Re: Back-evolution of limbs.

[Ronald Orenstein <ornstn@inforamp.net>]

>That said, you do raise an interesting question. Do any living birds use
>their wings for anything other than flight (or swimming)?
>- Jeff Hecht

A few examples have already been given (eg display in ostriches, use of wings
to shade eggs or young), but here are some more:

Display:  Many birds use their wings in display  (aside from the potential,
but
not clearly-understood, role of markings like wing-bars in species
recognition,
etc for many songbirds).  Active use of the wings can range from the
concealment or exposure of coloured areas (the North American Red-winged
Blackbird can hide or expose the red wing-shoulders; birds whose
wing-shoulders
are artificially dyed black get kicked off their territories by rivals in
short
order, so the exposure of the red patches clearly plays an important role in
male-male aggression and territory maintenance) to startling displays in which
the whole wing is opened to reveal a concealed "flash-pattern" (eg the
tropical
American Sunbittern and the Kagu of New Caledonia).  Nestling owls will spread
their wings and fluff their feathers as part of an anti-predator response,
making them look as large as possible.  There are many other examples (watch a
European Starling singing sometime!).

Sound production:  Some birds make distinctive sounds with their wings when
they fly (eg hummingbirds, hornbills).  In some, these sounds appear to have a
clear display function, as there are specially-modified feathers in the wing
that apparently act as sound-producers (examples: woodcocks and snipe; the
Cloven-feathered Dove of New Caledonia; the Club-winged Manakin of South
America; the Clapper Lark of Africa).

Foraging: Many small songbirds (eg kinglets) flick their wings repeatedly
while
foraging for insects in foliage; this has been interpreted as flushing
behaviour.  Some Herons open their wings when foraging, apparently shading the
water surface so prey can be seen more easily.  The Black Heron of Africa
actually wraps its wings around itself to form a canopy or umbrella; this may
not only improve its vision but may actually attract small fishes seeking
shade.

Combat: a number of birds (eg screamers, jacanas) have clubs or spines on
their
wings used in interspecific combats.  A male swan has a thickened lump of bone
on its wing that can deliver a powerful blow (enough, I have been told, to
break your leg).

Locomotion other than flying, swimming or gliding:  Let's not forget the
nestling hoatzin, which can clamber about quite nicely with its wing-claws
(the
only case of true quadrupedal locomotion known in birds).

Thermoregulation:  Vultures and other birds spread their wings while sunning.

Carrying young:  Jacanas can carry their chicks tucked under their wings (as
the chicks have long legs, this can make the parent look like it has a few
extra limbs!)

There are probably more uses I haven't thought of, but that's the best I
can do
off the top of my head! 
--
Ronald I. Orenstein                           Phone: (905) 820-7886
International Wildlife Coalition              Fax/Modem: (905) 569-0116
1825 Shady Creek Court                 
Mississauga, Ontario, Canada L5L 3W2          mailto:ornstn@inforamp.net