NO. 5 BEHAVIOR OF THE NIGHT MONKEY — MOYNIHAN 65 



In all probability, the advantages of such behavior can be secured 

 only when the sex ratio is effectively one to one and the pair-bonds 

 between mates are close and long sustained. Species of Alouatta and 

 Ateles probably cannot afford such behavior because they usually live 

 in groups in which there are more females than males. There may 

 occasionally be more infants than adult males in such groups. The 

 looseness and brevity of pair-bonds among howlers must also tend 

 to prevent the establishment of continuous bonds between males and 

 infants. Infants must be fed by their mothers at more or less fre- 

 quent intervals, and regular transfers from one parent to the other 

 might be difficult to arrange when the parents do not stick together. 



Thus, the type of parental behavior shown by Night Monkeys in 

 captivity would seem to provide strong support for the hypothesis 

 that males and females of this species usually form pair-bonds which 

 are at least moderately long sustained under natural conditions (see 

 page 12). 



Like all baby monkeys, infant Night Monkeys have very strong 

 clutching tendencies and try to keep in close physical contact with a 

 parent at almost all times. The only exceptions occur when an infant 

 moves from one parent to another before and after feeding (see next 

 paragraph). When clutching a parent, an infant usually uses both 

 hands and feet to hold on to the parent's fur, and may also keep its 

 tail pressed against the parent's body. The infant born in captivity 

 that was observed most frequently was very inactive, aside from feed- 

 ing, during the first few days of its life. By the time it was 3 weeks 

 old, however, it sometimes moved around most energetically on its 

 parent's back. 



My observations would suggest that an infant usually shifts from 

 one parent to the other, at feeding time, under its own power. The 

 parents do not lend a hand to lift or support the infant during the 

 transfer unless it should start to fall. 



The infants raised in captivity apart from their parents quickly 

 learned to accept human beings as foster parents. They appeared to 

 be almost perfectly satisfied to be carried by a human being, espe- 

 cially if they could ride on the head and clutch hair. Somewhat 

 more slowly and reluctantly, they also learned to accept turkish towels 

 as parent substitutes. An infant conditioned in this way usually spent 

 all its time clutching its towel (unless it had to leave the towel to 

 feed or drink). 



Except when specifically stated otherwise, the behavior patterns of 

 infants and juveniles described hereafter in this section were per- 

 formed by young animals hand reared in captivity, after being sepa- 



