On The Behavior And Acoustic Observation Of The Yangtze Finless Porpoise

The present dissertation consists of two parts. The first part is on dominance relations among captive Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis) and male mating tactics; and the second part is on diel variations in diving and echolocation behaviors of captive porpoises, and the passive acoustic monitoring method applied to observation and group size estimation of porpoises in semi-natural waters.Focal-animal and continuous sampling schemes were employed to observe the captive porpoise colony consisting of 3 to 6 individuals in Wuhan Baiji Dolphinarium from 2000 to 2002, and a total of 136 hr of behavioral data was recorded. The dominance relations among porpoises and male mating tactics were analyzed quantitatively. Dominance relations among the same gender individuals were age-ordered, and the older porpoises were dominant to the younger ones; however, the dominance relations among cross-gender individuals were changeable even if the individuals were very different in ages. The adult female might be the founder of a core group of porpoise, whereas the male might rove among core groups. The mating tactics of the male porpoise might be to copulate frequently with some other females while maintaining a close bond with one female. The erection behavior of male porpoise occurred all the year, but the peak months of copulation might be from April to June, and September.Diving behavior and echolocation pulse rate of three captive porpoises in Wuhan Baiji Dolphinarium were observed continuously using both behavioral and acoustic data loggers on 23?25 November 2002. A total of 38 hr of behavioral data and 40 hr of acoustic data were recorded for each porpoise. Diel variations in diving duration, swimming speed and sonar emission rate were analyzed for the porpoises. The porpoises usually dived longer and swam slowly at night in comparison with what they did during the day. The individuals might be inactive or at rest at night, and they might decrease sonar pulse emission during the period of time. Additionally, the decrease in human activities at night might cause the decrease in emission of echolocation signals of captive porpoises.Group size and movement direction of the porpoises were monitored acoustically using twin arrays of acoustic data loggers in semi-natural waters in 2003and 2004, and a total of 72 hr of visual and acoustic observation data was obtained in 9 days. The stationed passive acoustic observation method was effective in both detecting presence and determining movement directions of porpoises, and showedpotential in estimating the group size. The acoustic data logger arrays could detect the presence of porpoises with a correct detection of 77.6% and a false alarm of 5.8%; and could determine the movement direction of porpoise with a correct detection of 60.0%.Results of the present study could be considered as references of reproduction researches and improvement of ecological observation methods of the Yangtze finless porpoise.