Abstract

As an example of the niche overlap theories this paper reports grouping pattern, habitat use and overlap by four sympatric ungulate species, Chital (Axis axis), Sambar (Rusa unicolor), Nilgai (Boselaphus tragocamelus) and Goral (Naemorhedus goral) in Pathri Rao Watershed within Shivalik Ecosystem, India. A length of 384 km of trail walk and 125 permanent circular plots of 10 m radius were used to collect data on group size, age, sex composition and various ecological and topographical factors governing presence/absence of species within the study area. Chital had the highest mean group size (7.74±1.19), followed by Nilgai (5.40±0.88), Goral (2.50±0.54) and Sambar (1.56±0.18). Group size of Chital varied significantly across seasons in comparison to the other sympatric ungulates. Chital used all the available habitat types with significant differential use (F=3.35, p<0.04). Goral and Sambar only used three habitat types with significant differences (Goral F=4.49, p<0.001; Sambar F=10.17, p<0.001). Nilgai used preferentially flat areas. Discriminant functions exceeded the classification accuracy expected by chance at a significant level of 0.01 (Press’s Q=131.90>6.63) with overall 52.3% of cases classified correctly. This analysis indicated clear segregation of the four species along the three discriminant functions with total isolation between Nilgai and Goral along the first axis. Niche overlap analysis predicted segregation of habitat use by sympatric species along one or other niche axis which governs continued existence of the sympatric species in the study area. Locations of artificial water holes determine grouping pattern, habitat use and habitat segregation, as expected by other ecological correlates in the study area.