How can spatio-temporal overlap in mammals assist in maximizing biodiversity conservation? A case study of Periyar Tiger Reserve

Abstract

While global mammalian diversity is collapsing due to increased poaching and habitat loss, evidence-based conservation in protected areas is often regarded as a panacea. Tiger reserves in India set an example, where annual camera trap monitoring is conducted for understanding the trends in the tiger population. However, less is known about other co-predators and their prey species that occur in the same area. The fundamental hindrance being the absence of individual pelage pattern within these species (i.e. unique pattern on the body), as well as the absence of species-specific monitoring. As a result, there is a demand in techniques that can avail maximum biodiversity information from the existing monitoring protocols. Here, we conducted camera trapping in Periyar Tiger Reserve to evaluate spatiotemporal overlaps within different carnivores, and between prey-predators. Camera trapping was conducted at high resolution (2 km2) for 30 days at 253 locations that yielded 6092 photographs of 18 mammals. Their temporal overlap was estimated using ‘overlap’ R package, while the spatial association was estimated using ‘co-occur’ package. Three large-ranging top predators (tiger, leopard and dhole) were found to have activity peaks segregated temporally. Relationship of these predators with their prey species highlighted the role of body sizes, where largest predator (tiger) had higher overlap with large-bodied prey (gaur and sambar), while small-bodied predator (leopard and dhole) overlapped small-bodied prey (barking deer and wild pig). Results highlight the importance of large-sized prey in conserving the tiger densities of this region. However, selectively conserving only large-bodied prey can have repercussions on other sympatric carnivores, who require different body-sized prey species. Our results have implications for all protected areas in the tropical developing countries, which are mostly smaller in area with species-centered conservation agenda. We highlight the importance of considering species-specific carrying capacity of all co-predators in the region, to optimally conserve the prey-base through habitat restoration, so as to maximize biodiversity conservation within a limited area.