Chuck vocalizations of wild female squirrel monkeys (Saimiri sciureus) contain information on caller identity and foraging activity
International Journal of Primatology
1997
Journal Article
18
6
975-993
Parque Nacional del Manu primate vocal communication Saimiri sciureus acoustic structure foraging behavior individual identity Golden lion tamarins vocal communication communication acoustic structure recognition communication individuality variability repertoire sequences animals mammals primates monkeys squirrel monkeys animal behavior Cocha Cashu Madre de Dios Bibliography
Analysis of the acoustic signal of the chuck vocalizations of adult female squirrel monkeys (Saimiri sciureus) in Parque Nacional de Manu, Peru, revealed consistent differences within and between individuals. We quantified four peak frequency parameters: (a) the peak frequency of single chucks, (b) the first and (c) the second peak frequencies of double chuck, and (d) the peak difference: the difference between the first and the second double chuck peaks. One-way ANOVAs and a posteriori comparisons of these variables revealed that each distinguished more than 70% of all possible pairs of females. When all double chuck measures were included in a discriminant analysis, 57% of double chuck were correctly assigned to the caller. Another category of information potentially encoded in the acoustic structure of chuck vocalizations is foraging activity. When the chuck of squirrel monkeys during foraging and nonforaging activities were compared, the single chuck peak frequency, and the first peak frequency and the peak difference of double chucks, were significantly reduced during foraging contexts. Previously Boinski and Mitchell (1992) concluded that chuck facilitate group cohesion among widely dispersed troop members by providing information of the location of callers; the rate of chuck produced by an adult female increases as she becomes more spatially and visually separated from other adult females. The additional information potentially conveyed by chucks on caller identity and foraging activity documented in these new analyses further emphasizes the role chuck serve to enhance group coordination and cohesion.