Abstract
The competitive relationship and coexistence pattern among close related species have long been one of the hot issues in ecological research. Interspecies interactions can exert important influences on the local distribution of rare species. Black muntjac Muntiacus crinifrons is an endemic species to eastern China, currently restricted to limited regions. In contrast, Chinese muntjac Muntiacus reevesi is the most common and widespread deer in southern China. Both species co-occur in southern Anhui and western Zhejiang Province. Little is known about the interaction of these two sympatric-related species. In this study, to investigate the site use determinants and co-occurrence pattern of the two sympatric muntjac species, we conducted a camera trap survey across about 250 km(2) in mountainous area of southern Anhui Province, China. We adopted a multistep approach to incorporate habitat preferences while modeling occupancy and detection. We found that the two species did not separate along elevation gradient (range from 400 m to 1,400 m) as described in previous studies. Results of single-species occupancy models indicated that elevation had positive effects on the site use of both species, while slope had an opposite influence on their site use. Positive effects of elevation on the site use implied that both species try to avoid human interference at low elevations. Significant negative effect of slope on the site use of black muntjac suggested that the species prefer habitat with gentle slope and avoided steep. Co-occurrence models and species interaction factors provided evidence that the two muntjac species had an independent occupancy (ψ (BM CM) = ψ (BM cm), SIF = 1) and exhibited a positive species interaction in detection probability (p (BM) < r (BM CM)). Combined with the results of previous studies, we suggested that it was fine differentiation in microhabitats and food resources utilization rather spatial or temporal segregation that allowed the two species co-occurrence. The site use determinants revealed in our study would be useful for the habitat conservation and restoration for the rare black muntjac, and the co-occurrence pattern of the two sympatric muntjac species could provide useful information for deep understanding of the coexistence mechanism among forest-dwelling ungulates.