Inter-group Encounters and Male Incursions In Colobus Vellerosus in Central Ghana

Abstract

[Inter-group encounters can 1 — reflect between-group contest competition for access to limiting, defensible resources, 2 — allow individuals to gather information on the surrounding groups to assess mating or dispersal opportunities or to assess resistance to a possible transfer or takeover, 3 — allow individuals to convey information to the other group about one's quality/status. We present data on inter-group encounters and male incursions (where one or several males encounter a reproductive unit) in Colobus vellerosus at the Boabeng Fiema Monkey Sanctuary in Ghana to assess whether they are compatible with these three functions, and in the case of the limiting resource defense hypothesis, to assess the resource competed for. Our study group was observed for 343 hours over 61 days between June and November 2001, and interacted with three neighboring groups in 47 encounters. Inter-group encounters were more frequent than male incursions (34 vs 13) and lasted longer (median: 45 vs 9 minutes). Most encounters included aggression towards individuals in the opposing group (39/47). Males were aggressors as well as targets of male aggression in a majority of encounters. Females were targets of male aggression in over half of encounters, while being aggressive in only a few of them. We describe three cases of male aggression towards immatures during male incursions, and one case of female transfer following one of these male, Inter-group encounters can 1 — reflect between-group contest competition for access to limiting, defensible resources, 2 — allow individuals to gather information on the surrounding groups to assess mating or dispersal opportunities or to assess resistance to a possible transfer or takeover, 3 — allow individuals to convey information to the other group about one's quality/status. We present data on inter-group encounters and male incursions (where one or several males encounter a reproductive unit) in Colobus vellerosus at the Boabeng Fiema Monkey Sanctuary in Ghana to assess whether they are compatible with these three functions, and in the case of the limiting resource defense hypothesis, to assess the resource competed for. Our study group was observed for 343 hours over 61 days between June and November 2001, and interacted with three neighboring groups in 47 encounters. Inter-group encounters were more frequent than male incursions (34 vs 13) and lasted longer (median: 45 vs 9 minutes). Most encounters included aggression towards individuals in the opposing group (39/47). Males were aggressors as well as targets of male aggression in a majority of encounters. Females were targets of male aggression in over half of encounters, while being aggressive in only a few of them. We describe three cases of male aggression towards immatures during male incursions, and one case of female transfer following one of these male]