Community Structures And Behavioural Ecology Of Indo – Pacific Humpback Dolphins (Sousa Chinensis) In Cowie Bay, Sabah, Malaysia

Abstract

Little is known about the Indo-Pacific humpback dolphins that inhabit Cowie Bay, Sabah. Therefore, this project is expected to provide scientific information on Indo-Pacific humpback dolphin‘s group size, social structure and residence patterns in Cowie Bay, Sabah. Boat based surveys were conducted from April 2008 to March 2009 to evaluate the status of humpback dolphins using two methods; Peterson capture-recapture method (using photo identification) and direct count method. Data were analysed using statistical software and Microsoft Photo Manager. Results showed that the humpback dolphin’s community was small. Only three individuals were identified and catalogued living in the bay within 1.8 – 25 meters depth of water. The sighting rate was higher during neap tides than during spring tides. However, the group size (Mean = 2.49) was not affected by the different types of tides (U = 250.5, p > 0.05, r = -0.12). The community was recorded to be socially active in the afternoon compared to morning and evening. The analysis showed that the percentage for the individuals to be seen together was 48.8%, and the range of 9 – 12% observed to be solitary sightings. The association indices between individuals suggested that the community is highly associated with each other (AI = 0.6373 / 0.5756 / 0.6728).