Friday, May 14, 2010

American Redstart

Today I banded two after-second-year male American Redstarts.  Redstarts have an uncommon molting pattern.  After they hatch, they molt into a plumage that is very similar to females (see bottom photo), except that the males have a slightly orange tinge to their yellow sides.  The males remain in this plumage through the following breeding season (their second year), after which they molt into their distinctive black and orange plumage.  They retain this new plumage the rest of their lives.  Thus, the next spring, black and orange birds are older than two calendar years.
I wish I were better at working with Photoshop.  I'll have to admit the photo above was manipulated--I erased my hand, which was holding on to this bird's feet.  I think the photo is, nevertheless, rather intriguing.  On the next photo, notice the bristles at the base of the bill.  Birds with rictal bristles can usually be predicted to feed on flying insects.  However, when researchers taped down rictal bristles, the birds' flycatching abilities did not diminish.  Placing birds in wind tunnels, ornithologists discovered that the bristles protect the flycatchers' eyes from the birds' prey and other airborne debris (Handbook of Bird Biology: Cornell Laboratory of Ornithology).
I took the following photograph of a female American Redstart last year near Dundas, Minnesota.  Note the yellow sides.  A first or second-year male would have a much deeper, almost orange tinge to his sides.

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