CLASSIFICATION OF WEDDELL SEAL DIVING BEHAVIOR

Most studies of pinniped diving behavior have manually grouped dives a ccording to similarities in the depth, duration, and appearance of the dive profile. Dives of 15 adult female Weddell seals (Leptonychotes w eddellii) were recorded with time-depth recorders and 39,119 dives wer e classified manually and statistically (principal components analysis , discriminant function analysis, duster analysis, and shape-fitting a lgorithms). Four dive types, common to all classification methods, and a fifth dive type, common to two of the methods, represented most of the observed diving behavior. However, a few variations of these dive types, specifically a flat-bottomed dive determined manually, may have also represented important behavior. Using a combination of these met hods, all dives were classified into six dive types. Inspection of div e variables (mean maximum depth, mean duration, and frequency) over ti me for each dive type, as well as comparisons to previous studies of p inniped diving behavior, indicated different behaviors that the dive t ypes may represent. Hypothesized functions for the dive types were pel agic foraging, benthic foraging, exploration, and traveling. The resul ts indicate that there are strong similarities in diving behavior acro ss various phocid species, that statistical analyses of diving behavio r ate useful in the analysis of a large data set, and that these analy ses reduced human subjective bias in interpreting diving behavior.