Abstract
During winter, dusky dolphins (Lagenorhynchus obscurus) were observed in coordinated diving apparently in a feeding activity, contrasting with the surface feeding observed during summer. The aim of this work consisted in analyzing the diving activity as an alternative foraging strategy in Argentine dusky dolphins, based on sequential analysis. The study area was Golfo Nuevo, located in Northern Patagonia, Argentina. Random transects were surveyed by a research boat from 2001 to 2007. During behavioral sampling, group members were observed continuously and the predominant activity was recorded at 2-min intervals. Six predominant activities were identified. Each 2-min interval was classified according to the activity at the previous interval (preceding activity), the activity at the interval (following activity), and the season (cold or warm). Z scores were calculated and then used to construct sequence diagrams. An association between diving and milling behavior was observed. This could be another foraging tactics different to the surface foraging sequences and this could be related with the distribution or abundance of preys.
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Acknowledgments
This research received logistic and institutional support from Centro Nacional Patagónico (CONICET) and the University of Patagonia. Funds were received from Agencia Nacional de Promoción Científica y Tecnológica (PICT No 01-4030, PICT No 11679 and 33934), CONICET (PID 320/99), Fundación BBVA BIOCON 04, Project PNUD ARG-02/018 (B-B27) and Fundación Vida Silvestre Argentina. Fieldwork was assisted by Hydrosport SRL, J. Owen and volunteers from Universidad de la Patagonia (Argentina) and Universidad de la República (Uruguay). We thank the anonymous reviewers, who provided many constructive comments, which much improved this manuscript. This work was carried out under permits of the Dirección de Fauna y Flora Silvestre and Secretaría de Turismo de la Provincia de Chubut. M.D. and G.V.G. were supported by a Ph.D. Fellowship from Consejo Nacional de Investigaciones Científicas y Técnicas of Argentina.
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Degrati, M., Dans, S.L., Garaffo, G.V. et al. Diving for food: a switch of foraging strategy of dusky dolphins in Argentina. J Ethol 30, 361–367 (2012). https://doi.org/10.1007/s10164-012-0333-1
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DOI: https://doi.org/10.1007/s10164-012-0333-1