Martin
Bird watchers get in a **** over anything that disturbs the birds.
The waders there are in the thousands and get disturbed all the time
by hawks and falcons and as with a helo, would fly up, around a few times
and back down. Plenty of other places for waders to feed.
Birds get used to noise, planes, helos etc and after a while wouldn't
even bother moving.
And as for Grey heron's, all he is highlighting is the ground nesting
part, they are a very common bird.