Flicker of recognition
Why do wagtails wag their tails?
This was a question asked of me by a friend some years ago but I was unable to answer with any real conviction.
In fact a wagtail doesn’t wag its tail from side to side like a dog so much as dips it up and down.
The reason for this almost continuous movement on the part of wagtails has puzzled not only me but also lots of much more eminent students of ornithology.
There are, as you might expect, several theories, which include the possibility that a tail-flicking wagtail is signalling to its fellow wagtails as a means of recognition.
Another theory speculates that the constant tail dipping is a ruse to provoke a potential predator into launching an attack, only for the quite fast-flying wagtail to make a heroic escape. I certainly hae ma doubts about this theory for I do not think that any bird, no matter how agile, would willingly and blatantly defy the likes of a sparrowhawk. Life is surely too precious and precarious for that and I can’t imagine even the comedyloving wagtail taking such a chance just for fun.
Others suggest that the constant tail flicking may act as a form of camouflage. When seen against a backdrop of fast-moving water, generally a wagtail’s favoured location, the constant tail movement is thought to confuse any wouldbe predator. Again I’m a little sceptical.
More plausible perhaps is the belief that the tail flicking is in fact a device that flushes out insects, which are then vigorously pursued by this extremely agile bird.
My own choice would probably be that it is simply a signal constantly given to tell other wagtails that the bird is where it is. It may be a territorial notification intended for other wagtails but, in truth, I can no more explain it than I can explain why a dipper bobs up and down on what appear to be spring-loaded legs.
Whatever the reason, the repetition of such a signal and the overall demeanour of the bird are surely enough to bring a smile to the observer’s lips.
Pied wagtails seem to convey to me a kind of clownish image: their white faces and prominent black eyes plus that black crown resembling a clown’s wig.
There are, of course, several variations on a theme. In Britain the pied wagtail is by far the most numerous of the three wagtails to be found here at various times of the year. Although we quite rightly associate wagtails with water, the pied variety is also a frequenter of towns and cities, most particularly during the winter.
When the weather is wintry towns offer some extra overnight warmth so pied wagtails may often be seen roosting communally in city centres. I remember being quite startled at the number of wagtails I once saw roosting in the trees in Perth’s main shopping area. Dusk was just falling as wave after wave of them arrived to join this massive communal roost.
The other two wagtails that inhabit the UK are the grey wagtail, a lovely wee bird grey backed but delightfully embellished with a delicate shade of lemon yellow on its rump, chest and under-parts - and the yellow wagtail. The latter is a migrant bird which winters in West Africa and is more universally yellow except for its greenish brown upperparts.
The yellow wagtail is a rarity hereabouts, this perhaps being near to the northern limit of its range. Such is the brightness of its plumage that in some parts of Britain it is known as the sunshine bird or the summer wagtail.
I once watched, utterly entranced, as a pied wagtail spent a good few minutes trying to catch a white butterfly high above my head. The butterfly also demonstrated how agile and aware it was, dodging this way and that to avoid the stabbing beak of the wagtail. In the end it won the day and the wagtail gave up the chase but this fascinating encounter produced an amazing aerial dance.
All these wagtails are essentially insect eaters and their preference for areas where there is water is explained by the fact that as it moves water conveys a constantly renewing supply of invertebrate life.
Some of our grey wagtails head to southern Europe for the winter – a very good idea this time round - and indeed we play host in the winter to some of those wagtails normally resident in northern Europe.
Just before the deluge of snow arrived I found myself watching a lone grey wagtail. But instead of busying itself beside some frothing burn it was in the middle of one of Central Scotland’s busy towns, trotting blithely along a house gutter.
There had been no recent rain so it would find no water there. Nor did this seem to be a likely source of juicy insect. I just hope that lovely, delicate bird managed to survive the subsequent storms.
Wagtails of all shades will have found recent days pretty difficult. There has been hardly any sign of insect life. Nor has there been any sign of the pied wagtail which, before the blizzards came, had been loitering here.
Indeed, many of our wild birds will have struggled to survive in conditions which I certainly cannot ever recall occurring in March.