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Wagtail
tail-wagging |
30.12.2000
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Michael Woods |
The question of why wagtails wag their
tails was once again prompted by the arrival of a pied
wagtail on my roof, where it proceeded to hunt flies basking
in the autumn sun. This question has been posed in Nature
Notes several times over the years. Several theories have
been put forward by ornithologists but none seemed to fit
the bill. I once had the idea that a wagtail wags its tail
to help balance when chasing flies, rather as we wave our
arms to stop falling over. This was given the lie when I
watched a pied wagtail feeding on crumbs under a bird table.
It remained more or less in one spot for fully five minutes
and wagged its tail continually, and for one minute
literally continuously.
I am now wondering whether the
wagtails' habits have parallels with the behaviour of the
Australian willie wagtail. This species is not related to
our wagtails but belongs to the fantail family. When feeding
on insects, the willie wagtail wags its tail and also
flashes its wings. Two ornithologists have studied willie
wagtails by keeping them under observation and also carrying
out experiments with model tails. Their conclusion is that
tail-wagging disturbs flies, so flushing them and making
them easier to spot and catch. Short of repeating the
observations and experiments with our wagtails, I would look
for proof of this theory by finding wagtails that are not
feeding and, hopefully, observing that they are not wagging
their tails.
P.S. 2002. I was disappointed not to get any
reactions to this idea when it appeared in the Telegraph.
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