National Geographic

them outside the temple in soft, white cottonbags to weigh and measure them. Four weremale, and two female, one pregnant. To learnmore about the bats’ relationships, the research-ers punched out a tiny skin sample from onewing of each bat to send to a laboratory forgenetic analysis. Small GPS tracking deviceswere attached to the backs of three of the bats(including the pregnant female) to provide infor-mation about their hunting habits.“Look,” Medellín said, pulling a male from abag and turning him on his back. “The maleshave tiny testicles—that correlates with monog-amy.” In the animal world, monogamy is rare. “Itcould be that two of these males are the females’mates, and the other two are their ofspring fromlast year and are in the process of becoming inde-pendent,” he explained. One female was nursing afour-month-old pup, and the pregnant one’s swol-len belly indicated that she would give birth soon.On the floor of the bats’ room was the partiallyeaten carcass of a spiny pocket mouse. “Look atthat—a fresh meal, and probably the last preyof the night,” Medellín said. “We think they eatsome prey outside, and after they’re full, theybring the last one back.” The catch often goesto bats that may not be able to hunt, such asnursing mothers. “We want to know what timethey leave their roost, where they go, who feedswhom, and who they travel with,” he said.Clues to the bats’ diets were gleaned from din-ner leftovers and feces in the temple. “Look,”Medellín exclaimed again, holding up the tiny,decaying carcass of the juvenile mouse. “I’m sur-prised they didn’t eat it all, because usually theyeat every bit—even the bones, toenails, and tail,sometimes.” They’d also eaten a yellow butterfly,forgoing the wings; a cicada; and a bird, possiblya woodcreeper, judging from a cluster of russetfeathers. “Usually we find the wings of otherbats.” They eat a lot of one uncommon speciesthat is diicult to find. Medellín is now studyingwhy this species is highly favored and how thewoolly false vampires find them.According to Medellín, woolly and spectralbats “are likely the bats described in the Maya``````A spectral bat, or Linnaeus’s false vampire bat,bites down on a researcher’s glove. These batsweigh about six ounces and have gossamer wingsthat extend up to three feet. Sharp, hooked clawson the thumbs are used to snag prey.``````MEAT-EATING BATS 79