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

Abstract

Sequential exchanges of vocalizations (staccatos and neighs) emitted by Northern MuriquisBrachyteles 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.

Intra‐community coalitionary lethal attack of an adult male southern muriqui (Brachyteles arachnoides)

“…Observation distance ranged from 10-30 m, using 10 Â 40 binoculars. Vocalizations described below follow prior descriptions for northern muriquis [Mendes & Ades, 2004]. All research reported in this manuscript is in agreement with the appropriate national and institutional guidelines and applicable laws.…”

“…Inter-communities encounters are rare. These encounters, which occasionally lasted for several days, were easily detected by frequent and repeated loud vocalizations associated with group cohesion [neighs, sensu Mendes & Ades, 2004] and by an atypically large party-size (44-70 individuals) and probably with individual belonging to the same community engaging in interactions such as play and embracing more frequently than usual. Although occasional and infrequent chasing and behavioral displays did occur among males, most likely between males belonging to different communities, physical contact has never been observed during these relaxed inter-community encounters.…”

“…1). Loud vocalizations of shouting, barking and repeated neighs [sensu Mendes & Ades, 2004] were heard. The next morning, on 04/01/08, the party consisted of 10 adult males, 12 adult females including three females with dependent offspring, several subadults, juveniles and infants.…”

Sex differences in vocal patterns in the northern muriqui (Brachyteles hypoxanthus)

“…Staccatos have been defined as short-distance contact calls, commonly produced during short-range exchanges [Mendes, 1995]. Mendes and Ades [2004] suggested that staccatos could function to reduce competition by allowing callers to maintain or increase distances among nearby listeners, but no previous studies have yet tested this hypothesis.…”

“…Contrary to staccatos, neighs have been classified as long-distance contact calls, mainly produced during long-range exchanges when group members are widely dispersed [Mendes & Ades, 2004;Strier, 1999]. Nishimura et al [1988] suggested that neighs are used by northern muriquis to maintain group unity and coordinate group movement because they are often heard when animals are traveling and feeding, but the effects of these calls on spatial patterns have not been subjected to quantitative analyses.…”