Competition versus opportunism: Diet and trophic niche relationship of two sympatric apex carnivores in a tropical forest

Abstract There is a little understanding of how apex carnivores partition their diet to coexist. We studied food habit and trophic niche overlap of two apex carnivores, tiger and leopard in the tropical forest of Similipal tiger reserve, eastern India. We used line transect and scat analysis method, to estimate the prey availability and determine the diet and prey selection of two apex carnivores. Tigers consumed mostly large and medium-sized prey, whereas leopards mostly consumed medium and small-sized prey. Both carnivores were not random in their consumption of prey, sambar and wild pigs were selectively consumed by tigers, whereas leopards selectively consumed wild pigs, barking deer and mouse deer. Dietary overlap between two carnivore species was moderate (Pianka's niche overlap index: 0.55), and trophic niche breadth (Levin's standardized niche breadth) of the leopard (0.52) was greater than that of the tiger (0.37). Overall, tigers exhibited specialized feeding habits, whereas leopards showed generalist feeding habits. Our study highlights the opportunistic nature of leopards and probably a reason for the species successfully coexist with tigers.