The Field Projects team collects two kinds of data:
• Behavioral data are collected in individual animal focals, so that we can analyze which calls are most closely associated with different behaviors.
• Vocalizations are recorded using a hyperdirectional microphone and a high-fidelity recorder. Human hearing does not extend over 20 kHz, but we record in the ultrasound (>20 kHz) to account for any primate vocalizations that we may not be able to hear.
Primates use vocal communication in a variety of ways, such as to signal danger, to alert to family members that a good food source has been found, and for infants to communicate with their mothers.
Tamarins are unusual in the primate world. They are cooperative breeders, meaning that each group consists of a primary breeding female, her offspring, and her harem of males who help raise them. Unlike primates who live in big groups, tamarins who have just reached sexual maturity don’t have regular contact with unrelated adults who are potential mates. While groups can accommodate more than one male, females who are sexually mature have fewer options for immigration. Moreover, emigrating from a family group is dangerous. Home ranges are about 1.5-2 km2, and leaving well-known home range to find a mate can expose a small monkey to all manner of dangers.
For tamarins, long calls may be the only way in which they are able to communicate to individuals in other groups. By investigating the use of and information contained within long calls in tamarins, we hope to understand the role of long-range vocalizations in sexual signaling. To see if tamarins are using these long-distance vocalizations to find mates, we are looking for markers of age, sex, individual identity, and sexual maturity in long calls.
Vocalizations are one of the most flexible forms of communication. Unlike visual signals, for example hair color, or chemical signals, such as scentmarking, auditory signals can quickly be modified by their producers, transmit and accommodate new and changing information, and can travel over large distances. For many animals, vocalizations are also used as as a form of sexual signaling, or as a way for potential mates to communicate with one another.
Calls are analyzed for bioacoustic markers on each call, including high frequency, low frequency, start frequency, and end frequency [spectrogram slide]. We look for call parameters that signify age, sex, and reproductive status.
Each species has its own unique set of vocalizations that are associated with behaviors, such as alarm calls, feeding calls and resting calls
The dataset is enriched by the fact that we have individual identifications for each call produced, and five years’ worth of morphometric data and social history. Future projects include looking at interindividual differences in all call types, whether certain aspects of calls are learned, and if there is a genetic component to individuality in vocalizations.