MEPS 436:245-256 (2011)  -  DOI: https://doi.org/10.3354/meps09251

ABSTRACT: Animal movement is a central topic in ecology, as movements are crucial to habitat selection, foraging and spatial population ecology. Movement is a primary mechanism coupling animals to their environment, as organisms respond to environmental heterogeneity at different spatio-temporal scales. The fjord system in southern Chile is highly heterogeneous and sustains poorly known dolphin species, including the sympatric Chilean Cephalorhynchus eutropia and Peale’s Lagenorhynchus australis dolphins. Focal dolphin group follows were undertaken between January and April 2007, 2008 and 2009 to assess the fine-scale movement patterns of these 2 species in southern Chile. Correlated random walk models (CRW) overpredicted dolphin paths for both species, indicating that dolphins displayed a resident type of movement. Only a small number of dolphin groups fitted a Lévy flight model, thus suggesting that dolphins undertake a non-random searching strategy. First-passage time (FPT) models for both species showed that dolphins spent a large proportion of their time in small localised areas of only 100 m radius. Generalized additive mixed models (GAMMs) demonstrated that Peale’s dolphin movements were highly associated with kelp beds while Chilean dolphin movements were associated with rivers. Movement patterns of both species are very similar in scale and form, but they differ in relation to the associated ecological features. Movement models may be useful for developing holistic and more realistic predictions of how dolphins may respond to shifting resources as a consequence of environmental change with clear implications for conservation.

KEY WORDS: Cephalorhynchus eutropia · Lagenorhynchus australis · Dolphin movement · ­Correlated random walk · Lévy flight · First-time passage · Generalized additive mixed models