Abstract
Most delphinids are very social and spend much time in the presence of conspecifics. The proportion of co-occurrences of any two individuals is usually measured by means of association indices. In this study, the "half-weight index" was used to describe the association patterns in three previously unstudied populations of Hector's dolphin, Cephalorhynchus hectori, around the South Island of New Zealand. For inclusion in this analysis individuals were photoidentified repeatedly over a 2-year study period. Only about 1% of the individual associations of dolphin pairs (dyads) tested were found to be significantly different (p less than or equal to 0.01) from random distributions derived from a new constrained Monte Carlo randomisation. The overall association patterns in the two study populations off Kaikoura ( n = 48 individuals) and Moeraki (n = 24) did not differ significantly from what could be expected by chance (p = 0.07 and 0.09, respectively), whereas those in the Jackson Bay population (n = 38) were significantly different from chance (p < 0.0002). Hector's dolphins appear to have a typical fission-fusion society, with many weak associations within the wider envelope of the local population.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.