I don’t think Esmeralda minds.“ Esmeralda is one of many Aldabra tortoises living on Bird Island, a coral cay surrounded by white-sand beaches and can’t-quite-believe-it turquoise sea.

This story appears in the June 2019 issue of National Geographic magazine. The first time a tortoise walked through my hut at Middle Camp on Aldabra Atoll, I was amazed. I grabbed my camera and ...