Global Ecology and Conservation (Dec 2024)
Recovery of tigers (Panthera tigris): Assessing ecological carrying capacity in Bardia-Banke Complex, Nepal
Abstract
Tigers (Panthera tigris) are endangered wild felids, despite ongoing efforts to recover populations globally. The majority of the global population is concentrated within ∼ 40 “source sites”. Protection and effective management of these populations constitute the cornerstone of global tiger conservation strategies. Reliable population estimates and site specific carrying capacities are important for informed management actions. Here, we estimated the ecological carrying capacity of tigers based on prey densities in the Bardia– Banke Complex in western Nepal embedded within the Terai Arc Landscape, a globally significant tiger conservation landscape. A total of 303.8 km line transects (n=195) were surveyed in the Bardia–Banke Complex. We estimated an overall density of 69.09 (95 % CI=52.32 – 91.23) ungulates/km2 and biomass of 2736.92 (1807.83 – 4830.12) kg/km2 in Bardia National Park (NP), and 25.67 (18.22 – 36.18) ungulates/km2 and biomass of 1356.65 (646.85 – 2994.86) kg/km2 in Banke NP. The available prey base can support 133 (101 – 177) adult tigers in Bardia NP and 28 (20 – 40) in Banke NP. We also carried out systematic camera trap survey across the Complex with a sampling effort of 13,365 trap days (719 camera sites). In core habitats of Bardia and Banke NP, we estimated tiger abundance of 77 (72 – 83) and 12 (9 – 15) at a density of 7.96 and 2.18 tigers per 100 km2 respectively. Our study shows the tiger populations in the national parks are below carrying capacity. We emphasize the need for robust estimates of prey abundance and carrying capacity of tigers in a given landscape for effective conservation planning. We highlight the importance of high prey density and biomass with effective human-tiger conflict mitigation measures to sustain a large tiger source population.
