Subject: Gull Molt (was: Gull Training)
Date: Jul 23 17:20:48 1998
From: Michael Price - mprice at mindlink.bc.ca


Hi Tweets,

This thread made me curious; if Defintive Alternate gulls are still in
plumage, what evidence might there be that they've embarked on their
pre-Basic molt?

I had an errand downtown and stopped for a coffee on Granville Island. While
there, I studied the many Def Alt-plumaged Glaucous-winged Gulls Larus
glaucescens panhandling the tourists, both in flight and walking around. The
gulls, I mean; not the tourists--we'll have to wait until the Asteroid Belt
is peopled and civilised before we see that.

On the perched birds: abraded edges, particularly on greater coverts, less
so but still obvious on scaps and tertials; some pale abraded edges on the
longest primaries on most birds, but all were still completely white-headed,
showing no evidence yet of any emergent hood-streaking, barring or clouding
(thanx for a good word for it, DF!).

In flight: some are showing symmetrical gaps in the secondaries (i.e., when
each flight-feather on one wing drops out for replacement, the corresponding
feather on the other wing drops, too, so any aerodynamic impairment to
flight instigated by the absent feathers is lessened by sharing the
additional work equally to each wing). As none of the birds had yet shed any
primaries, this is a sign they've just begun the wing-component of their
Basic molt. Grant says, "Broadly speaking, the moult (note Brit spelling;
see below for instant etymology --M) of the primaries provides the yardstick
by which the progress of the autumn molt is measured." Keep in mind that
autumn begins slightlier earlier in Britain than here, so that its inclusion
as a qualifying adjective could be essentially geographical rather than
intrinsic. Primary molt goes from innermost primary to outermost.

As yet, it seems the gulls have not yet begun to molt body and covert
feathers but the first changes in the flight feathers are just underway, so
it would be accurate to say that these gulls have begun their pre-Basic
molt. It just won't be evident for another little while. This one,
incidentally, is a complete molt-- a comprehensive replacement of head,
body, wing and tail feathers-- for all age-groups in the large gulls except
for this year's juveniles, which will have a head and body molt only,
retaining their flight-feathers until late next summer. These same gulls
undergo a partial molt in late winter/early spring.

The OED gives the term 'moult' (Britain & The Colonies '-), or 'molt' (US),
a rather interesting lineage: Middle English, 'moute' from Old English
'mutian' equiv. to Old German 'muzzon', West Germanic from the Latin
'mutare', to change.

Michael Price A brave world, Sir,
Vancouver BC Canada full of religion, knavery, and change;
mprice at mindlink.net we shall shortly see better days.
Aphra Behn (1640-1689)