Vocal sequential exchanges and intragroup spacing in the Northern Muriqui Brachyteles arachnoides hypoxanthus.

Francisco D.C Mendes,César Ades

doi:10.1590/s0001-37652004000200032

Abstract

Sequential exchanges of vocalizations (staccatos and neighs) emitted by Northern Muriquis Brachyteles arachnoides hypoxanthus were recorded at the Biological Station of Caratinga, Minas Gerais State, Brazil. Staccatos and neighs containing larger proportion of short elements were preferentially produced during short-range exchanges; neighs, produced by a larger number of participants, were typical of long-range exchanges. Staccatos emitted by animals feeding in a dispersed manner contained a larger proportion of tonal elements than those emitted by muriquis feeding in a cohesive manner. Sequential exchanges seem thus to be constituted by two inter-related subsystems of calls that aid muriquis to coordinate intragroup spacing, despite the poor visibility of the habitat.

Highlights

The Northern Muriqui Brachyteles arachnoides hypoxanthus, hereafter called muriqui, is a neotropical monkey found exclusively in the Atlantic Forest region of Brazil (Hilton-Taylor and Rylands 2002)
Sequential exchanges were associated with both interactions between a few nearby individuals and interactions of larger numbers of individuals spread out over larger areas
Sequential exchanges seem to be constituted by two inter-related subsystems of calls that aid muriquis to coordinate activities, despite dispersion of group members and poor visibility in the habitat

Summary

Introduction

The Northern Muriqui Brachyteles arachnoides hypoxanthus, hereafter called muriqui, is a neotropical monkey found exclusively in the Atlantic Forest region of Brazil (Hilton-Taylor and Rylands 2002). Part of the species repertoire is a set of combinatory calls that are produced in a particular pattern of turn-taking, named sequential exchanges. Strier (1986, 1999) distinguished vocalizations occurring in sequences as ‘‘short’’ and ‘‘long’’ neighs, and Nishimura et al (1988) noted that neighs, whinnies and screams usually evoked responses from other individuals. One individual vocalizes, and Sequential exchanges are composed of a variety of acoustic forms that can be qualitatively discriminated from other vocalizations of the species’ repertoire. These labels account for part of the acoustic repertoire present in sequential exchanges. Less conspicuous calls composed of short pulsed sounds are fre-

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Conclusion