It's interesting to have seen birds nests on my uncle's farm growing up. The birds would choose a shed that had open doors or gaps to come and go so they'd have shelter from the wind and rain and the possibility of food nearby from food for cattle or worms and insects from the land. If humans weren't around the birds would have to settle for a tree or a different sheltered spot. The only bad side of having birds in a shed is they might scare the farm animals sometimes by coming and going and bird poop is annoying to get out of clothes.
I haven't been on the farm in years but my dad sent me the photo and it reminded me of the farm from my school holidays