Entry #7: The Woolly Monkey – A Symphony of Sounds

Written by: R. Reeder

One of our tasks this field season was to try and define the vocalizations from the diverse vocal repertoire of woolly monkeys. After six months of data collection we have been able to name and define thirteen distinct vocalizations. The majority of these vocalizations are some sort of variation of two main types: a chirp and a trill. A chirp is a single, short vocalization, whereas a trill is a longer vocalization that has more vibrato. These two main calls can vary in length, strength (loud, quiet, or regular), or number of times per unit time. Each variation has a different meaning. Stevenson (1997) notes that the vocalizations of woolly monkeys at Tinigua National Park in Colombia can be grouped in to three general types: contact, alarm, and social interactions. The chirps and trills that I described earlier are contact calls. A woolly usually produces them when they are trying to say, “I’m over here” or “where are you?” The shorter length of a chirp restricts this vocalization to closer distances, whereas a trill is more often used when, for example, the group is spread apart over several hundred meters and they are trying to coordinate their movements. Continue reading