Surface Behaviours of Humpback Whale Megaptera novaeangliae at Nosy Be (Madagascar)

The surface behaviours of humpback whales were studied in the presence of a whale-watching vessel at Nosy Be (Madagascar) during whale-watching activities, in order to characterise the ethogram of these animals. Data were collected from July to October 2018. Of the 75 total trips, humpback whales were observed 68 times and different types of aggregations were observed: Groups (33.82%), Mother-calf pairs (30.88%), Singles (27.94%), and Mother-calf and Escorts (7.35%). Individuals exhibited the following behaviours: Spouting, Breaching, Head Slap, Tail Throw, Tail Slap, Peck Slap, Spy-hopping, and Logging. Sighting data were evaluated by comparing the observed aggregations with reported behaviours, and vice versa. Among the most commonly observed behaviours, Spouting and Peck Slap were exhibited more in Groups, while Breaching was exhibited by all of the associations, with the exception of Singles. In Groups of more than two individuals, little or no social nor aggressive behaviours were observed, probably due to a lack of needing to attract the attention of other individuals. This suggests that, during the breeding season, Nosy Be could represent a wintering and weaning ground for calves.