That the Black-capped Chickadee might be a recent arrival in the
Pacific NW is an interesting hypothesis. As I recall, the coloration
of the bird here is "dingier" and darker than its midwestern
relations, as are several other species of birds, perhaps for the
camouflage advantage under our dark and rainy skies. If this is the
case, it is possible that evolution by natural selection would have
happened fairly quickly (if we are talking about a relatively short
time frame). I have always wondered why the Chestnuts and Black-caps
come to my feeders together, and seem to occupy such a similar
ecological niche.

Lee Rentz
lee at leerentz.com

>Tweeters,

I've thought that the scarcity of Black-capped Chickadees on local
islands
may be evidence that the Black-capped is a relatively recent arrival
in the
PNW from the eastern forest, perhaps an early harbinger of the Barred
Owl.
Chestnut-backed Chickadees appear more obviously morphologically
adapted to
the PNW habitat. Note also that the Black-capped ranges no further south
than northwesternmost California while the Chestnut-backed ranges
further
south.

Gene Hunn
Petaluma, CA

-----Original Message-----
From: tweeters-bounces at mailman1.u.washington.edu
[mailto:tweeters-bounces at mailman1.u.washington.edu] On Behalf Of Charlie
Wright
Sent: Monday, March 26, 2012 10:22 PM
To: tweeters at u.washington.edu
Subject: [Tweeters] Re: status of Black-capped Chickadee in the San Juan
Islands

Hi Charles,
Thanks for starting this discussion about chickadees, the San Juans, and
eBird.<