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Chinese white-bellied rats,Niviventer confucianus,were mark-recaptured from July to November,2009 and from March to November,2010 on two islands of the Thousand Island Lake region.The maximum movement distances of Chinese white-bellied rats that were recaptured 4 or more times were calculated in spring,summer and autumn by Biotas 2.0.Then we used independent sample T test,one-way ANOVA or Mann-Whitney U test to analyze the effects of age,sex and season on the maximum movement distance.We aim to explore movement and home range of Chinese white-bellied rats in isolated island environment,and to predict its behavioral responses to isolated island environment.The results showed that there was no significant difference in the maximum movement distance between two islands,and the data of the two islands could be pooled.There were highly significant differences in the maximum movement distance among four different age groups.The maximum movement distance of males was significantly longer than females in adults,but did not differ between the sexes in any other age groups.The maximum movement distance differed significantly among spring,summer and autumn in sub-adults,but not in other age groups.The maximum movement distance of both males and females was longest in autumn and shortest in spring.Our results indicate that the maximum movement distance is positively correlated with the age of Chinese white-bellied rats,and is significantly longer in males than females.Our results were inconsistent with some of the previous studies on home range size in rats.This inconsistency likely reflects the restriction of resources in isolated island environment and specificity of behavior in Chinese white-bellied rats.This study preliminarily displays the effects of island isolation on small mammals,and more studies are needed to examine the island effects in the future.

We live-trapped two Niviventer confucianus populations from October 2009 to November 2010 in Thousand Island Lake region using the capture-mark-recapture(CMR) method,and studied the age structure and sex ratio of the populations.Then,we discussed the impact of habitat fragmentation on the population structure of Niviventer confucianus.Our results showed that the dominant groups included juvenile group and sub-adult group in the first half of the year,while they changed into the adult group and old-adult group after half the year.It was different in the influence on the age structure of Niviventer confucianus between the land-bridge island and terrestrial environment.The juvenile group began to appear in October and November,and the high proportion of juvenile group was in March and April.So the population growth reached the peak in the first half of the year.Because of Aging,the population eventually declined after half the year.There was significantly negative correlation between the population quantity and sex ratio.When the population sizes reached the peak,the number of females was less than that of males.Nevertheless,when the population sizes were low,the number of females was more.We considered that in the process of population growth,the females were more important than males.This may be a performance of the internal adjustment mechanism of population dynamics of Niviventer confucianus.The predation risk is one of the main factors to affect the sex ratio.The wild boar may lead to the fewer males in June in B island.The average litter size of Niviventer confucianus in medium-sized island was significantly higher than that in Jinhua region from September to October.Because of the high breeding rates in September and October,February and March,the population reached to a higher level in the first half of the second year.

We live-trapped two Niviventer confucianus populations from March to November of 2010 in Thousand Island Lake region using the capture-mark-recapture(CMR) method.We used Jolly-Seber method,modified Lincoln index method,Schnabel method and minimum number of animals alive(MNA) method to estimate population sizes of Niviventer confucianus,and discussed the applicability of these estimators in white-bellied rats on land-bridge island.Our results showed that there was no significant difference between Jolly-Seber method and modified Lincoln index method.We considered that modified Lincoln index method was more suitable for estimating the population quantity of Niviventer confucianus in the land-bridge island.The study can provide basic data for the future study of population ecology of rodent in the land-bridge island.