Tiger decline caused by the reduction of large ungulate prey: evidence from a study of leopard diets in southern India

摘要

Populations of leopards and tigers in the Kalakad-Mundanthurai Tiger Reserve, India, appear to be declining. To identify the cause of this decline, we examined the diets and the relative densities of leopards and tigers, comparing scat from this park with that from the Mudumalai Wildlife Sanctuary, a park known to have high leopard and tiger densities. Results suggested that the leopard density in Mudumalai was approximately twice that in Mundanthurai. No evidence of tigers was found in Mundanthurai. Prey species found in leopard diets in the two parks was similar; albeit, mean prey weight and the proportion of large ungulates were markedly lower in the Mundanthurai leopard diet. These dietary differences are consistent with the infrequent sightings of large ungulates in Mundanthurai. Analyses of satellite data revealed that large areas of grazing land in Mundanthurai have shifted to thicket, reducing available forage for large ungulates. Since large ungulates constitute important tiger prey, the low density of ungulates in Mundanthurai might explain the apparent absence of tigers. Our findings suggest that the tiger population in the Kalakad-Mundanthurai Tiger Reserve could be enhanced via the application of habitat management for large ungulates.