Shark Bay Dugongs in Summer. I: Lek Mating

Abstract

AbstractIn a shallow sparsely vegetated cove in eastern Shark Bay, Western Australia, approximately 20 solitary dugongs occupied small mutually exclusive zones of activity in the springs of 1988 and 1989. Occupants of those activity zones bordering on shoal areas patrolled their zones, defended them against intruders, and engaged in unique activities (bottom swims, situps, and belly-ups) which appeared to be intrasexual and/or intersexual displays. Forage biomass in the cove was inadequate to meet dugong maintenance requirements and known or presumed females appeared only in contexts implying mating. I infer that all residents of the cove were male. Sexual activity observed in this cove contrasted with the 'mating herd' pattern reported for sirenians elsewhere in that courtship and mating occurred in a pair context, a presumed female was herded within an exclusive territory, females were not harassed by groups of males, and apparent copulation occurred without persistent interference or harassment by additional males. I believe the cove is a traditional arena where an aggregation of males on display territories meets all the requirements of a classic lek.