One may not pray near feces or other sources of biological waste and decay that give a foul odor (see the article for several opinions on when/how it applies). Does this include bird droppings?
I've never smelled a foul odor from them, but I imagine that if someone kept dozens of birds together in a house and didn't clean the house, that the build-up of droppings would smell, meaning that there is some foul smell. And it is biological waste.
Does this mean that it falls into the same category as cow manure for purposes of the Halachah?