Effects of anti-poaching patrols on the distribution of large mammals in Taï National Park, Côte d'Ivoire (advance online)

The effectiveness of protected area management is a major concern. In Tai National Park, Cote d'Ivoire, recurrent human pressure challenges the ability of law enforcement authorities to protect wildlife. During 2010-2015 we studied the implementation of law enforcement in the Park to determine (1) the potential for improvement of the protection of large mammals and (2) the minimum patrolling effort needed to obtain increases in their populations. We recorded presence of large mammals and illegal activities in two areas within the Park, the research area (210 km(2)) and the rest of the Park (5,150 km(2)), and compiled data about patrolling efforts from the Park authorities. Using a generalized linear mixed model we identified a relationship between increased patrolling effort and the relative abundance of large mammals, especially for monkey groups, pygmy hippopotamuses Choeropsis liberiensis and duikers. At low patrolling efforts duiker encounter rates remained stable, whereas rates of encounter with monkey groups and pygmy hippopotamuses decreased. Chimpanzee Pan troglodytes verus encounter rates were slower to respond and remained stable at higher patrolling effort, but decreased at low patrolling effort. Our findings suggest that a minimum of 1.32 patrol days per km(2) over 2 years is required for chimpanzee and monkey populations to increase, whereas a patrolling effort of 0.48 days per km(2) over 2 years would lead to an increase in duiker and pygmy hippopotamus populations. We maintain that the patrolling effort required to ensure an increase in wildlife can be estimated relatively precisely from multi-year biomonitoring programmes.