The house martins in our area didn't turn up until the 1st June, our particular one on the back of our house seemed to settle very quickly, their little nest was updated and a lot of sitting started. But it wasn't long before one of the others was intent of hooking them out. So after alot of bickering the eggs fell out and smashed on the ground.
Anyway they tried again and this time I can actually see the babies perring over the edge of the nest. What are there chances of survival, they will be leaving again soon, and they haven't even learnt to fly yet.