Date: 7/23/17 6:25 pm
From: Nathaniel Wander <nw105...>
Subject: [obol] More about autumnal Tringa molt
In Molt in N American Birds, a Peterson Reference Guide, Steve Howell writes that yellowlegs have two molt strategies, depending on the distance to their wintering grounds:  N/Central American winterers molt before migrating; S American winterers molt after arrival.  Surprisingly, however, Howell's molt classification is very rough-grained and does not mention either suspended molt--molting begun on the breeding grounds, then interrupted until the wintering grounds are reached--or continuing molt--molting ongoing throughout the migration period.
The British Trust for Ornithology's Moult in Birds gives much more detailed descriptions.  Five Tringa species are seen in Britain: Redshank (T totanus); Spotted Redshank (T erythropus); Greenshank (T nebularia): Green Sandpiper (T ochropus) and Wood Sandpiper (T glareola)--they mostly winter in Africa.  The most common of these, Redlegs, breed either in Britain or Iceland, with the Britain-breeding birds initiating molt earlier than the Iceland-breeding populations, which travel farther to their wintering grounds.  This part of the redshank  molt seems much like that Howell reports for yellowlegs.
Otherwise, paleo-Tringa seem to undergo many variations on molt: pre-migratory, post-migratory, begun pre- and suspended during migration, continuing throughout migration.  Members of species, even populations, show variation amongst themselves. Nathaniel WanderPortland, OR
"Don't work towards freedom.  Make the work the freedom."
 
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