Interesting plumage

Spotted Towhee

Spotted towhee. Photo by Dan Froehlich.

Despite the unusual rains, we’ve caught some interesting birds.  This Spotted Towhee surprised us at Cash Prairie.  Last year, we didn’t have SPTO at any of our sites, though we detected them regularly down lower just above the Nile Valley.  This juvenile was interesting not just for showing up at 6000′.  As the picture shows, this individual was sporting a mix of juvenile (stripey) and formative (rufous) breast feathers.  What the picture doesn’t show is that this bird had no active molt whatsoever.  That means that it started molting from juvenile plumage into adult-like formative plumage, but then suddenly stopped and suspended its molt.  Perhaps the conditions where it was molting deteriorated and it stopped molting in order to move to a better molting location, in this case up a few thousand feet into the mountains.  If we recapture it, it would be interesting to see if it actually continues its molt where it left off or starts all over again!

Townsend's Warbler.

Townsend's Warbler. Photo by Dan Froehlich.

There’s one pattern that has remained consistent from 2009 to 2010.  While we’ve caught very few warblers this year compared with last year, we’re still finding that adult warblers seem to prefer molting up in the high-elevation meadow (Cash Prairie at >6000′) while the juveniles occur regularly at the lower meadow (McDaniel Lake at around 3400′) as well.  That includes both this spectacular male Townsend’s Warbler as well as this Audubon’s Warbler.  The AUWA presented a bit of a molt interpretation challenge for the bander: after all, its wing included fully four generations of feathers!
See if you can follow this in the pictures: the primary coverts and alula were all juvenile (so grown in the nest about 13 months ago); the three outermost greater coverts and carpal covert were all formative (from last fall, probably in

Audubon's Warbler

Audubon's Warbler. Photo by Dan Froehlich.

August); the inner greater coverts were all from the prealternate molt (thus grown in the spring in April or so); while the inner primaries and primary coverts had just been replaced during its adult prebasic molt!  Pretty cool juxtaposition of four generations of feathers!

Audubon's Warbler closeup

Audubon's Warbler closeup. Photo by Dan Froehlich.

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