Vocal sequential exchanges and intragroup spacing in the Northern Muriqui Brachyteles arachnoides hypoxanthus
Francisco D.C. MendesI; César AdesII
IDepartamento de Psicologia e Instituto do Trópico Subúmido, Universidade Católica de Goiás, Av. Universitária 1440, Cx. Postal 86, 74605-010 Goiânia, GO, Brasil
IIDepartamento de Psicologia Experimental, Universidade de São Paulo, Av. Prof. Mello Moraes 1721, 05508-010 São Paulo, SP, Brasil
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.
Key words: animal communication, signal exchange, vocal sequences, intragroup spacing, Muriqui.