I have witnessed this behaviour on Dinham Flats when some waders including Redshank were drawn towards a Grey Squirrel, on the saltmarsh. Maybe waders like ducks try to keep would be predators in sight.
I'm pretty sure this wader behaviour is nothing to do with mobbing, they are not harassing, and are fully alert to the presence of a predator in the open, and still they seem drawn, in an inquisitive way towards the predator who appears to be controlling the prey. A vaguely similar thing happens when a Fox or a Stoat encounters a group of Rabbits they will sometimes all freeze on the spot and are taken easily by the predator.
2 Common Swift still last evening over Wadebridge with House Martin.


