Hi all,
Have just been reading an article (significance of wing shape) in a back
issue of Jim Davis' Interpretive Birding Bulletin (Nov/Dec 97 issue). At
one point, he discusses compromises.... "When discussing wing shape it is
easy to give the impression that each species has the optimum shape to
match its particular life-style. Although the match between function of
form is important, life is full of compromises. Consider the example of
flycatchers and foliage gleaning birds that migrate long distances each
year once breeding is finished. For most of the year, power take-offs and
flight among the trees favour the evolution of short, rounded wings, yet
they can't trade in their wings for a pair that has been optimised for long
distance tavel."....
This last sentence made me stop and think...
Many migratory birds, notably waders, change their plumage so that they are
more cryptically camouflaged in their different summer and winter habitats.
This change is no doubt triggered by hormonal changes, although I have no
idea of the level at which these hormonal changes are working. Is the
change in plumage also associated with moult, such that it is new
replacement feathers that have the new colour scheme, or do the old
feathers change in colour?
But my point is, if you can "trade in" one colour scheme for another, might
it not be possible to do the same, at least to some extent, with wing
shape. Admittedly the migration period is relatively short and the bird
wouldn't necessarily want to be encumbered with the wrong shaped wing after
the long flight, but is there any evidence at all for any change in wing
shape in migratory birds.
Any thoughts?
Cheers,
Harvey
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Dr Harvey D. Perkins
Divn Biochemistry & Molecular Biology
Faculty of Science
Australian National University
Canberra, ACT, 0200, Australia
ph:(02) 6249 2663; fax:(02) 6249 0313
email:
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