Dear all
We are happy to announce that the following paper is now published in
Journal of Biogeography.
Breeding status affects fine-scale habitat selection of southern right
whales on their wintering grounds.
William Rayment, Steve Dawson and Trudi Webster.
Journal of Biogeography 42: 463-474.
For a PDF please email [email protected]
*Abstract*
*Aim *To develop and validate a model for fine-scale distribution of
southern right whales (/Eubalaena australis/) on their calving grounds,
accounting for breeding status.
*Location *Port Ross, a harbour at the northern end of the sub-Antarctic
Auckland Islands, approximately 450 km south of mainland New Zealand.
*Methods *Species–habitat surveys were conducted during annual winter
expeditions to the Auckland Islands from 2010 to 2012. Presence
locations for groups including calves (calf groups; /n/ = 462) and not
including calves (non-calf groups; /n/ = 313) were recorded during
small-boat surveys of Port Ross, and an equal number of pseudo-absence
locations were generated in a GIS analysis. Explanatory variables tested
were water depth, seabed slope, distance to coast, distance to shelter
from prevailing wind and average wave exposure (estimated from a
custom-built wave model). The occurrence of calf groups and non-calf
groups was separately related to explanatory variables using binomial
generalized additive models, with best models chosen via the minimum
Akaike information criterion score. Multi-fold validation was conducted
to assess model performance and temporal variation in distribution.
*Results *The best models for calf groups were consistent, always
including wave exposure, distance to shelter, depth and distance to the
coastline. In contrast, the best non-calf group models were more
variable and explained only a small proportion of the variation in the
data. Validation metrics indicated that the calf group models were
useful predictors of distribution in Port Ross during winter, and that
the calf group models performed better than the non-calf models using
the same suite of environmental variables.
*Main conclusions *Breeding female southern right whales seek sheltered,
nearshore waters during the early life-stages of their calves and are
more selective of these habitats than non-calving whales. The results
highlight the importance of sheltered habitat for taxa with vulnerable
life-history stages, and the need to account for reproductive status to
refine species–habitat models.
--
Will Rayment, PhD
Lecturer
Marine Science Department
Te Tari Putaiao Taimoana
University of Otago
PO Box 56
Dunedin
New Zealand
phone: +64 3 4798304 (w) +64 21 488961 (mob.)
http://www.otago.ac.nz/marinescience/staff/willrayment.html
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