NO. 5 BEHAVIOR OF THE NIGHT MONKEY — MOYNIHAN 57 



form it is quite distinct. It occurs when the groomer wants to groom 

 areas on the far side of the groomee. In its attempt to get at these 

 areas, the groomer may cHmb up on the back of the groomee. It 

 usually climbs up from the side, not from the rear as in the case of 

 a male mounting a female during a typical copulation attempt. A 

 grooming individual also tends to keep its head pressed down into 

 the fur of the groomee. (A male generally does not lower his head 

 as much during copulation). The only individuals observed to per- 

 form grooming mountings were males ; but this may have been largely 

 due to the fact that most of the females observed were slightly sub- 

 ordinate to their males and somewhat reluctant to handle them 

 roughly (there is no obvious reason why females should not be able 

 to perform such mountings in suitable circumstances). 



If the individual being groomed does not object to the process 

 (and rough or awkward Allogrooming may provoke disputes — see 

 below), it remains passive, sitting quietly. Only rarely does it shift 

 position voluntarily to present particular areas that it wants to have 

 groomed. 



Night Monkeys do not seem to have any special "soliciting" posture 

 to invite (initiate) either copulation or Allogrooming (unless sitting 

 quietly by the side of another individual can be considered such). 



Some Allogrooming performances are quite silent. Others are ac- 

 companied by Squeaks and/or a variety of wholly or partly hostile 

 notes (see below). Hostile notes are relatively very rare except during 

 the obviously "unsuccessful" performances which break up in open 

 disputes. 



Allogrooming may occur immediately before and/or after both 

 successful and unsuccessful copulation attempts. It may also occur 

 apart from overt copulation attempts, but only relatively rarely. Al- 

 most all the individuals observed to perform such grooming were 

 known to be in reproductive "mood," copulating with the individuals 

 they groomed on succeeding and/or preceding nights, even if not 

 always immediately before or after the actual grooming. 



These facts would suggest that the copulatory tendency may be at 

 least one of the causal factors producing Allogrooming in all cir- 

 cumstances. 



The detailed relations or interactions between Allogrooming and 

 overt copulatory movements are rather complex. In spite of their 

 frequent association, and their apparent similarity in motivation, the 

 two types of behavior seem to be mutually exclusive, to some extent, 

 on a short-term basis, Allogrooming appears to serve as a partial 

 "substitute" for copulation. It is very common to see a male groom 



