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Wendy Schrader

Doctor of Philosophy, (Ecology)
Study Completed: 2013
College of Sciences


Thesis Title
Comparative socioecology of the dusky dolphin (Lagenorhynchus obscurus) in New Zealand

Read article at Massey Research Online: MRO icon

Behaviour and social groupings of animals are often closely tied to habitat structure.  This study examined the socioecology of dusky dolphins off Kaikoura.  Behavioural data were collected from 332 dusky dolphin and 67 Hector’s dolphin groups during 2006-2009.  In winter, dusky dolphins formed large, wide-ranging groups.  In summer, small groups formed for calf-rearing, mating and resting. Groups with calves were the largest and most socially stable.  Mating groups had rapid chases with competition among males for access to females.  Hector’s dolphins formed smaller, less socially stable groups, with fewer social behaviours than dusky dolphins.   Resting was disrupted during tour interactions with dusky dolphins and dolphins travelled away from tours.   Assertive tour approaches reduced the duration of swimmer-dolphin interactions, particularly in summer when dolphins may be sensitised to high levels of tourism.   These large-brained, social mammals form intricate societies that respond to changes in predation pressure and prey availability.

Professor Doug Armstrong
Professor Bernd Wursig