Population structure of critically endangered Western Derby eland in the Niokolo Koba National Park, Senegal

Bc. Kristýna Stehlíková

Master's thesis

Abstract:

Western Derby eland is a critically endangered subspecies whose last refuge appears to be the Niokolo Koba National Park in Senegal. Despite its critical status and very limited area of distribution, there have not been many studies done considering their population and demographic parameters. This study brings the assessment of Western Derby eland’s current population status by analysing the structure and size of the population and its demographic parameters from images collected by camera traps during the dry season in 2021. The population size was analysed using the secr package in R Studio, resulting in an estimated density of 0.1 females/km2 (± 0.05) and 0.04 males/km2 (± 0.01). From that, the abundance was estimated at 126 females (CI95 from 76 to 466) and 50 males (CI 95 from 20 and 151). Together with the estimated number of calves this then resulted in the total population size of approximately 255 individuals. More detailed analysis of the population showed adult males and two years old individuals as the most vulnerable, possibly affected by combination of several factors between which potentially belongs poaching, higher predation pressure or livestock encroachment and other agricultural activities in the park. The population also seemed to be centralised only into one, relatively small area in the park, which may indicate either limited possibilities for dispersion or lack of data about its distribution. It is not clear from the results weather there is an increasing population trend or not and what specific factors have the biggest influence on the population size. In the future, it will be necessary to continue with a monitoring specifically targeted on the elands, to address those factors and bring solutions to the park managers, which would help them to better understand this subspecies and streamline its protection.

Keywords

population size, population structure, Western Derby eland, Niokolo Koba National Park, demographic parameters, spatially explicit capture-recapture model

Language used: English

Date on which the thesis was submitted / produced: 23. 4. 2023

Thesis defence

• Date of defence: 31. 5. 2023
• Supervisor: doc. Ing. Karolína Brandlová, Ph.D.
• Reader: Marine Drouilly, Mgr., externi

Czech University of Life Sciences Prague

Faculty of Tropical AgriSciences

Master programme / specializace:
Wildlife and Livestock Production, Management and Conservation / Wildlife Management and Conservation