Negligible Impact of Siam Weed (Chromolaena odorata) on the Distribution and Activities of Olive Baboons (Papio anubis) in Gashaka-Gumti National Park, Nigeria

On a global scale, the spread of alien invasive species is one of the leading causes of reduction in native species populations and, sometimes extinctions. Still, only a few studies in Africa have demonstrated the effect of alien invasive species on animal communities. In this study, we investigated the effect of the Siam weed (Chromolaena odorata) on the distribution and activity of a ubiquitous primate species, the olive baboon (Papio anubis), in Gashaka-Gumti National Park. We predicted that baboons would be mostly observed in areas that are not heavily invaded by the Siam weed and that the frequency of baboon activities would be higher in those areas. Using direct observations in radial line transects, a generalised linear mixed effect model, and chi-square tests, we found that Siam weed had no impact on the occurrence and activities of baboons in the national park. Interestingly, we observed that baboons frequently travelled in or around C. odorata bushes. However, we did not compare the percentage of time spent travelling with the time spent on other activities. Our study demonstrates that normal activities of ubiquitous primates are unlikely to be affected by the spread of the highly invasive Siam weed in an Afrotropical forest.