Dangling from the limestone cliff, Rowan Martin reaches into a hole in the sharp rock and retrieves a squawking bundle of green feathers. He slips it into a bag clipped around his waist and ascends his rope to a ledge, where research partner Sam Williams waits. Science happens at dawn in the tropics. Beyond the cliff is a preposterously beautiful view. A plain of tall datu cacti gives way to crashing waves glowing with the first light from the east. But Martin and Williams, doctoral students from the University of Sheffield in England, are focused on their task: a variation on a checkup at the pediatrician’s office. The bundle is quiet as it is weighed inside a cloth sack suspended from a gram scale. As Martin records the number, Williams gently removes the young bird. Peering at us with inquisitive gold eyes, the bird opens its sharp hooked beak. With surprising patience it allows Williams to run his thumb over the pale blue feathers on its forehead and blow aside neatly...