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Re: aerodynamics vs display in bird tails (was Re: Who says dromaeosaurs can't fly?)



Earlier I wrote

>Since this seems to be a topic of hot dicussion on the list at the moment,
>I'll try to dig up some more details (unless someone already knows the
>reference - Stephan or Ron? - in which case you can save me the effort).
>
>I think that the interesting thing was that these guys were measuring very
>small differences in tail length, and had collected their data well enough
>to correlate these very subtle differences with measured differences in
>mating success or flight performance.  I think.  I don't remember that they
>physically manipulated the tails (as some earlier studies have done - e.g.
>Andersson's work in the '80s on widow birds) - if not, then that is what
>would have impressed me.


I found the transcript on the Quantum webpage -
http://www.abc.net.au/quantum/scripts99/9907/warbscpt.htm#further  The work
was done on Golden Warblers by Chris Johnson at JCU - looking at his page on
the JCU website the reference appears to be;

Balmford A, Lewis MJ, Brooke M de L, Thomas, ALR & Johnson CN
     (2000) Experimental analyses of sexual and natural selection on short
     tails in a polygynous warbler. Proceedings of the Royal Society of
     London B 267, 1121-1128

I don't know what the 'Golden Warbler' is - my copy of Simpson and Day
(Field Guide to Birds of Australia - fifth edition) doesn't list this
vernacular name, but there are various Greygones (Acanthizinae) and Old
World Warblers (Sylviidae) which have 'warbler' in the common name.

And as you can see from the transcript, my memory of the work was almost
completely wrong, but interesting nevertheless.  It turns out that, in this
species, it is the shorter tails that confer a sexual advantage that is
correlated with territorial defense (speed), but comes at a cost to
manoevurability (longer tails in this species permit more low speed
agility).

I don't have access to the reference, but if anyone does look at it I would
be interested to see which species they were looking at.

Cheers
Colin