Matt Hunter's follow-up with this interesting smallish-looking hummingbird is a
great cautionary tale. Matt shared Julie Edmonds' photo of the live bird with
Shawneen Finnegan and me several weeks ago and both of us concluded that it was
most likely a young Anna's Hummingbird. Over the years, I've seen a number of
paler below, smallish, short-billed immature Anna's misidentified as Costa's
Hummingbirds, thus I am always wary when I see reports of female Costa's. Often
times the only reason given for the ID is that the bird "was too pale below and
looked too stubby and short-billed for an Anna's."
When right out of the nest–and Anna's are essentially year-around nesters in
Oregon–young Anna's are noticeably paler and less greenish-gray below than
adults. They tend to have shorter-looking bills, which if seen close-up have
the growth corrugations that Matt describes in his analysis at the link below.
In my experience, they tend to look shorter-tailed as well, which contributes
to a more scrunched-up or stubby appearance.
As a general rule, the bill of Anna's is straight, while the bill of Costa's is
slightly decurved. Otherwise, if you look at both the text and photos in the
Peterson Guide to "Hummingbirds of North America" by Sheri Williamson, you will
see nearly identical descriptions for the females and immatures of these two
species and although the photos of spread tails show a bit more white on the
tip of R3 in Costa's, the text describes the amount of white on R3 exactly the
same for both species. The differences in the measurements in the table that
Matt created are not likely to be noticeable in the field unless perhaps you
had the two species side-by-side for comparison. For this reason, reports of
out-of-range (i.e. Oregon) Costa's should be accompanied with very high quality
images. There are surely many young Anna's and female/immature Costa's that are
inseparable in the field.
Dave Irons
Portland, Oregon
If you want your voice to be heard, please write to or call your elected
officials,
because they won't know what you want unless you tell them.
---------- Forwarded message ----------
From: "Matthew G Hunter" <matthewghunter@xxxxxxxxx>
Date: Jan 22, 2016 11:11 PM
Subject: Careful with Calypte
To: "ub" <umpquabirds@xxxxxxxxxxxxx>, "obol" <obol@xxxxxxxxxxxxx>
Cc:
I investigate an intriguing female hummingbird:
http://umpquabirds.blogspot.com/2016/01/careful-with-calypte-in-december-2015.html
Matt Hunter
Melrose
