The laboratory population was founded by the cross-fostering method. In order to investigate mechanisms of kin recognition by odor cues, we observed the behavioral responses of adult male root voles ( Microtus oeconomus
) to urine odors from females, which include non-siblings reared together (NSRT), non-siblings reared apart (NSRA), and siblings reared apart (SRA). The results showed that there are no significant differences in male vole body weight between siblings reared together and SRA during different developmental periods (age 2-70 days). Approach latency by males was significantly longer in response to NSRT than NSRA, whereas visiting time and sniff time by males were significantly shorter in response to NSRT than NSRA opposite-sex conspecifics. The behavioral responses of males to urine odors from SRA and NSRA had no relationship with the degree of genetic relatedness. In conclusion, male root voles 80 days in age can discriminate between familiar and unfamiliar non-kin by urine cues, but such males cannot discriminate between unfamiliar kin and non-kin. We conclude that male voles use an odor association mechanism for sibling recognition.