I wouldn't think that spreading tail feathers it has anything to do with
feeding. I would expect it to be related to social signalling. No real evidence
but I can't imagine how spreading the tail feathers is of any benefit to
feeding at all (in whipbirds or fantails or anything else). If this is supposed
to work by influencing the behaviour of insects, then how would this behaviour
be explained in terms of adaptive benefit for the insects? Even stranger I
think is the idea that shading somehow results in better hunting of insects.
Sure some insects would prefer to be in direct light and others in shadow but I
doubt that any react to quick movements of shadows. Surely there is more shade
and light contrast available from trees and leaves in woodland than from birds'
tails. Mush easier for birds to use this, than chasing their Arses (pun
intended in regard to 2 north Qld species). Whipbirds and Rufous Fantails and
to a lesser extent Grey Fantails are forest birds and would rarely have the
opportunity to see a shadow.
Philip
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