What's going on? We always have house martins nesting on our gable ends every year and we love them. This year they arrived as usual, built their muddy home and within days it fell down. We were really sad, they built it again and that fell down too.
Then we noticed they went to the other side of the house and started building there, so all was well we thought. Unfortunately their Site Manager failed to notice a large lead for the TV aeriel and they built it around this!

Every time a BIG bird (great fat pigeons or seagulls) sat on the aerial, this caused the lead inside to move and that nest went the same way.
So all summer we've missed the housemartins and lo & behold, yesterday (1st Sept) I heard a lot of noise and there were about half a dozen housemartins back where the first nest, which is now just a few blobs of mud.
I don't get it.

They should be leaving for Africa soon shouldn't they?