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Why do wagtails wag tails? (1 Viewer)

Interesting Alf, but then they'd have to be getting some pretty serious extra food to counter the energy expended bobbing all day. I happened to catch that Bill Oddie spring watch thing last week, and they showed some Pied Wag pulli that were bobbing in the nest!

And then there's wing-flicking (Dunnock), head-bobbing (Tits), tail-cocking (blackbird), tail-waving (collared dove).....
 
Recently I watched a juvenile Grey Wag on a pool and it was still and dozy until it heard it's parent coming with food then the wagging started off slowly and went manic when the parent was with it shoving food in it's mouth. As soon as the parent left it slowed it's wagging down to a still again and dozed off.

Might be instinctively related to feeding somehow.
 
Ive always thought that a dipper bobs up and down because it is looking into water and can obviously be fooled by the parallax phenomenon as light rays bend as they enter or leave the water surface; hence the dipper is essentiallyt getting more than one sighting of the under-water scene and works out a 'fix' from these.

But then does anyone else have an alternative theory?

Alan Hill
 
Could I suggest that the wagging is a response to the problem of communicating in an environment that is saturated with the 'white noise' of rushing water. Sound signals are of reduced effectiveness so visual signals could well be the solution to this. This would also neatly explain why dippers dip.
 
Jamspangle said:
Could I suggest that the wagging is a response to the problem of communicating in an environment that is saturated with the 'white noise' of rushing water. Sound signals are of reduced effectiveness so visual signals could well be the solution to this. This would also neatly explain why dippers dip.

Thought provoking reply (the best type!), Jamspangle, leaving me wondering what the tail wagging wagtail is communicating. Might it be territorial, a case of "this is my stretch of rushing water" (or carpark, or patch of sandy beach dug over by a flock of choughs, as happens here in the Isle of Man!)?
 
I also think the 'communication' theory quite interesting, but I wonder if it is in fact correct. Admittedly any bird trying to communicate above the sound of rushing water would have a problem but sea-birds have adapted to an environment with a lot of wind and water noise by developing powerful high-pitched calls; so why wouldn't birds who inhabit a river environment do the same?

Alan Hill
 
The fact is that it isn't known. According to the recommendable "Handbook of the Birds of the World" vol. 9 these are the main threories:

1) It render birds living by streams less conspicious.
2) It may be a signal to other individuals, i.e. to maintain unity in flocks or as an aggressive signal.
3) When a wagtail lands it usually wags its tail immediately, a movement that may result in any nearby predators having a go at it while it is allert instead of the predator attacking when it is less alert.
4) The movement may distub insects.
5) It may be an "intention movement", as when they are about to lunge into flight.

Personally, I doubt the Willie-wagtail study is of much use for comparison (it is also mentioned in HBW). Anyone who's seen a Willie-wagtail will know that its way of wagging the tail (indeed, the shape of the tail itself) seem far more adapted to disturbing insects (as it is in many other members of the same group; the Fantails). The way a Wagtail wags it tail doesn't seem very logical if it was an attempt on causing as much disturbance as possible to insects. While I do see the point in movements near streams if they result in it being less conspiciuos that just isn't my impression. I've never seen a wagtail near a stream and thought "ohh, that wagging motion certainly results in it being difficult to see". I could immagine that the movement may help in locating underwater prey that otherwise would be hard to see through the water surface (using "the best of both Worlds"; light and shadow), though. As for the signalling effect I think we all (most of us anyway!) can agree that this seem logical, at least as part of the explanation. Anyone who's spend more than a few hours watching wagtails will know that they are amazingly aggressive towards other wagtail, especially during breeding season. Indeed, it is known that the wagging is exaggerated during certain displays, incl. courtship and in territorial disputes. If the possibility mentioned above under #3 is true is an open question. The fact that they seem to wag their tail more or less continuously do make me doubt it somewhat, though (why should they invite a predator to attack them all the time???). Anyway, there's a bit more info on this subject on page 703 in the recommendable HBW vol. 9. Not much, though - and as said, nobody seem to know for sure why they do it...
 
Indian Forest wagtails

Jamspangle said:
Could I suggest that the wagging is a response to the problem of communicating in an environment that is saturated with the 'white noise' of rushing water. Sound signals are of reduced effectiveness so visual signals could well be the solution to this. This would also neatly explain why dippers dip.


When I was in the Western Ghats, all the forest wagtails ( usually on tracks ) wagged sideways, as opposed to the up and down movement of European wagtails.. Y?!?

Mike G

Or is it to with being close to the equator? like water and plug-holes? ( just a jokey )
 
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Allen S. Moore said:
I've often wondered while watching my neighbourhood pied wagtails and their occasionally urban grey cousins, why do wagtails wag their tails?
Allen

It is all very simple.

Because the sexes are so similar, they eed some way of telling male. ans female, apart, so they wag their tails.

Males wag them, up and down, and females wag them, down and up.

Easy. 3:)
 
Dubh Ghall said:
It is all very simple.

Because the sexes are so similar, they eed some way of telling male. ans female, apart, so they wag their tails.

Males wag them, up and down, and females wag them, down and up.

Easy. 3:)

Wow. I've been away from the Forum for a few days, and I've been missing these pearls of wisdom!
 
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