dashing

grandiose

enrolment required

heat

judgement deferred

Jo,

This is a possible explanation, but I may be totally wrong.

The 'waving blanket' effect of a flock of wagtails in constant motion makes it difficult for predators - hawks, cats, etc - to fix on a single specimen.  Most predators, at some point just prior to the dive, leap, strike, will 'lock onto' their target.  Faced with a multiplicity of potential targets their mental targeting computer doesn't focus as well as it would with only a single target.

Humans do it too, which is one reason why a sniper has a 'spotter'.  As well as being a second pair of eyes he provides cover for those few vital moments when the sniper is totally locked into his own mental bubble.

Let's look at another example of this evolutionary 'confusion factor'.  When a bunch of grazing rabbits are disturbed by a hunting fox they all hop to the hedgerows or burrows, with the previously concealed little white scut on the underside of their tail bobbing up and down and side to side.  This alerts all the other rabbits to the danger, because nature nearly always puts survival of the species above individual survival . Suddenly Mister Fox is faced with sensory overload, and in that blurred moment the rabbits have a better chance or survival.

It's nature's equivalent to the dreaded and rarely invokesd naval command 'Convoy Will Scatter' when faced with marauding U-Boats.   Only of limited utility, but the hope - and the cold logic - was that the sub would waste its time and torpedoes on the 'logistically less worthwhile' targets amongst the fleeing ships.  Unlike the rabbits there were no handy burrows for the ships to take refuge, which is why this was an order of last resort..

Another example of this confusion factor in human terms would be the so-called 'dazzle camouflage' used on some ships. Random blocks and stripes.  Often quite garish.  This doesn't make the shop blend with the sea and sky, as one would expect camouflage to do.  It's supposed to break up the distinctive silhouette of the ship, rather like a badly pixelated image on your computer.  In the days of purely visual aiming and gun-laying this was, possibly, a helpful factor.

So maybe that's what your wagtails have evolved to do, to confuse predators.

If so it's fascinating, in that movement is what usually betrays hidden prey, and predators.   So much so that SAS men on long term surveillance in the Irish countryside would set up 'distractions', such as a bit of torn fertiliser sack trapped on a barbed wire fence.  This bit of common countryside litter served a useful purpose if a watcher spotted an unguarded movement in the SAS hide.  The convenient flickering bag a few  yards away would 'explain' the movement, and once spotted would keep catching the eye of whoever was stalking them  This tactic was used by both sides.

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But if any ornithologist or animal behaviourist has a better explanation I'll be more than happy to hear it.

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A human predator, working in the 'target rich' environment  of a night club for example, has already 'tuned out' the majority who don't match the 'desired target profile'.  If he - or she - is actively looking for a short redhead then the leggy blondes or medium height black-haired ones will register only as background, even if they are actively trying to attract attention.

Gyppo

mate