Regulation of Bellowing of Chinese Alligators (Alligator sinensis) in the Wild

The study of bellowing of Chinese alligators (Alligator sinensis) was carried out during the period of 2003 in Hongxing reservoir (30°46′N,118°41′E) of Xuancheng,Anhui,China.The reservoir contains a small group (8-10 individuals) of wild and reintroduced alligators.When the bellow was heard,we recorded the date,time and number of bellows,and the weather condition.The results showed that the Chinese alligator began to bellow in March,and ended in November.The bellowing varied markedly on an annual basis (χ2 test:χ2=448.29,df=8,P<0.01).The Chinese alligator bellowed most frequently in June,which accounted for 26.0% of the annual total.There was a significant different in the frequency of alligator bellowing between the reproductive period and non reproductive period (Mann-Whitney U test:U=2.0,P<0.05).The average number of bellows per month was 128 (SD=71.11,n=4) during the reproduction period,and it was obviously higher than that during the non reproductive period.The frequency of bellows also varied significantly on a diurnal basis (χ2=233.18,df=17,P<0.01) with two obvious peaks at 6:00-7:00 and 10:00-11:00.The frequency of bellows differed significantly between 06:00-18:00 and 18:00-24:00 (U=12.5,P<0.05),and it was inversely related to the alligators activity.We observed no effect of weather conditions on the frequency of bellowing.Those results indicate that the Chinese alligators bellowing has a close relationship with the reproductive behavior in the wild.The bellowing is believed to play an important role for attracting the opposite sex during the mating period,and has close relationship with females protecting their eggs and young in the hatching period.Moreover,the bellowing has the function of territorial protection and possibly defense of food-resources.