The Nagarhole ecosystem supports the highest density of herbivores anywhere in Asia. Studies carried out in Nagarhole show that the estimated mean number of large herbivores in Nagarhole is 108 animals per sq km. Large herbivores are defined as ungulates and primates weighing more than 5kg and in Nagarhole these comprise of – Muntjak, Chital, Sambar, Four-horned antelope, Gaur, Wild pig, Asian Elephant, Common Langur and the Bonnet Macaque. This translates into a biomass of 14746 kgs per sq km. This is comparable to the
Masai Mara in Africa, which has a biomass of 19200 kgs.
Of these herbivores, the Chital, Sambar, Gaur, Wild pig, Muntjak and Common Langur are preyed upon by the Tiger, Leopard and Wild Dog. These herbivores are classified as principle prey species and occur at a estimated mean density of 91 animals per sq km. The prey species can be further divided on the basis of body weight into small (Langur, young
Chital and young pig ), medium (yearling and adult Chital, adult pig, yearling and young Sambar and young Gaur), and large (adult Sambar and adult Gaur) and studies show that Tigers preferentially selected large prey, Leopard medium and small prey and the Wild dog medium prey. Because the availability of prey in the appropriate size class is not a limiting resource in Nagarhole, selective predation has facilitated large carnivore co-existence in the park.
The principal reasons for large carnivore coexistence in Nagarhole as opposed to the African savanna are ecological factors such as adequate availability of appropriate sized prey, dense cover and tree density which is absent in the African savanna and the fact that behavioral factors such as habitat specificity, choice of hunting sites or inter-specific dominance play a relatively minor role in Nagarhole.