Bird Ness Under Roof
Your typical bird nest poses little structural damage to a home
in a situation like this. The nest of course can be removed quite
easily. About the biggest problem you're going to have with birds is
their poop and the possibility of its staining the building exterior.
I put the picture of this birds nest in to show home inspectors possible hiding places for birds and other pests that could create problems in the future. Birds can get into even the smallest areas to build their nests. If you have problems with birds in your area simply go around the exterior of your home and seal up any holes you could imagine any bird going into.
Be advised some birds are protected and if you destroy their nests you could be fined.