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Social structures of different mongoose species of Family Herpestidae vary greatly from being solitary to social. Some solitary mongooses have been observed to have complex social interaction than expected. To understand the social structure of the crab-eating mongoose (Herpestes urva), which was categorized as a solitary mongoose, I conducted mark-recpture, radio-tracking and genetic analysis using microsatellite markers to examine spatial distribution and relatedness of individuals, dispersal pattern of male and females, and mating system of the species. From April 2008 to September 2009, I captured 22 crab-eating mongoose (10 males and 12 females), and all of them were fitted with transmitters. The number of location fixes recorded for 19 mongooses ranged from 16 to 80. Average home range size was 44.77 ± 19.04 ha (range: 5.01 - 80.51 ha). Home range overlaps could be found in male, female and inter-sexual pairs, and the degree of home range overlaps varied from 0 % to 96.4 %. Genetic analysis based on 11 microsatellites loci showed that mean number of alleles per locus was 3.27 (range: 2 – 6) and the average observed and expected heterozygosity was 0.565 ± 0.283 and 0.513 ± 0.221, respectively. Genetic diversity of population in 1997 and 2008, though not significantly different, showed trend of genetic differentiation. Genetic data also indicated no in-breeding in the Fushan population (FIS = -0.063). Mean pairwise relatedness was -0.026 (range: -0.472 to 0.338) and no significant difference was found between that of male pairs and female pairs, which suggested no sex-biased dispersal. Parent-offspring analysis suggested potential polygynous mating system. The Mantel test indicated a significantly negative relationship between relatedness of male pairs and overlaps of their home ranges, and between that of adult female pairs, which suggested that crab-eating mongooses may avoid resource competition and mating with individuals that are closely related. The crab-eating mongooses were mostly solitarily or active in either breeding or parent-offspring pairs. However, one pair of unrelated subadults which were found to move together, perhaps as a anti-predator strategy, suggested that the crab-eating mongoose may have more complex social interaction than expected of a solitary animal.
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