Passive acoustic monitoring is rapidly gaining recognition as a practical, affordable and robust tool for measuring gun hunting levels within protected areas, and consequently for its potential to evaluate anti-poaching patrols’ effectiveness based on outcome (i.e., change in hunting pressure) rather than effort (e.g., kilometres patrolled) or output (e.g., arrests). However, there has been no report to date of a protected area successfully using an acoustic grid to explore baseline levels of gun hunting activity, adapting its patrols in response to the evidence extracted from the acoustic data and then evaluating the effectiveness of the new patrol strategy. We report here such a case in Cameroon’s Korup National Park, where anti-poaching patrol effort was markedly increased in the 2015–2016 Christmas/New Year holiday season to curb the annual peak in gunshots recorded by a 12-sensor acoustic grid in the same period during the previous 2 years. Despite a three- to five-fold increase in patrol days, distance and area covered, the desired outcome – lower gun hunting activity – was not achieved under the new patrol scheme. The findings emphasize the need for adaptive wildlife law enforcement and how passive acoustic monitoring can help attain this goal, and they warn about the risks of using effort-based metrics of anti-poaching strategies as a surrogate for desired outcomes. We propose ways of increasing protected areas’ capacity to adopt acoustic grids as a law enforcement monitoring tool.

Where one or a few tree species reach local high abundance, different ecological factors may variously facilitate or hinder their regeneration. Plant pathogens are thought to be one of those possible agents which drive intraspecific density-dependent mortality of tree seedlings in tropical forests. Experimental evidence for this is scarce, however. In an African rain forest at Korup, we manipulated the density of recently established seedlings (~5–8 wk old; low vs. high-density) of two dominant species of contrasting recruitment potential, and altered their exposure to pathogens using a broad-spectrum fungicide. Seedling mortality of the abundantly recruiting subcanopy tree Oubanguia alata was strongly density-dependent after 7 mo, yet fungicide-treated seedlings had slightly higher mortality than controls. By contrast, seedling mortality of the poorly recruiting large canopy-emergent tree Microberlinia bisulcata was unaffected by density or fungicide. Ectomycorrhizal colonization of M. bisulcata was not affected by density or fungicide either. For O. alata, adverse effects of fungicide on its vesicular arbuscular mycorrhizas may have offset any possible benefit of pathogen removal. We tentatively conclude that fungal pathogens are not a likely major cause of density dependence in O. alata, or of early post-establishment mortality in M. bisulcata. They do not explain the latter's currently very low recruitment rate at Korup.

The diurnal primate community of the Korup area of south-west Cameroon is rich in species and high in endemism. Two years monitoring in the Support Zone around Korup National Park have shown that, although all species of the original community are still present, Preuss' red colobus and drill, which were considered to be threatened in the early 1990s, have declined further and are probably facing local extinction. Densities of the crowned monkey also seem to have declined. Only mona and putty-nosed monkeys have an expanded distribution, and densities that are within the range of those reported from previous studies in the region. Although hunting is the most important cause of these declines, logging also appears to be having a detrimental effect. In logged forest group densities of chimpanzee, red-capped mangabey, mona monkey and red-eared monkey decreased between the two survey years, whilst remaining constant or increasing in unlogged forest. The frequency of associations of guenon species did not differ between logged and unlogged study sites, but encounters of associations of all four guenon species were only found in unlogged forest. We strongly recommend enforcement of anti-poaching activities inside the Korup National Park, and establishment of wildlife management in the Support Zone, as only a combined strategy can successfully guarantee the persistence of the wildlife of the region.