Maldini, Daniela and Nilsson, Peter (2001) Social ecology of bottlenose dophins in Monterey Bay, California. In: The Society for Marine Mammalogy -14th Biennial Conference , 28 November - 3 December 2001 , Vancouver, British Columbia, Canada.
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Abstract
Between 1990 and 1995, Pacific coastal bottlenose dolphins (Tursiops truncatus gillii) were studied using photo-identification during 228 boat-based surveys of the coastal strip (<1 km offshore) between Marina and New Brighton Beach in Monterey Bay (18 km of coastline). The study period encompassed 3 regular (1990, 1991 and 1995) and 3 El Niño years (1992, 1993, 1994). Based on dorsal fin markings, 97 unique individuals were identified. Eighteen animals (19%) showed a high level of site fidelity (defined as presence in at least 5 of the 6 years), although their overall range was larger than the study area. Thirty-eight animals (39%) were transient, leaving for periods of time, and 41 (42%) were occasional encounters. The rate of discovery indicated a pulsed recruitment of new individuals into the study area, with periods of stable school composition, especially during non-El Nino years, and periods of high school fluidity. Encounter rate was significantly higher in El Niño (81%) than non-El Niño years (61%). School size averaged 16 individuals (C.I.3, =0.05) and was significantly larger in El Niño years. Schools where calves were present were twice as large (mean=15; S.D.=8) than schools without calves (mean=8; S.D.=6). Newborns represented 12% of the sightings and were seen year round with a peak in summer and fall. Crude birth rate ranged between 0.09 and 0.17 (mean=0.13; S.D.=0.03). Five females calved in consecutive years and a resident female calved once a year for the duration of the study, possibly indicating a high rate of mortality for calves in this area. Individuals often traveled as subgroups of more consistent composition than the school itself, possibly indicating that a stronger social bond exists within these units which may function as “bands” (sensu Wells 1991) of same sex individuals traveling within a larger school of mixed composition. (ppt file of poster)
| Item Type: | Conference or Workshop Item | ||||||
|---|---|---|---|---|---|---|---|
| Title: | Social ecology of bottlenose dophins in Monterey Bay, California | ||||||
| Personal Creator/Author: |
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| Refereed: | No | ||||||
| Page Range: | p. 1 | ||||||
| Date: | 2001 | ||||||
| Contact Email Address: | dmaldini@okeanis.org | ||||||
| Event Title: | The Society for Marine Mammalogy -14th Biennial Conference | ||||||
| Event Type: | Conference | ||||||
| Event Location: | Vancouver, British Columbia, Canada | ||||||
| Event Dates: | 28 November - 3 December 2001 | ||||||
| Subjects: | Ecology Biology Environment | ||||||
| Item ID: | 2670 | ||||||
| Depositing User: | Dr Daniela Maldini | ||||||
| Date Deposited: | 26 Oct 2009 14:09 | ||||||
| Last Modified: | 09 Dec 2010 10:59 | ||||||
| URI: | http://aquaticcommons.org/id/eprint/2670 |
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