34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I46 



men during the initial reactions between strangers, previously un- 

 acquainted individuals meeting one another for the first time. In 

 such circumstances, they could be uttered by any one or all of the 

 individuals involved. \\'hen the previously unacquainted individuals 

 were of opposite sex, females tended to utter Low Trills more fre- 

 quently than males. Almost all individuals meeting a stranger tend 

 to be very cautious at first, moving in a hesitant and apparently 

 slightly alarmed manner. Females usually are even more hesitant 

 than males. The Low Trills during initial "greetings" often were 



960 



240 



— T 

 4.0 



Fig. 9. — One Sneeze-grunt, followed immediately by one Low Trill, uttered 

 by an adult. 



Based upon a spectrogram by a "Missilyser." 



uttered in close association with, immediately before, or during "social 

 sniffing" performances (see page 47). Similar notes were uttered 

 frequently by single individuals immediately after being released in 

 new cages, as they began to explore their quarters in a cautious man- 

 ner. Some individuals also uttered such notes when they went down 

 to get food from dishes on the ground, even when they were in familiar 

 quarters and/or there were no other Night ]\Ionkeys nearby. Captive 

 Night Monkeys tend to be slightly "nerv^ous" whenever they have to 

 come down to the ground, presumably because they would never do 

 so under natural conditions. Although many Low Trills during "greet- 

 ings" were eventually followed by oA'ert, unritualized, hostile, and/or 

 sexual beha\aor (depending upon the age, sex, and condition of the 

 individuals involved), they were not usually uttered during or after 



