadees have
some calls that differ from those of adults. I imagine Bent would have
relevant information.

Mike, check the chickadees at the Burke Museum if you get a chance, to see
if they stimulate further thoughts. As much as I work every day right in
the middle of a bird collection, I still find new and wondrous bits of
information every time I look closely at the specimens (support your local
bird collection, all you birders!).

One final important comment: Hal Opperman just pointed out to us that June
5, the date of Mike's observation, seems too early for independent
juveniles at such a high elevation, and he may well be right. Juvenile
chestnut-backs appear in the lowlands in the last two weeks of May, and it
would seem they wouldn't do so until quite a bit later at the rigors of
almost 6,000 feet elevation. I have no further info on the matter, but I
think it does furnish evidence in favor of Mike's identification.

Dennis Paulson