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."
Join us on Facebook!