Global congruence between cuckoo species richness and biodiversity hotspots

Abstract

Considering loss of biodiversity a global threat, cost-effective tools for monitoring spatial distribution of species are relevant for conservation planning. The aims of this study were (a) to compare the global pattern of species richness in Cuculidae with species richness of birds, amphibians and mammals; (b) whether it is spatially congruent with hotspot areas of biodiversity at a global scale; and (c) whether the distribution of night light intensity reflecting human population density is associated with cuckoo species richness. We mapped the global distribution of all cuckoo species, classified as parasitic or non-parasitic species. Species richness was calculated at a fixed spatial scale for: Cuculidae, amphibians, birds and mammals. We applied Generalized Linear Mixed Models in order to explore the associations between species richness of each group of animals, night light intensity and hotspots of biodiversity areas at a global scale.Worldwide patterns of species richness of parasitic and non-parasitic cuckoos reflected species richness of birds, amphibians and mammals. In addition, and importantly, species richness of cuckoos was spatially congruent with hotspot areas of biodiversity across the world. Finally, night light intensity was slightly positively associated with species richness of parasitic cuckoos. Our findings confirmed that cuckoos constitute an important surrogate of high species richness of different animal taxa at a global scale: It is easy to learn how to identify cuckoos, whereas other species of birds, mammals or amphibians can only be identified by specialists. Our findings also suggest that other parasitic cuckoo species can be used as a biodiversity surrogate in a similar way as the common cuckoo in Eurasia.