Dusky dolphin nursery groups off Kaikoura, New Zealand

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Title: Dusky dolphin nursery groups off Kaikoura, New Zealand
Author: Weir, Jody Suzanne
Abstract: The distribution , behaviours , and composition of dusky dolphin (Lagenorhynchus obscurus ) nursery groups off Kaikoura , New Zealand , were examined . Data were collected during January ?May 2005 and December 2005 ?April 2006 by systematic boat based surveys , group focal follows and photo -identification techniques . A total of 99 nursery groups were encountered on survey . Nursery groups were encountered in shallow water ( <20 m ) significantly more often than in deeper water ( >20 m ) . Other group types (large groups , mating groups , adult non -mating groups ) were not found in shallow water significantly more often than in deeper water . By staying in the shallower water , nursery groups may be protected from aggressive conspecifics and predators . More boats , especially private recreational boats , were found in the shallower waters , indicating that nursery groups are at greater risk from encounters with boat motors or recreational fishing gear in such areas . Group focal follows of at least 30 - minutes were conducted on 56 nursery groups . Calves engaged in significantly more high energy behaviours (displays and head first re -entries ) than non -calves in nursery groups . These groups were predominantly resting and compactly organized (interanimal distance less than 1 adult body length ) . Nursery groups showed a high level of synchrony , with 44 % of groups synchronizing their submergence and surfacings for most of the focal follow . Median group size was 14 , with a minimum of 2 mother -calf pairs to a maximum of 50 mother -calf pairs . A total of 260 individuals were catalogued as members of nursery groups during the two field seasons . Of these , 112 individuals were seen in nursery groups on at least two different days . Some individuals photographed with young calves in nursery groups off Kaikoura were later photographed in Admiralty Bay , 275 km northwest of Kaikoura . Other individuals photographed together in nursery groups in 2005 were also together in nursery groups in 2006 .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -1394
Date: 2009-05-15

Citation

Dusky dolphin nursery groups off Kaikoura, New Zealand. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -1394 .

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