title: The Behavioural Ecology of Indo-Pacific Humpback Dolphins in Hong Kong.
abstract: Fewer than 200 Indo-Pacific humpback dolphins (Sousa chinensis) occur in Hong Kong waters (though these are part of a much larger population in the Pearl River Estuary), with a decrease in the past about 10 years. They have partially overlapping individual ranges (mean=100km(2)), and two partially overlapping communities. Seasonal occurrence is higher in June-November than December-May, approximate wet and dry monsoon seasons, respectively. Group sizes tend to average three dolphins, a decrease from the past decade. Feeding often occurs in abruptly changing water depths and off rocky natural shores. The area immediately north of Hong Kong International Airport is largely used for travelling between locations to the west, east and further north. The area around Lung Kwu Chau Island in northwest Hong Kong is a "hot spot" for foraging and socializing. The area off Fan Lau, southwest Lantau Island, is largely used for foraging. A former foraging "hot spot" was located around the Brothers Islands east of the airport, now reduced, possibly due to increases in high-speed ferries (HSFs) and other activities. Sound recordings of dolphins from bottom-mounted hydrophones suggest that northwestern Hong Kong waters are used more at night than in daytime. Sexual activity and calving occur throughout the year, with a peak in late spring to autumn (wet monsoon season). Humpback dolphins communicate acoustically with each other and probably passively listen to prey in murky waters, and anthropogenic noises may be masking communication and affecting prey location. Increasing sounds of shipping, HSFs and industrial activities are likely to alter dolphin habitat use patterns and overall behaviours beyond the present already affected status.
authors.affiliation: Department of Marine Biology, Texas A&M University at Galveston, Galveston, Texas, USA. Electronic address: wursigb@tamug.edu.
authors.forename: Bernd
authors.initials: B
authors.lastname: Würsig
authors.affiliation: Department of Environmental Science & Policy, George Mason University, Fairfax, Virginia, USA.
authors.forename: E C M
authors.initials: EC
authors.lastname: Parsons
authors.affiliation: Department of Marine Biology, Texas A&M University at Galveston, Galveston, Texas, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Piwetz
authors.affiliation: SMRU Asia Pacific, University of St. Andrews, St. Andrews, Scotland.
authors.forename: Lindsay
authors.initials: L
authors.lastname: Porter
mesh_terms: D063147:Animal Distribution; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D002940:Circadian Rhythm; D003247:Conservation of Natural Resources; D004289:Dolphins / Q000502:physiology*; D017753:Ecosystem; D056727:Endangered Species; D006723:Hong Kong; D006802:Human Activities; D009043:Motor Activity; D012767:Ships; D012919:Social Behavior; D055871:Tidal Waves
keywords: Anthropogenic; Behaviour; Boat traffic; Ecology; Feeding; Habitat; Human disturbance; Indo-Pacific humpback dolphin; Interactions; Sousa chinensis