In July 2018 I participated in a tropical biology and conservation field course at the Mpala Research Station in Laikipia, Kenya. The course was run by the Tropical Biology Association (TBA) and was split into two two-week sections.the first two weeks included workshops on community conservation, river ecology, savannah vegetation, ornithology, vertebrates, reptiles, and insects. During the second two weeks, participants conducted their own research project: I studied the effect of the invasive cactus Opuntia stricta on local herbivores (ranging from dik-diks to elephants). Using dung as a surrogate for herbivore abundance, I determined the relationship between dung and cactus abundance with the aid of structural equation modelling. These models suggest the most likely causal relationship between the factors. In this case, dung abundance was indeed negatively affected by cactus abundance (once factors such as differences in visibility were accounted for). The cactus may restrict herbivore movement (reducing access to food), which may mean that herbivores avoid high-density cactus areas.