I have been saddened by the decrease in House Martins arriving this Spring in our part of Ingleton. Three years ago, we had a pair (but I put up some artificial nest boxes to encourage them, and they abandoned our house!)
However a house across the road had about three pairs every year, and our next door neighbours hosted one pair.
This year, I think there are just two pairs across the road, and next door was unvisited.
This morning, (23rd June) at long last, a pair has turned up next door and seems intent on nest-building!
If it is the usual pair (or their descendants?), it seems extraordinarily tardy – but I hope they have left themselves time to breed successfully.