Rooks' nests

I pass these trees, in the garden of a large pub on a main road, every time I cycle to work.
The nests are inhabited each year by rooks and have been for at least the past 25 years (that's as long as I've lived here). I was so busy trying to crane my neck and focus on the central nest that I have no idea whether the nearby round blob is an old football or a fat pigeon!