Indian flying foxes—one of the largest bat species in the world—flit from one breadfruit tree to the next, their wings silent above the rhythm of the surf. Here on the island of Dhigurah, a narrow slice of sand and coral in the Maldives’ Alifu Dhaalu Atoll, about two hours by public speedboat from the capital of Malé, the ocean is always nearby. At its widest point, Dhigurah is only 300 meters across, though most of it is much narrower. Its slender shape—Dhigurah means “long island” in Dhivehi—is most dramatic at…