Social–sexual behavior seasonality in captive beluga whales ( Delphinapterus leucas )

Observation of wild beluga whales (Delphinapterus leucas) indicates that this species breeds seasonally, and hormonal assays of captive animals show corresponding fluctuations in reproductive hormones. The question remains, however, whether copulatory behavior itself occurs seasonally. As an index of copulatory behavior, data are reported here on the frequency with which pelvic thrusting occurs over the calendar year. Male-on-female thrusting did vary significantly across months, with a clear peak in activity in March. On the other hand, male-on-male pelvic thrusting did not differ significantly across months. Possible functional roles are suggested for this latter enigmatic behavior.