Ethogram of Yangtze finless porpoise calves (Neophocaena phocaenoides asiaeorientalis).

Underwater behavioral patterns of one Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) calf in captivity and those performed on the water surface by two calves in semi-natural environment were focally followed and continuously recorded until one year postpartum to construct the ethogram. The results indicate that 1) the three calves could display diverse and active behavioral patterns; 2) soon after birth, patterns critical for survival appeared first; 3) playful and social patterns predominated the ethogram; 4) most of the patterns were alike across age classes; 5) most of the patterns appeared at the calves' early life stage. It is possible that the above characteristics are adaptively shaped by the aquatic and social life of this subspecies.

Variation in sexual behaviors in a group of captive male Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis): motivated by physiological changes?

Most male mammals in temperate regions demonstrate seasonal sexual behaviors that coincide with seasonal variations in gonadal activities and androgen hormones. The Yangtze finless porpoise is a temperate freshwater cetacean species and an obvious seasonal breeder. To investigate the relationship between sexual behavior and gonadal activity in this animal, testicular size (volume) and structure (ultrasonogram pixel intensity) of two adult male porpoises (AF, AB) and one sub-adult male (TT) were longitudinally monitored from November 2008 to November 2009.