Pigeons and Seagulls

I see a lot of seagulls and pigeons from my studio window, which overlooks a flat roof.  Although it's in the middle of Bristol, it's a secluded space and both species of birds hang around there, and even make nests.  I have spent some time eyeballing, and being eyeballed by herring gulls.  Pigeons however tend to demure, being more easily intimidated.