It is a funny bird! It does the same head bobbing that most of the sandpipers do, but maybe not as much :) They are quite brave too and will allow me to get quite close, but I have to go slowly, bit by bit ;)

I captured one of these oystercatchers running full speed at a poor little widgeon that was waddling away and the poking the widgeon in the butt really hard with it's long pointy beak! I was amazed, as was the widgeon :)

Thanks @ratel!