Small ponds support high terrestrial bird species richness in a Mediterranean semiarid region

Abstract

Ponds are among the world’s most endangered freshwater ecosystems. A comprehensive knowledge of pond biodiversity is urgently required to inform effective pond management and conservation actions. Most studies about pond biodiversity focus on aquatic taxa, while the terrestrial biodiversity, especially of birds, has been little studied. Moreover, the few studies existing on pond biodiversity do not account for different detection rates of species, thus yielding biased results. Here, we apply a hierarchical Bayesian modelling technique to data obtained from visual censuses to estimate bird species richness associated with small ponds in a semiarid region, considering the imperfect detection of species. The model incorporates specific responses to site characteristics (pond typology), landscape (environmental heterogeneity) and at regional scale (mean annual precipitation). The studied ponds were used by two thirds of the terrestrial breeding bird community of the study region. Our modelling approach increased by an average of 7.5 species the observed site-specific richness. Drinking troughs supported a greater richness than other pond types. Environmental heterogeneity was positively related with species richness, whereas no clear relation was observed between richness and precipitation. In addition to ecosystem services provided by ponds to human welfare, our results suggest these small isolated habitats may act as key landscape elements for terrestrial birds in semiarid regions.