Some observations on the sociosexual behavior of a captive male Yangtze finless porpoise calf (Neophocaena phocaenoides asiaeorientalis)

Abstract

Sociosexual behavior in a captive male Yangtze finless porpoise calf (Neophocaena phocaenoides asiaeorientalis) was studied during its first year postpartum. This behavior was first observed at 1 month postpartum. During the year, (1) each event of the sociosexual behavior typically lasted 6–9 s and the frequency was 2.8 occurrences h−1; (2) ventral–ventral was the predominant sociosexual gesture; (3) prior to sociosexual interactions, the calf generally bonded with the receiver; (4) the mother was his preferred sociosexual partner but other adults of both sexes were also involved; (5) the frequency of sociosexual behavior decreased until the 9th month postpartum and increased thereafter.