Dwarf sperm whales, Kogia sima, are among the most commonly stranded yet least known pelagic cetaceans. I assessed seasonal and spatial variation in dwarf sperm whale group size and abundance off Great Abaco Island, the Bahamas. After correcting for survey effort and variation in sighting efficiency among sea states, I found that dwarf sperm whale group size and habitat use varied seasonally. In summer, dwarf sperm whale groups were small (median = 2.5, range = 1-8) and were found only in the two deep habitats within the study area (slope 400-900 m, deep 900-1600 in). In winter, group sizes increased (median = 4, range = 1-12) and sightings were almost six times higher in the slope habitat, where vertical relief is highest, than other habitats. My results suggest that studies of pelagic cetaceans and conservation plans must explicitly account for seasonal variation in group size and habitat use.
