Dear all,
We are pleased to announce our recent publication: "A new method to study inshore whale cue distribution from land-based observations" 1. Patricia Arranz, Sea Mammal Research Unit, University of St Andrews, Scotland and Department of Animal Biology, La Laguna University, Spain. 2. David Borchers, Centre for Research into Environmental and Ecological Modeling, University of St Andrews, Scotland. 3. Natacha Aguilar de Soto, Sea Mammal Research Unit, University of St Andrews, Scotland and Department of Animal Biology, La Laguna University, Spain. 4. Mark P. Johnson, Sea Mammal Research Unit, University of St Andrews, Scotland. 5. Martin J. Cox, Pelagic Ecology Research Group, Scottish Oceans Institute, University of St Andrews, Scotland. Author for correspondence: [email protected] SUMMARY The challenges involved in the visual detection of some cetacean species make it difficult to obtain information about their distribution and habitat preferences using traditional sampling methods. This is particularly the case for species such as beaked whales that spend a small amount of time at the surface and have inconspicuous surface behavior. The coastal waters around El Hierro (Canary Islands) hold year-round populations of two beaked whale species, Cuvier's (/Ziphius cavirostris/) and Blainville's (/Mesoplodon densirostris/), providing an ideal scenario to set up land-based point transect surveys to study the inshore behavior of these deep-diving species. This work extends traditional distance sampling methods to allow the distribution of animals seen from an observation point on the coast to be modeled with respect to a nonlinear environmental feature (water depth). Depth is a key factor delimiting marine habitats and is especially relevant for understanding the distribution of deep-diving species such as beaked whales, which approach the seafloor to feed. Our model predicts the highest density of beaked whale cues around the 1,000 m isobath and most (90%) of beaked whale groups surfacing in waters with seabed depths between 325 and 1,660 m depth. The distribution of the sightings suggest that the habitat selection of both species is probably driven by an increased prey availability on the slope of the island. Because the number of sightings at a given depth is not necessarily proportional to the number of groups present, in this particular case additional information on surfacing rates, and how they vary with depth, will be required to draw inferences about animal distribution. We conclude that this method is useful to investigate the distribution and habitat selection of animals in relation to environmental variables using observations from land and that future development work will allow covariates in the detection function or multiple environmental features to be considered when implementing density estimates. The pdf can be downloaded from here: _http://onlinelibrary.wiley.com/doi/10.1111/mms.12077/abstract_ Or a pdf copy can be obtained upon request to: [email protected] <mailto:[email protected]>_ Patricia Arranz, Ph. D. Sea Mammal Research Unit Scottish Oceans Institute School of Biology University of St Andrews St Andrews KY16 8LB Scotland --- Este mensaje no contiene virus ni malware porque la protección de avast! Antivirus está activa. http://www.avast.com
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