NO. 5 BEHAVIOR OF THE NIGHT MONKEY — MOYNIHAN 4/ 



as the "Grunt Complex." The low-pitched Moans and Low Trills may 

 be related. It is possible that all the patterns of this complex have 

 been derived, in whole or in part, from a single pattern or a single 

 group of completely intergrading patterns (perhaps comparable to 

 the "basic agonistic sound" of the Rhesus Monkey described by 

 Rowell, 1962) in the course of evolution. 



The hostile vocalizations of adult Night Monkeys seem to be pro- 

 duced when motivational conflict is stronger, i.e., when incompatible 

 tendencies are more nearly equal in strength, than when many or 

 m.ost of the nonvocal hostile displays are produced. A similar ar- 

 rangement occurs in some species of birds (see, for instance, 

 Moynihan, 1962b). It may be characteristic of most higher ver- 

 tebrates. 



Some other aspects of the vocal behavior of Night Monkeys will 

 be discussed below, in connection with the Hoot and Squeak patterns, 



SOCIAL SNIFFING 



This is the most common of the "greeting" patterns. In captivity 

 (at least), it is almost always performed whenever any two pre- 

 viously unacquainted individuals meet one another for the first time, 

 and it also occurs in certain other social circumstances. 



It may be initiated by either one of the individuals involved, or by 

 both simultaneously. A sniffing animal simply approaches another, 

 stretches its neck forward a little, and smells the other, usually for 

 at least several seconds. When sniffing is initiated by one individual, 

 the individual being smelled remains motionless at first, but usually 

 responds by sniffing in return if the first individual continues long 

 enough. Sometimes two individuals will sniff one another alternately. 

 More often their sniffing overlaps in time, even when they do not 

 begin sim.ultaneously. 



Most sniffing — both mutual sniffing and sniffing by only one in- 

 dividual — begins "nose to nose." An individual usually starts by 

 bringing its face as close as possible to the face of its "partner" in 

 the performance. It also may sniff into the armpit or under the arm 

 and/or at the perineal region of its partner. This is relatively (if not 

 actually) rare as an initial reaction, but it is very common immediately 

 after nose-to-nose sniffing. Occasionally, two individuals will sniff at 

 one another's perineal regions simultaneously. This is done less fre- 

 quently by Night Monkeys than by some tamarins (for which it is 

 the usual form of social sniffing). 



It seems likely that this behavior is guided by, or orientated toward, 

 special scent glands. The skin glands of Night Monkeys have been 



