NO. 5 BEHAVIOR OF THE NIGHT MONKEY — MOYNIHAN 63 



She usually performs several leaps one right after the other, before resuming 

 slower approaches and Allogrooming . . , 



The male does not respond to the female's leaps as strongly as might be 

 expected. Usually he just sits quietly throughout. Occasionally (especially dur- 

 ing the first hour) he assumes an extreme Arch Posture just as the female 

 starts to leap. Once or twice he strikes at her, but he never chases her . . . 



8:45. The male starts to relax a little. Occasionally starts to follow the 

 female when she goes down to the floor of the cage to get food . . . 



9:45. The two animals are sitting side by side. Then the female goes down 

 to the floor, picks up a piece of fruit, climbs up to a branch, about three feet 

 from the male, and starts to eat. The male walks toward her slowly. Sniffs at 

 her perineal region. Then suddenly mounts her, from the rear. Slightly awk- 

 ward. The female does not lift her tail, so the male has to shift his body in 

 order to insert his penis from the side. Copulation. Apparently successful. 

 Several pelvic thrusts at irregular intervals. The female leans downward and 

 forward during the copulation, still clutching food in her hand. Then the male 

 dismounts. Sits beside female, facing in the same direction. Then turns around, 

 sniffs at her perineal region again, mounts her again, and copulates again. Again 

 apparently successful. Then he dismounts and sits beside the female as before. 

 She calmly finishes eating her food, turns around, and sniffs his perineal region. 

 Then both animals sit quietly . . . 



BEHAVIOR OF YOUNG ANIMALS 



Three baby Night Monkeys were born, to different parents, in 

 captivity on Barro Colorado Island. One of these vi^as left with its 

 parents, but died when approximately 2 months old. The second 

 was taken from its parents at the age of 1^ months, and raised by 

 hand. The third was born only 9 weeks before this paper was written, 

 and was left with its parents. Several other infants were bought in 

 the Panama market, and hand raised successfully in captivity. Many 

 of the other individuals kept in captivity on Barro Colorado Island 

 were secured when they were still subadult. A few subadult in- 

 dividuals were observed in the wild on Barro Colorado. 



The infants born in captivity on Barro Colorado Island were not 

 watched very much while they remained with their parents, as it was 

 feared that prolonged observation might disturb the parents unduly 

 and cause them to abandon or neglect the young. It was only possible to 

 note a few aspects of the parent-infant relationship. 



For the first few days after birth, the infant is always carried by 

 the mother, clinging to her breast or belly. Later it usually rides on 

 the back of a parent. 



Male Night Monkeys seem to play an important role in raising 

 their offspring. Before they were 3 weeks old, two of the infants 

 born in captivity on Barro Colorado Island were being carried by 



