Like (Piebald) rats up a drainpipe.

Pigeon o'clock, usual formula:-
 I open the back door and give a sort of, through the teeth, whistle ... 
"Pssss Wssst". At which point they quit the lawn & gather on the roof.
Today not a pidjin in sight. Went out, nil on roof, gave the whistle, rockall, went in. I was barely at the window there these were. I think they've caught on. There must have been pigeons in PsssWssst range, because not long after there were 5 Red Checkers & a couple of mealies on the lawn.
BTW & FYO - I have in no way touched the crows' colouring.