A decade under lens: Characterizing wildlife mortality from disease and infection in Chitwan National Park, Nepal

Abstract

Mortality and health issues are becoming an emerging issue in the conservation and management of wildlife populations. Understanding the causes of mortality is necessary for proper management of wildlife and habitats. To address this, a mixed approach was employed: we conducted a longitudinal analysis of a decade (2010–2019) of observed mortality count data from Chitwan National Park, Nepal. These data are subject to inherent surveillance biases, and our results represent detected mortality patterns. Additionally, a focus group discussion was conducted to gain a deeper understanding of the causes and trends of mortality and conservation efforts. There was a total of 525 recorded cases, of which mortality causes were determined for 82%; for the remaining 18%, causes were unidentified. Herbivore mammals accounted for the highest mortality (61%), followed by carnivores (16%). Of determined mortality causes, anthropogenic causes were the leading contributors to mortality (33.14%), followed by natural causes (23.62%) and diseases and infections (13.33%). Generalized linear models (negative binomial/poisson) revealed a significant 15.3% annual increase in overall wildlife mortality counts, driven by significant increases in disease and infection by 25.8% per year and conflict/competition by 17.4% per year. Rhinoceros was the species suffering the highest mortality count (34%), which increased by 42.9% per year, followed by elephants, gharial, deer, and tigers. The health assessment revealed that wound and bacterial infections, tuberculosis, and parasitic diseases were the primary factors responsible for mortality. Furthermore, the research indicates a concerning increase in mortality counts due to disease and infections and highlights an urgency for the development of comprehensive conservation efforts, public awareness, and disease control strategies. Routine immunization for livestock and development of species-specific plans for disease diagnosis and treatment in well-equipped wildlife care hospitals are crucial. Additionally, regular research on wildlife health monitoring and research-based effective conservation should be prioritized.