National Geographic

origin myth, Popol Vuh.” In that tale the Mayahero twins are placed inside a “bat house”—acave filled with death bats, called Camazotzby the Maya. The bats had snouts like blades,which they used to kill people and animals. Toescape, the twins crawled inside their blowguns,and all night long the bats terrorized them.Toward dawn, one of the twins said he wouldcheck to see if it was safe to leave. He raised hishead out of his gun—and promptly had it cutof by a Camazotz.“These bats do the same thing,” Medellínsaid. “They stalk their prey, land on them withhalf-spread wings, locking them with the thumbclaws, and deliver a death bite to the back or topof the head. Camazotz was not an invention.”LIKE WOLVES, LIONS, most bird species, and somecetaceans, insects, and primates—includingus—woolly and spectral bats share food, butonly with their roost mates. Scientists considerfood sharing to be a sign of altruism, althoughthe behavior is most often found among animalsthat are closely related to one another—and thenit’s more indicative of a close genetic relation-ship than a kind heart. Giving food to individualsoutside of one’s genetic relatives, as humansoften do, is seldom seen in other species. That’sanother reason Medellín and his students wantto clarify the genetic relationships among thewoolly bats. They know the bats are bringingprey back to their temple roost (“It’s the softside of their nature,” Medellín said), but they’renot yet sure which ones are sharing and whichreceiving. They expect to get answers from videorecorders deployed in the roost by Ivar Vleut,Medellín’s postdoctoral researcher, to capturefootage of feedings.Vleut played some food-sharing clips for me onhis laptop. “You can see the mother with her puphanging here, and now another bat has arrivedwith a mouse,” he said. The bat, most likely oneof the males, flies in and roosts close to her, grab-bing an overhead beam with his feet. Hangingupside down, she shakes her furry forearms athim much as a baby bird does when begging fromits parents. She bites the prey and removes itfrom the hunter; the mouse is already missing itshead, which the male probably ate. Grasping themouse’s body by its neck and chewing vigorously,she devours everything but the tail, which dropsto the floor. The hunter bat hangs quietly besideher, grooming his wings by licking them. “That’sthe usual behavior,” Vleut said. “They often seemto be full, satiated, when they return, which iswhy we think they’ve been hunting for a whileand then bring back their last catch to share.”The scientists have yet to see the bats huntingin the wild, but they have a good idea of theirtechnique because Medellín kept two woollyfalse vampire males captive for two weeks inAnand Varma and Rodrigo Medellín team up to capturenever before seen images in Giant Carnivorous Bats, airingJune 22 at 8 p.m. on Nat Geo WILD.Woolly false vampire bat(Chrotopterus auritus)``````Spectral bat(Vampyrum spectrum)``````Range of New Worldfalse vampire bats``````0 mi 6000 km 600``````PACIFIC``````OCEAN``````ATLANTIC``````OCEAN``````PARAG.``````MEXICOBELIZE``````NICARAGUA``````HONDURASGUATEMALAEL SALVADOR``````BOLIVIAPARAG.``````COSTA RICAPANAMA``````GUYANA``````VENEZUELA``````COLOMBIA``````SURINAME``````ECUADOR``````PERU``````CHILE``````ARGENTINA``````FRENCHGUIANA(FRANCE)``````TRINIDADANDTOBAGO``````EQUATOR``````BRAZIL``````YUCATÁNPENINSULA``````SOUTH``````A MERICA``````HormigueroNGM MAPS. SOURCES: IUCN; RODRIGO A. MEDELLÍN AND OTHERS, IDENTIFICACIÓN DE LOS MURCIÉLAGOSDE MÉXICO: CLAVE DE CAMPO, SECOND EDITION; A.L. GARDNER, MAMMALS OF SOUTH AMERICA