Abstract:
Focal-animal sampling techniques developed for investigating social behaviour of
terrestrial animals were adapted for studying captive belugas, providing quantitative
descriptions of social relationships .among individuals. Five groups of captive belugas
were observed, allowing a cross-sectional view of sociality in groups of diverse sizes and
compositions.
Inter-individual distances were used to quantify patterns of spatial association. A set of
social behaviours for which actor and recipient could be identified was defined to
characterize dyadic interactions. The mother-calf pair spent more time together, and
interacted more often than adults. The calf maintained proximity with his mother; larger
adults generally maintained proximity with smaller adults. Among adults, larger groups
performed more kinds of behaviours and interacted at higher rates than smaller groups.
Within dyads, the larger whale performed more aggressive behaviours and the smaller
whale more submissive behaviours. Clear dominance relations existed in three groups,
with larger whales dominant to smaller whales.
Vocalizations of three groups were classified subjectively, based on aural impressions and
visual inspection of spectrograms, but most signals appeared graded. Statistical analyses
of measured acoustic features confirmed subjective impressions that vocalizations could
not be classified into discrete and homogeneous categories.
