African lions (Panthera leo) are critically endangered in West Africa, persisting in only 4 isolated populations. The largest population resides in the W-Arly-Pendjari (WAP) protected area complex spanning over 27,000-km2 at the borders or Burkina Faso, Benin, and Niger. This population is threatened by loss of savanna habitat to agricultural lands, disease, human persecution, and depletion of ungulate prey. Although lions are apex predators, they face increased competition due to declining prey and larger populations of competing carnivores. Spatial partitioning of habitat is often expected when niche overlap is high, but the depletion of prey in WAP may lead to increased spatial overlap and competition between lions and other carnivores. We implemented an extensive systematic remote camera survey from February-June of 2017, deploying 108 cameras within the WAP system. We used logistic regression to analyze impacts of biotic (occurrence of prey, competitor species, and humans) and abiotic (land management, location, temperature, precipitation, distances to nearest river and nearest non-protected area) variables on the presence of lions to determine the primary drivers of lion distribution. We also examined the spatial overlap between lions, their competitors, and their prey. Future analysis will include occupancy modelling to incorporate imperfect detection.
Results/Conclusions
Lions were detected at 23 of 108 camera trap stations in WAP (Burkina Faso and Niger only). The variables that best predicted lion presence were management as a national park (as opposed to hunting concession management), the distance of the camera to the nearest river, ungulate prey abundance, and competitor abundance (hyena and leopard) at the camera (p<0.01 versus a null model). All of these variables showed a positive influence on the likelihood of capturing a lion at a given camera station, which indicates spatial overlap of lions with both prey and competitor species. Human occurrence, location, temperature, precipitation, and distance to nearest non-protected area were not found to improve the model. Furthermore, camera stations at which lions were detected showed significantly more occurrences of ungulate prey (p<0.01) and competitor carnivores (p=0.015). Where we would expect to see spatial resource partitioning among species competing for prey in an unaltered ecosystem, our results indicate a significant overlap in the distribution of lions and their competitors. Here, we present critical community-level information which documents cascading ecological impacts of anthropogenic pressures in a protected ecosystem, resulting in heterogeneity of available prey and an amplified threat to endangered lions via increased potential for competition.