I was in Peckham Rye Park on Monday and saw a wagtail strutting about by the small stream that runs past.
I was in Peckham Rye Park on Monday and saw a wagtail strutting about by the small stream that runs past. They're not rare birds, but I watched it for some time thinking I had not seen one in ages. Although maybe not really a suburban garden bird, it was quite at home in the ornamental grandness of the recently renovated Rye.
It got me wondering why wagtails wag. A lot of energy is expended twitching about like that so there must be some good purpose in it all. Luckily, the internet birder forums have got there first and there's been a lively discussion on line, in which I'm pleased to note that no solid consensus has been reached.
My first thought was that it might be analogous to the head bobbing used by some larger birds as they strut forwards. This is the equivalent of a human pumping their arms backwards and forwards as they run - conservation of angular momentum, to give it the full scientific title. Sure enough this idea has been mentioned, but so have lots of others.
It has been suggested that tail bobbing might flush out insect prey (they bob more in poor light), be a recognition signal to other wagtails nearby or to disguise them against the rippling and splashing background of the moving water that they regularly frequent.
Who knows? My favourite though, is that they wag their tails because they are happy.
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