This research analyzed the effects of quinestrol and/or levonorgestrel treatment on enclosed Brandts vole populations.In 2008,7 groups of captive voles were held in a 10m×10m enclosure respectively,and animals were orally gavaged with 20mg/kg quinestrol and levonorgestrel in maize oil daily for 14 days.Treatments (n=3 replicates each) were applied to either males or females in an enclosure (33%,66%and 100%) ,plus there was an untreated control group.In March 2013,2 mg/kg quinestrol only was delivered by oral gavage for 10 days to 72%male and 68%female Brandts voles in a population enclosed in 100m x 100m.Population density and the structure characteristics were monitored from May to October using capture-mark-recapture method.In 2013,social behaviors of normal and treated animals were recorded using digital video.Results showed more than 1/3 males Brandts voles needed to be sterilized to reduce the population density significantly in the enclosure,but a higher ratio of sterilization of females was required to cause a similar decrease in population size.The one-off contraceptive treatment of 70%Brandts voles (both sexes) in an enclosure population suppressed numbers compared with a control population within 2 months.There were no differences in either dispersal frequency (P=0.6608) ,dispersal distance (p=0.9594) ,or social behaviors (including attack,agonistic,sniffing,contact and mating ones) between sterile and fertile individuals.These results demonstrate that quinestrol has minimal behavioral side effects on Brandts voles,which may be a useful fertility control agent for the management of Brandts vole populations.