Last year, a pair of lesser black-backed gulls hatched three chicks
( https://www.blipfoto.com/entry/2718610086380438476 ) and fledged two ( https://www.blipfoto.com/entry/2730202462932699843 ) on the rooftops opposite me.
This year, they nested in the same place but the roof has been cleaned so no more vegetation. Also, the former corrugated asbestos roof to the left, with a rough surface and mossy patches, has been replaced with smooth shiny (imitation?) slates. The result has been that on hatching, all three chicks have slid down and fallen 2 storeys to the ground and are now being cared for in the middle of a building site. I don't rate their survival chances too highly even though they are a protected species.
(The local cats won't understand that)
My 'extra' shows their nest site (red arrow) and their current location (red circle).