Señaris, C., M. Lampo, A. Rodríguez-Contreras & G. Velásquez

Breeding site fidelity of the critically endangered toad Atelopus cruciger (Anura: Bufonidae): implications for its conservation. pp. 217-228 plus Supplementary document S1 and Supplementary document S2.

Abstract. Harlequin Toads (Bufonidae: Atelopus) are among the most diverse Neotropical amphibians, but 84% of the known species are threatened with extinction mainly due to the fungal disease chytridiomycosis. With no effective tools to mitigate chytridiomycosis in the wild being available, captive breeding is currently the only option to ensure the long-term survival of many Harlequin Toad species. However, the life history and ecology of most species is still largely unknown. Using spatially explicit capture–recapture data from 2005–2013, we studied breeding habitat use and reproductive phenology of the critically endangered Rancho Grande Harlequin Toad, Atelopus cruciger. This species is a seasonal breeder that reproduces exclusively during the dry season. Adult males and females, but also juveniles, migrate from the forest to the river at the beginning of the dry season and return to the forest as soon as the rainy season begins, although a few adult males may remain on the riverbank throughout the year. Despite these seasonal displacements, the toads return to the same locations on the riverbank every year. Both female and male adult toads exhibit a strong breeding site fidelity, occupying small areas (≤ 5 m²) along the river margins. Adults were mainly active on rocky substrate and vegetation during the day, with males occupying significantly more elevated spots closer to the stream than females. Male territories tend to overlap, but we observed no aggressive or territorial defence behaviour. We discuss the implications of habitat use and high site fidelity for in situ and ex situ conservation measures of this critically endangered toad.

Key words. Amphibia, Harlequin Toads, reproductive phenology, seasonal migration, habitat use, home range, captive breeding, Venezuela.