In an earlier post, I said that pigeons had roosted on my fire escape ledge and laid two eggs. They hatched them, and the young, which seemed to have a lot of yellow down, have now flown. I have now made sure that they cannot roost there again - I have to say that the squabs (babies) were not pretty, and the noise, the flies, and the mess the parents and visitors to the 'nursery' made was unbelievable. Try that outside your bedroom window!
We probably don't see the young very often (thank goodness) because feral pigeons tend to roost on high ledges.
I didn't know pigeons carried stones - their nests are a bit of a joke - just sticks and twigs (?cowboy pigeons) but I reckon these parents had read 'The three little pigs'.
Incidentally, my sister has two collared doves in a tree outside her house. They are very shy, coo and coo (not like their urban friends), look really beautiful, and she is now thinking of getting a dovecote to encourage them to nest there.