Eder E.B.,Centro Nacional Patagnico |
Lewis M.N.,Centro Nacional Patagnico |
Marn M.R.,Centro Nacional Patagnico |
Campagna C.,Centro Nacional Patagnico |
Campagna C.,Wildlife Conservation Society
Journal of Mammalogy | Year: 2011
The shallow Patagonian Shelf off Pennsula Valds limits the dive depth of southern elephant seals (Mirounga leonina) to <100 m, an unusual circumstance for this deep-diving species. Beyond the shelf water depths of >1,000 m enable the seals to forage deeper and use the entire water column. We compared the diving pattern of 10 juveniles instrumented with lighttemperature loggers to determine if diving effort, measured as dive durations longer than the estimated aerobic dive limit, differed between on-shelf and off-shelf waters. The productive Patagonian Shelf, an environment where juveniles showed lower diving effort, also was used commonly by older seals, which likely displaced juveniles off-shelf periodically, where they exhibited increased diving effort. © 2011 American Society of Mammalogists.
Garaffo G.V.,Centro Nacional Patagnico |
Garaffo G.V.,Brown University |
Dans S.L.,Centro Nacional Patagnico |
Dans S.L.,Brown University |
And 7 more authors.
Journal of Mammalogy | Year: 2010
The use of habitat selection models to predict the likely occurrence of wild populations is an important tool in conservation planning and wildlife management. The goal of our study was to build habitat selection models for the dusky dolphin (Lagenorhynchus obscurus) in Golfo Nuevo, Argentina. Random transects were surveyed by boat in 20022007. A grid of 1.5 × 1.5-km squares (cells) was constructed for the study area. We characterized each cell by depth, slope, distance from shore, sea-surface temperature, concentration of chlorophyll a, presenceabsence of dolphins, and a coefficient of use by dusky dolphins. Models were developed for warm and cold seasons and for all data combined. Data collected during 20022005 were pooled to develop the model, and data collected during 20062007 were used for cross-validation. Logistic regression with a binomial error structure and a logit-link function were used to relate the presence of dolphins to habitat variables. Models with gamma structure and log-link function were used to relate area use to habitat variables. Models were selected with deviance analysis and Akaike's information criterion. All predictor variables significantly influenced distribution of dolphins, which preferred steep areas at depths of 5060 m, distance from shore of 35 km, and higher values of chlorophyll. In the warm season dolphins preferred colder waters and avoided deeper and warmer areas. Dusky dolphins in Golfo Nuevo are exploited as a tourism resource, and selected models should be considered when deciding the impact of dolphin-watching activities on management. © 2010 American Society of Mammalogists.