Montes de María is the best-preserved tropical dry forest fragment in the Colombian Caribbean, making it an ideal location for studying the impacts of human disturbance on local ecosystems. This study analyzed the ecological structure of diurnal butterflies in both forested and disturbed areas using 16 circular plots to identify relationships between alpha and beta diversity, and the geographic distance between disturbed areas and native forests, using a range of metrics, including range-abundance and rarefaction curves, nonlinear models, and the Bray–Curtis dissimilarity index. Results revealed three distinct species assemblages associated with forest, intermediate disturbed areas (IDA), and disturbed areas (DA). Nonlinear models show that IDA are more diverse than forest and DA. However, forests have more beta diversity among plots than IDA and DA. Indicator species for each butterfly assemblage were also identified. Thus, although new butterfly species assemblages emerge from a new human land-scape, it is clear that species that only occur within dry forest fragments are lost when forest fragments disappear. Overall, these findings have important implications for conservation efforts and understanding how human disturbance affects biodiversity in tropical ecosystems.