Michael Smith wrote:


>Have we ruled out the earlier thoughts on alternate I plumage? I didn't see
>anything in my books, but my library is limited. I know it sounds weird,
>but what makes sense is two birds, one in adult alternate plumage, one in
>1st-year plumage, both conspiring to confuse us. Anyone have any better
>references regarding Sharp-tailed plumages?

As I have read these Sharp-tail posts I am getting the sense that the
ageing of the bird(s?) is being based on the fact that it doesn't have as
many markings on the underparts as it should based on the guides and
available photos. However this seems to be a misleading way to go about it.
To firmly establish the age of the bird one should look for differential
feather wear rather than colouration. As I understand it, some first
alternate birds will be indistinguishable from a definitive adult; it
depends on how complete the first prebasic and first prealternate moults
were. On other birds one should notice retained tertials or other wing
feathers (coverts etc) and perhaps two different ages of primaries as it has
been reported that some birds moult some of the outer primaries during the
first prebasic moult. Any retained juvenile feathers will look extremely
worn as they may be almost a year old. Retained first basic feathers will be
noticeably more worn than newer first alternate feathers the bird may have
moulted into.
I have been looking at a few first alternate Short-billed Dowitchers
around here and the older retained feathers are really noticeable. However,
there is a catch, some adults of some species do not completely moult all of
their tertials during the prealternate moult, or they do it extremely late
in the spring. You can notice Pluvialis plovers like this and dowitchers as
well as yellowlegs. These birds will also show two ages of tertials, but
less worn primaries than a first alternate bird. Sharp-tailed Sandpipers do
most of their moulting in the wintering grounds, and quite early, so it may
be rarer in this species and probably Pectoral to see adults with retained
tertials in the summer, which may make ageing more straightforwars. I am
guessing on this though.

P.S.- Could someone get that darned Jet Stream set up the right way so that
one of those birds lands nearer to my neighbourhood ;-)
Alvaro Jaramillo
Half Moon Bay, CA

alvaro at quake.net