To the patient go the rewards...if any of 'em are roosting on private property, once they do leave the landowners would be wise to shovel up any guano they find and either compost it for their own gardening or sell it to others for the same purpose. Until Europeans started exploring small, far-flung islands in earnest, many of those islands had a coating of bird-based guano old enough to have composted into soil. Some birds once burrowed in that soil to keep their eggs and chicks safe from weather and predators. Bat guano, especially for those enterprising and iron-stomached enough to figure out a way to filter out wild fruit seeds, is just as good a fertilizer. For those willing to be patient until either the flying foxes move on of their own accord or get rousted, a disgusting bounty awaits!
Side note: not always, but most years around October we get a "stopover" bat under my front porch. It's no flying fox; it's a Myotis species, probably the little brown myotis, with a body no longer than my thumb (2 and 5/16ths inches or 6 cm measured from the base along the side closest to the index finger) and barely any thicker. Wingspan probably 5-6 inches. I guard such bats quite openly, and the management and maintenance staff at the apartments I live in all know to come to me if anyone complains about a bat near their place. I've seen so many nature documentaries about bats and about wildlife rescue that I am actually competent at retrieving small wildlife. The local wildlife rehabber has actually complimented me for remembering to wear gloves on the rare occasions I feel compelled to touch a wild animal of any size.
