In the search of good biodiversity surrogates: are raptors poor indicators in the Baja California Peninsula desert?

Abstract Predators have been considered to be good surrogates for measuring biodiversity, and raptors, in particular, have been proposed and used as biodiversity surrogates. This assumption is based on the general idea of concordance between two taxonomic groups that showed a similar spatial/temporal structure, with the aim of using one of the groups as a surrogate of the other. If a surrogate can be identified, then inferences can be made and conservation strategies can be established about the other. Assemblage concordance measures the degree of relationship between the composition patterns shown by two groups of organisms. In this study, we evaluated the effect of spatial and environmental variability on the degree of assemblage concordance between top‐order predators (i.e. raptors), as the surrogate group, and vascular plants, reptiles, birds and mammals, as target groups. We also examined the potential causes of assemblage concordance and the degree to which the surrogate assemblage can predict community structure in the desert of southern Baja California Peninsula. Levels of assemblage concordance varied in all cross‐taxon comparisons. We found that the concordance between raptors and birds may be due a combination of their similar responses to environmental gradients and trophic interactions, whereas other patterns of assemblage concordance are more likely derived from interactions between groups. We found low predictability and that no particular taxonomic group significantly predicted all the other groups. The low and shifting levels of assemblage concordance, in terms of environmental and spatial variables, suggest that raptors are poor biodiversity surrogates in this desert ecosystem.