can you post a pic of the shed? that may help. If you have nice big aviaries with wide opening you may not need any windows. pigeons may fly into clear glass or plastic. but you could always put those stickers on it that they sell for windows so birds don't fly into it. are you looking to add more light into the shed/loft? Im guessing. you could take out the vents and use hardware cloth on the openings and not plastic.