National Geographic : 1981 Jul
never learned. Apparently the natural river boundary eliminated the need for a fight. Seldom did an hour pass without some form of territorial conflict between the edgy males of the meadow. Usually a simple chase sufficed to resolve their disputes. Male Orphan Joins Family On these summer days we had nearly 20 hours of light. But the guanacos kept a reasonable schedule that began about nine and permitted us to head for our tin house by seven in the evening. While the truck was still a mile away, Ona would see our dust; Pupsy would pick up the cue, and soon both animals would be dancing around the truck. When we got out, Ona would nuzzle against me and bleat softly. By then the girls would have appeared, glad to break away from the schoolbooks we had brought. "We've got a little surprise for you," Mer ry announced one day when we pulled in. "Yahgan!" she called in a motherly tone. Out from the camper came the girls, guid ing a newborn male chulengo. "The sheep riders found him all alone and brought him in. Can we keep him?" Merry asked. She al ready knew the answer. Perhaps because we doted on him less, Yahgan proved to be much more independent than Ona. Caught in the middle of a rite that will expel it from the family group, ayearling (left, at center) crouches in submissionas an adult male, right, andfemale square off in the head-up, ears back, arched-tailstance of aggression.Trying to protect heryoung, the female charges the male, who counters by spitting (below, left), another form of aggression. The two then slam chests (below, right). With the female routed, the male will charge the youngster, ultimately driving it off to make room for his new generationof offspring. Expelled male yearlingsjoin a bachelor herd.Females seek admission to anotherfamily group and begin breedingat about two years of age. Gestationlasts 11 to 11/2 months. Within a day of its birth an infant, or chulengo, is already a swift runner. Femalesmate again almost immediately after giving birth; thus two successive generationsmay end up nursing together until the elder is expelled.