we had loads on our roof this afternoon. where do they go?
As far as I understand it, they fly down through England to the south coast, stopping on the way to sleep, cross the channel, down France and Spain then cross at Gibralter to N Africa. They then make their way right down through Africa, again stopping to roost, until they get to S Africa. I don't think they all get that far. Then they congregate in great flocks in reed beds etc, quite unlike how they live here when they're breeding. They go down there for our winter as we run out of insects here but there's a huge insect-fest in Africa for their summer so they get fat then fly back here to breed again.
Our last little nestful of three chicks have still not fledged

I think there are so few insects left, and maybe only one parent, that they are not getting enough to eat to reach fledging size. They are hanging out of the nest now so fingers crossed for them