Spatially restricted occurrence and low abundance as key tools for conservation of critically endangered large antelope in West African savannah

The effective conservation of mammals on the brink of extinction requires an integrated socio-ecological approach, yet the updated ecological knowledge of species remains fundamental. This study brings spatiotemporal behaviour, population structure, age-specific survival rates, and population size estimate of the Western Derby eland (WDE) in the Niokolo Koba National Park (NKNP), Senegal, investigated during dry seasons 2017 and 2018. WDE was strongly localised in the core area of NKNP (< 5%), active throughout the day with the highest peak in the hottest daytime, with a mean group size 7.6 ± SE 8.9. The adult sex ratio was female-biased and showed low annual adult male survival rates. The population consisted of high proportion of juveniles, whilst adults did not exceed 40%. The estimated population density was 0.138 WDE/km2 (± 0.0102) and estimated size 195 WDE in NKNP (CI95 from 54 to 708 individuals). Findings highlighted that the WDE population has potential to expand in the NKNP, due to an underutilized capacity. The age-specific vital rates indicate adult males as the most vulnerable; suggesting either an increase in the large predators’ population, livestock encroachment pressure, and/or poaching. Findings imply that targeted monitoring with science-based interpretation may bring forward strong conservation solutions to the protected area management decision-makers.