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

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.

EL SAPO ARLEQUÍN DEL CHOCÓ (Atelopus spurrelli Boulenger, 1914) EN EL PARQUE NACIONAL NATURAL UTRÍA, COLOMBIA: DENSIDAD POBLACIONAL Y RECOMENDACIONES PARA SU MONITOREO Y CONSERVACIÓN

“…Algunas especies como Atelopus cruciger, A. ignescens, A. varius y A. zeteki cuentan con estudios poblacionales robustos (Ron et al, 2003;Lampo et al, 2012;2017;McCaffery et al, 2015;González-Maya et al, 2018, Gómez-Hoyos et al, 2020 que han permitido estimar parámetros demográficos y evaluar tendencias poblacionales, así como identificar amenazas y su efecto sobre las poblaciones. Sin embargo, la mayoría de sapos arlequín no cuentan con estudios poblacionales de línea base y para unas pocas especies como A. elegans y A. spurrelli solo se cuenta con evaluaciones poblacionales rápidas (Gómez-Hoyos et al, 2014;Gómez-Hoyos et al, 2017) y no es posible conocer su tendencia.…”

A review of chemical defense in harlequin toads (Bufonidae: Atelopus)

“…Atelopus have suffered a particularly drastic decline; a major survey in 2005 found that, of species with sufficient population trend data (52 of 113 known species), 81% were in decline and 56% were possibly extinct. Chytridiomycosis, a disease caused by the fungal pathogen Batrachochytrium dendrobatidis, is implicated in many of the declines ( La Marca et al, 2005 ; Lampo et al, 2017 ), and habitat loss and degradation are likely also important drivers ( Gómez-Hoyos et al, 2020 ; Jorge et al, 2020b ; Santa-Cruz et al, 2017 ) . Recently, several Atelopus species thought to be extinct or locally extirpated have been rediscovered ( Barrio Amorós et al, 2020 ; Enciso-Calle et al, 2017 ; Escobedo-Galván et al, 2013 ; Tapia et al, 2017 ); however, these rediscovered populations are still at risk of extinction due to habitat loss, invasive species, low genetic diversity, and chytridiomycosis ( Byrne et al, 2020 ; González-Maya et al, 2018 ; Kardos et al, 2021 ).…”