Diet composition and interspecific niche of Taohongling Sika deer (Cervus nippon kopschi) and its sympatric Reeve's muntjac (Muntiacus reevesi) and Chinese hare (Lepus sinensis) in winter (Animalia, Mammalia)

Species co-existence depends on how organisms utilize their environment and resources. Little is known about the winter diet composition and sympatric co-existence of South China sika deer and its companion species in Taohongling. In this study, high-throughput sequencing and metabarcoding trnL were used to study the diet composition and interspecific relationship including sika deer, Reeve's muntjac, and Chinese hare. Our results show that 203 genera in 90 families are contained in the diet of sika deer, 203 genera in 95 families for Reeve's muntjac, and 163 genera in 75 families for Chinese hare. Sika deer fed on Rubus chingii, Loropetalum chinense, and Eurya japonica in winter, accounting for 75.30%; Reeve's muntjac consumed mainly R. chingii, E. japonica, and Euonymus grandiflorus, accounting for 68.80%, and Chinese hare mainly fed on R. chingii, Smilax china, and Rhus chinensis, accounting for 41.98%. The Shannon index showed no significant difference between groups (p > 0.05). The NMDS analysis found considerable overlap among three species. Sika deer and Reeve's muntjac consumed similar forage plants but varied greatly in Chinese hare, which occupied the widest choice in winter, resulting in higher diet breadth and increased dietary divergence, thereby reducing competition and facilitating coexistence. The diet niche overlap index among them, as represented by Pianka's index, ranging from 0.62 between sika deer and Chinese hare to 0.83 between sika deer and Reeve's muntjac, which indicated a more similar niche and potential competition in closely related species. Our findings provide a new diet perspective of three herbivores, leading to a more comprehensive understanding of resource partitioning and species coexistence.