Acoustic differences between spontaneous and induced long calls of golden lion tamarins, Leontopithecus rosalia.

Long calls are emitted by several primate taxa and appear to have multiple functions related to spacing mechanisms and reproduction. Yet, in some species the spontaneous rate of emission of these calls is low, and playbacks are used to elicit long calls to augment the sample size of studies. The objective of this study was to compare the acoustic structure of spontaneously emitted and experimentally induced long calls of golden lion tamarins. Results from 6 adult tamarins show that spontaneously emitted long calls differ acoustically from experimentally induced long calls in several frequency measures. Several explanations for these differences are discussed. We conclude that regardless of the underlying mechanisms, playbacks elicit responses that may be different from naturally occurring calls.