Rancho Grande harlequin frog (Atelopus cruciger)

Mohamed bin Zayed Species project number 10251015

THE PROBLEM Atelopus is one of the most imperilled frog genera in the Neotropic. Most species of harlequin frogs disappeared more than two decades ago and only a few still exist. Atelopus cruciger, once common in the Venezuelan Coastal Range, disappeared from its former habitats in 1986. As a result, this species is currently considered "critically endangered". The presence of a fungus in the last specimens collected suggested a fungal disease as the most likely proximal cause for their disappearance. Between 2004 and 2006, however, populations were found at three lowland locations. This evidence suggests a contraction in the altitudinal distribution of A. cruciger. Despite the urge to assess the status of populations of harlequin frogs and design management programs to assure the long-term survival of many of these species, demographic data for Atelopus species are scarce.

THE PROJECT Since 2005, we have been monitoring  one population of  A. cruciger in the northern coastal range of Venezuela to determine the abundance of frogs, the survival, recruitment, and prevalence of infection of adults at this location.

RESULTS  mark-recapture data indicate that this population tends to be stable (69-117) despite the presence of the pathogenic fungus in some of its individuals. Although prevalence of infection in this population is about 10%, preliminary results suggests that survival of infected frogs is significantly lower than that for non-infected ones. Previous reports suggested that Atelopus species are long-lived but this study indicates that life expectancy of adults is shorter but compensated by high recruitment. Under the proposed hypothesis of a short-life expectancy/high recruitment, the risk of extinction must be lower than previously thought. Nonetheless, epidemiological vigilance is recommended, given the current transmission rates of B.dendrobatidis in this population.

NEXT STEP Our next challenge is to explore how the epidemiological parameters  interact with climatic variables  in this population.