NO, 5 BEHAVIOR OF THE NIGHT MONKEY — MOYNIHAN 21 



activities that appear to be "irrelevant" or "extraneous" or "out of 

 context." Individuals of this species seem to perform such activities 

 relatively much less frequently than individuals of many related 

 species. 



The absence or extreme rarity of autogrooming in hostile situations 

 has already been mentioned. 



There is only one pattern that may be partly equivalent to the "dis- 

 placement" scratching of many other platyrrhines. Some of the cap- 

 tive Night Monkeys on Barro Colorado Island sneezed repeatedly 

 during some high-intensity disputes. In other situations, sneezing 

 seems to be a cleaning or comfort movement of a peculiar type used 

 to clear or clean out the nose. Sneezing is very common after feeding, 

 presumably because animals tend to get food up their noses. As the 

 Night Monkeys that sneezed so frequently during disputes had not 

 been feeding immediately beforehand, it is at least conceivable that 

 some or all of their sneezing was a direct result or consequence, in 

 one way or another, of their hostility. 



(The whole problem of "displacement" activities by New World 

 primates will be discussed in a later paper.) 



Night Monkeys defecate and urinate in some hostile situations. A 

 captive but untamed individual may defecate and/or urinate when 

 caught and picked up by a human being. This is usually accompanied 

 by "Screams" (see below) and/or Gruff Grunts. Some or all of 

 these defecation and urination patterns are probably produced when 

 both attack and escape tendencies are strong, but escape is definitely 

 predominant over attack. 



I do not think that the defecation and urination patterns of Night 

 Monkeys subserve any signal function or help to repell predators at a 

 distance. Wild individuals of many other species of New World mon- 

 keys frequently urinate and/or defecate upon predators or potential 

 predators passing beneath them in the forest ; but none of the wild 

 Night Monkeys on Barro Colorado Island was observed to do so. 



Vomiting may also be closely associated with the hostile behavior 

 of Night Monkeys in certain circumstances. Some of the captive indi- 

 viduals on Barro Colorado Island vomited occasionally, or performed 

 the "heaving" motions that frequently precede vomiting, during or 

 immediately after hostile reactions (escape movements. Swaying, 

 and/or Gruff Grunts) to the approach of a human observer. 



Night Monkeys have fewer signal patterns designed to be perceived 

 by the eye than many other New World primates ; and most of the 

 signal patterns of this type that they do have are comparatively crude 

 or "gross," produced by simple movements of the whole body and/or 



