Potential effect of habitat disturbance on reproduction of the critically endangered harlequin frog Atelopus varius in Las Tablas, Costa Rica

D A Gómez–Hoyos,J F González–Maya,R Seisdedos–De–Vergara,R Allard,J Schipper

doi:10.32800/abc.2020.43.0001

Abstract

We studied a population of Atelopus varius in Las Tablas Protected Zone in southwest Costa Rica, where we estimated occupancy rates of tadpoles along the Cotón River. In addition, we report the first tadpoles observed in the wild in 20 years. Tadpole rate of occupancy was greater in habitat containing native forest than in disturbed areas bordering cattle pasture. This same pattern was also reflected in adult hotspots, where encounter rates were higher for adults in habitat surrounded by forest versus pasture. We present evidence for the potential effect of habitat modification on the presence and reproduction of A. varius and suspect that over time this modification impacts the species’ demography. However, further study is necessary before we can confirm that habitat change alone was the key factor involved in patterns of decline for the species.

Highlights

The variable harlequin frog Atelopus varius is categorized as Critically Endangered on the IUCN Red List of Threatened Species following a drastic population decline since the 1980s (Pounds et al, 2010)
We identified two hotspots for tadpole records using the defined segments of the Cotón River
After the dramatic population decline and local extinctions in Costa Rica and Panama in the 1980s, remnant populations such as those studied here are an important opportunity for research, especially on demography and threat impacts (Muths et al, 2011)

Summary

Introduction

The variable harlequin frog Atelopus varius is categorized as Critically Endangered on the IUCN Red List of Threatened Species following a drastic population decline since the 1980s (Pounds et al, 2010). Despite this decline, Atelopus varius is one of the few harlequin frog species remaining in Central America. Ongoing factors impacting the species include chytrid fungus, invasive species, and habitat loss and degradation (Richards–Zawacki, 2009; Pounds et al, 2010; Perez et al, 2014; González–Maya et al, 2018). Chytrid fungus is the most well–known and persistent threat affecting the species (Brem and Lips, 2008), and the Atelopus genus, while other described threats both directly and indirectly impact the species (Pounds et al, 2010)

Methods

Results

Conclusion