Hello, Birders.
Cara Stiles, in her recent COBirds posting about a leucistic Red-winged
Blackbird at Walden Ponds, Boulder County, asks a good question, to wit:
> OK, so that gorgeous leuchistic Red-winged Blackbird
> is still at the NW corner of Cottonwood Marsh at
> Walden Ponds. I found it (with the added siting of
> Ted Floyd and Lonnie Frye (?) standing way off in
> the distance in the background). What is remarkable,
> is that it's starting to molt and it's bill has turned from
> coal black to yellowish. How does a leuchistic bird molt
> .....once leuchistic, always leuchistic?
First, and most simply, the answer to Cara's question is that all birds molt.
I'm simplifying a bit, but, in essence, all birds molt at least yearly, and
practically all birds in Colorado undergo their complete, annual (or
"prebasic") molt in the summer and/or fall. Even leucistic birds molt. They
molt from one leucistic plumage to another. And so it is with many other birds
that look the same all year long: Black-billed Magpies, Red-tailed Hawks, Song
Sparrows, and so forth. Even though they "look the same" all year long, they
nonetheless undergo an annual molt in the fall. Steve Howell has a note about
this in the September 2009 issue of Birding magazine, p. 14.
Second, and really weird, is that a leucistic bird is *not* necessarily always
leucistic. You might think so, and I certainly would have thought so, but our
own Bill Schmoker recently demonstrated that this is not the case. Here's a
photo essay on a remarkable Steller's Jay that acquired white ("leucistic" or
"albinistic") plumage as an adult: http://tinyurl.com/24wkhoh. Weird! In
particular, check out this photo sequence: http://tinyurl.com/2alsxh6.
Third, I note that Tony Leukering has a great introduction to molts and
plumages in the current (April 2010) issue of Colorado Birds, pp. 135-142. Molt
is a fascinating topic in its own right, but there's also a practical aspect to
it: If you understand molt, your bird identification skills quickly improve.
Check out Tony's "Molt and Plumage: A Primer" and see for yourself!
Finally, it occurs to me that the preceding three points lead us to an
inevitable conclusion: There is so much cool stuff going on within the birding
and field ornithological community in Colorado--people like Cara asking great
questions, people like Bill making original scientific discoveries, and people
like Tony helping us all to understand. Learn more about the Colorado birding
community, and learn how to get involved yourself, by checking out the website
of Colorado Field Ornithologists: http://www.cfo-link.org.
-------------------------------
Ted Floyd
Editor, Birding
Follow Birding magazine on Twitter: http://twitter.com/BirdingMagazine
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