Ecological aspects of the endemic tree frog Ololygon kautskyi (Anura: Hylidae) in an Atlantic Forest area of Southeastern Brazil

Abstract

ABSTRACT We studied several ecological aspects of the endemic Ololygon kautskyi in the Reserva Biológica Duas Bocas (RBDB), Espírito Santo, Brazil, including activity, detectability and use of microhabitats. Fieldwork was carried out from February 2018 to March 2019, between 8:00 and 23:00, in 22 transects of 50 m along streams. For each individual frog found, we recorded the hour, the microhabitat in which it was detected, the height above ground, snout-vent length (in mm), and mass (in g). We measured the air temperature (°C), relative humidity (%), stream water temperature (°C), pH, and conductivity. We tested for differences in body size among sexes and estimated the detectability of the species in relation to the environmental variables. We recorded a total of 93 individuals from O. kautskyi, with the majority of individuals recorded between 18:00 and 22:00. Females were significantly larger in body size than males. The detection probability of the species was affected by the period of the day, air temperature and relative air humidity. Ololygon kautskyi used five different types of microhabitats, and vegetation was the most used microhabitat by the species. We conclude that O. kautskyi is nocturnal, mainly uses vegetation on stream banks, is more likely to be detected during cold and dry days, and is dimorphic in body size with females being larger than males. There is currently insufficient information to assess the conservation status of O. kautskyi. However, considering that the species is endemic to a relatively small portion of the Atlantic Forest biome in the state of Espírito Santo and that its ecology is strongly associated with riparian zones, we believe that the species would be eligible to be categorised in some threat category.