On Tue, Dec 09, 2008 at 11:58:15AM +1100, Evan Beaver wrote:
> I haven't read the paper yet, I'll have a look later. However, I'd
> wondered the same thing about rabbits and deer, that both have white
> under their tails. In rabbits, I think it's to break up the outline
> while they're running away. From behind you see a moving grey/white
> spot that, surprisingly, disappears into the greenery.
I read some more of the paper and I've mis-characterised it. While the
authors think the white under-tails on swamphens and other rails have
evolved in response to predation, they believe its more likely they've
evolved primarily as a signal to predators rather than other swamphens.
Its been suggested that the white tails on rabbit and deer also evolved
as signals to predators - indicating the individual is fit, fast and/or
alert to the predator and pursuit would likely be unsuccessful and
hence a waste of energy - e.g. a study of eagle-owls found they were
more likely to choose rabbits with duller tails. It also suggested
singing might be used in a similar way - there are observations that
Merlins are less likely to pursue Skylarks if they start singing -
suggesting its a signal to the Merlin of the Skylark's fitness.
But its hard to make a conclusive case for this type of signalling
and the analysis of rail tails looks far from definitive to me.
Andrew
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