Authors: VIGNESS-RAPOSA , Kathleen, University of Rhode Island

Abstract: Technological advances have increased the potential to understand broad scale ecological processes that influence biologically significant behaviors. Humpback whales (Megaptera novaeangliae ) in the North Atlantic Ocean migrate to genetically and spatially distinct feeding aggregations each summer. The environmental features that drive this matrilineal site fidelity have been examined on individual feeding grounds, but a comprehensive evaluation of the habitat preferences of humpback whales throughout the North Atlantic has not been conducted. Summer sightings of humpback whales in the Gulf of Maine, eastern Canada, and Iceland were analyzed with temporally dynamic environmental variables and spatially static geographic variables to build models to predict habitat preferences. Models were constructed using logistic regression and geostatistics to determine significant variables and estimate spatial parameters, respectively. Twelve models were created based on a priori ecological hypotheses and results from previous studies of individual feeding grounds. The model that explained the greatest amount of variability included all considered variables (month; year; depth; slope; distance from shore, 100-m isobath, 200-m isobath; sea surface temperature (SST); and SST gradient), although the R2 value was only 0.17. Examining the data more closely, the variable “region,” which identified the feeding ground in which the sighting occurred, was significant (P < 0.001). After building site specific models, the explanatory power increased from R2 = 0.30 for Iceland to R2 = 0.38 for the Gulf of Maine. Interestingly, the model that explained the greatest amount of variability in each feeding ground again included all considered variables. In all three regions, the variables slope and SST had large coefficients, greatly influencing the habitat models. Humpback whales appear to prefer regions close to shore and the 100-m isobaths with cool temperatures and steep bathymetric relief.