Acoustic communication is widely used by animals. In this study, first systematic studies were carried out on acoustic signals, communication and their roles in reproductive ecology of Chinese alligator (Alligator sinensis) by using field observation, spectrographic analysis and playback experiment. The main results and conclusions of this study are summaried as follows:
1)Chinese alligators have an elaborate acoustic communication system with both long-distance signal and short-distance signals. The signal spectrographic analysis showed that the acoustic signals of Chinese alligators have a very low dominant frequency, less than 500 Hz. These frequencies are consistent with adaptation to a habitat with high density vegetation.
2)Bellowing is the most notable vocal behavior of Chinese alligators, they form bellowing choruses from May to October, while Comparing with non-mating season, it is notable that bellowing could congregate individuals inhabited far and near into the same pond during the mating season.
3)Playback experiments revealed that Chinese alligators may not bellow to compete for or attract mates during the choruses, they may
synchronize bellows to enhance group detectability for assembling more individuals into certain waters for subsequent copulations.
4)Playback experiments showed that Chinese alligators exhibited high tolerance to signal variations that relatively large modifications in
bellow temporal or frequency structure failed to impair their behavioral response, these might be an evolutionary adaptation to a lack of selection
pressure due to the low risk of incorrect conspecific recognition and heterospecific mating, as Chinese alligator has no relatives living in sympatry.