24
Back Bay Basin,
Boston, Mass.
1909.
Feb. 27
(No 24)
Whistler courtship
their mandibles and quivering their throats as if swallowing
rather violently. On closely approaching one another or one of the
females they often bobbed their heads up and down
two or three times in quick succession. This seemed
to be a form of polite salutation but it may have
had a different meaning. During most of the more 
pronounced movements of the head and not infrequently 
when it was held at rest, its feathers were alternately
raised or fluffed and depressed or flattened down, so
that at one instant it looked almost twice, and at
the next barely one half, its usual size. This,
was probably done to show the plumage of
the head to the best advantage. At least I so
concluded as I watched its greenish sheen flash and
glimmer in the sunlight and then disappear to blaze out
again with renewed lustre a moment later. The changes in the 
adjustment of the feathers of the head resulted also in striking
and very interesting variations in its apparent shape some
of which I have tried to represent by crude sketches.
The nod
Feathers of head fluffed & flattened
Iridescence of head shown
Pyramidal shaped head
Partly rounded head
Rounded head