Indicative response of Oxysternon festivum Linné (Coleoptera: Scarabaidae) to vegetation condition in the basin of the Orinoco river, Venezuela

A good indicator species should be easy to sample, identify and measure, and be informative about its ecological context. We analysed data from a nation-wide dung beetle survey in Venezuela in order to assess the indicative response of Oxysternon festivum (Coleoptera: Scarabaeinae) to vegetation and climatic condition in the Orinoco river basin. Our approach consisted of two steps: estimating habitat suitability (HS) from historical records and mean environmental conditions, and analysing four different properties measured during a nationwide survey (occurrence, total abundance, individual body size, and total biomass), in relationship with HS and current environmental covariates measured from remote sensors. O. festivum population status could not be completely explained by historical or current conditions alone, but rather by combinations of both. It was strongly associated with forest vegetation, but abundance, biomass and body size increased under harsher (hotter and drier) climatic conditions. Thus, O. festivum seems to be sensitive to changes in vegetation cover, but tolerant to certain levels of perturbance, where it probably replaces other, more sensitive species. Fully understanding the role of O. festivum requires the analysis of its relationships to other species. We strongly recommend the development of similar protocols for the analysis of other potential ecological indicator species, drawing information from historical and contemporary sources and exploiting the available statistical tools to reveal complex patterns. Given the high diversity of dung beetles, and the growing interest in this group, several candidates will probably be found in most tropical countries. © 2016, Springer International Publishing Switzerland.