Fission-fusion sociality in dusky dolphins (Lagenorhynchus obscurus), with comparisons to other dolphins and great apes

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Title: Fission-fusion sociality in dusky dolphins (Lagenorhynchus obscurus), with comparisons to other dolphins and great apes
Author: Pearson, Heidi Christine
Abstract: I examined fission -fusion sociality in dusky dolphins (Lagenorhynchus obscurus ) , and investigated aspects of social convergence between dolphins and great apes . I used boat -based group focal follows and photo -identification to collect data in Admiralty Bay , New Zealand during 2005 -2006 . I used generalized estimating equations to examine relationships between party (group ) size , rate of party fission -fusion , activity , and location ; and relationships between leaping frequency and behavior . Using photo -identification images from 2001 -2006 , I analyzed the strength and temporal patterning of associations , short - and long -term association patterns , preferred /avoided associations , and behaviorally -specific preferred associations . To analyze social convergence between dolphins and great apes , I compared female bottlenose dolphin (Tursiops spp . ) and chimpanzee (Pan troglodytes ) social strategies through literature review . I conducted 171 group focal follows , totaling 157 observation hours . Mean party size was 7 .0 ?6 .0 individuals . Party size changed every 5 ? .47 .6 min on average . The most frequent activity was resting (37 % ) , followed by traveling (29 % ) , foraging (18 % ) , and socializing (15 % ) . Foraging was positively related to party size and rate of fission -fusion . Near mussel farms , foraging increased , traveling decreased , and rate of party fusion increased . "Clean" leaps were the most frequent leap type (84 % ) and were positively related to party size and foraging . Noisy and coordinated leaps were positively related to party size ; noisy leaps were negatively related to foraging . Associations during 2001 -2006 (N = 228 individuals ) were nonrandom for 125 days ; associations within one field season were nonrandom for 60 days . Individuals formed preferred /avoided associations during most years . The strongest associations occurred during foraging and socializing ; the weakest associations occurred during traveling . Individuals formed preferred associations during foraging , resting , and socializing . Review of female bottlenose dolphin and chimpanzee sociality revealed that : 1 ) females form weaker bonds and are less social than males , 2 ) females associate mostly with other females , 3 ) mothers are often alone with their offspring , 4 ) mothers (vs . non -mothers ) and non -cycling (vs . cycling ) females associate less with males , and 5 ) non -cycling (vs . cycling ) females occur in smaller parties . Female dolphins may be more social than female chimpanzees due to decreased scramble competition , increased predation risk , and decreased cost of transport for dolphins vs . chimpanzees .
URI: http : / /hdl .handle .net /1969 .1 /86073
Date: 2008-10-10

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Fission-fusion sociality in dusky dolphins (Lagenorhynchus obscurus), with comparisons to other dolphins and great apes. Available electronically from http : / /hdl .handle .net /1969 .1 /86073 .

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