| Chinese alligator(Alligator sinensis) belongs to Family Alligatoridae, Order Crocodylia, and Class Raptilia. The species has been only in China, and was declared a Class - 1 protected species by Chinese Government in 1972. During the last tens of years ,due to the fragmentation and isolation of the Chinese alligator habitant, and human protection and other negative influences, its distribution area shrinks rapidly ,and the wild Chinese alligator have been almost become extinct. The wild alligator population is less than 130 individuals, and the species is in severe danger. Moreover, the population has been evidently divided into 18 isolated small local populations with different amounts individually. So Chinese alligator have been listed as the top priority species of the 23 kinds of globally protected alligators by the expert team of IUCN' s alligator Protection Program. To rebuilt the effective wild population to avoid depopulation of the wild Chinese Alligator. It is suggested to resume habitant large enough and to release alligators in them to reestablish effective wild population.In this paper we consider all populations of wild Chinese Alligator in existence as a single one. we predict the population dynamics of wild Chinese Alligator in 50 years with the help of Vortex model 7.3 . And a study of the bellowing of wild Chinese alligator was carried out in Hongxing reservoir (30?6'N , 118?1'E) of Xuancheng in Anhui province ,P.R China from March to December, 2003. The results are following:1 )The recent population dynamic is insensitive to inbreeding depression, variety of carrying capacity but very sensitive to catastrophes. Even under the ideal condition (with no catastrophe and no inbreeding depression),the population dynamic is only maintained steadily ; but It will increase the population size significantly with the supplementation of raised alligators regularly; and supplementation of raised alligators regularly on the basis of resuming habitant large enough is more significant, the population number maintained is quite related to mean size of outside supplementation of culture Chinese Alligator.2) Bellowing varied markedly on an annual basis ( x2 test, x2=448.29, df= 8, p< 0.01, n=9). Chinese alligator bellowed most frequently in June, which ccounted for 26.0% of the annual total. There was a significant different in the frequency of alligator bellowing between the reproductive period and non reproductivepenod(Mann-Whitney Utesl,p<0.05 ). The average number of bellows per month was higher during the reproduction period was 128 (SD=71.11 , n=9), and it was obviously higher than that of the non reproductive period. The frequency of bellows also varied significantly on a diurnal basis ( x2 test, x2=233.18, df=17, p <0.01, n=18), with two obvious peaks at 6: 00~7: 00 and 10: 00 ~ 1 1 : 00. The frequency of bellows by Chinese alligator's differed significantly ( Mann-Whitney U test,p<0.05 ) between 06:00-18:00 and 18:00~24:00, The frequency of bellows is inversely related to the activity of the alligators. We observed no effect of weather conditions on the frequency of bellowing. These results indicate that Chinese alligator's bellowing has a close relationship with their reproductive behavior in wild. The alligator's bellowing is believed to play an important role for attracting the opposite sex during the mating period, and has close relationship with female Chinese alligator's activities of protecting eggs and young ones in the hatching period . Moreover, their bellowing has the function of territorial protection and possibly defense of food- resources.
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