Reproductive activity, microhabitat use, and calling sites of Pristimantis bacchus (Anura: Craugastoridae)

Abstract

Pristimantis bacchus is an endangered terrestrial frog, endemic to cloud forests of the northern part of the Cordillera Oriental in the Colombian Andes. The knowledge of its reproductive biology and microhabitat use can offer important information for future conservation programs. We evaluated the reproductive activity and microhabitat use for both sexes, and selection of calling sites by males during rainy and dry seasons. Individuals of all reproductive conditions were observed throughout the sampled months; however, we observed a higher abundance of frogs during the first rainy season, after the driest months of the year. Thus, this population seems to have continuous reproductive activity, with an apparent peak at the onset of the first rainy season of the year. There were differences in the microhabitat use between sexes, between adults and juveniles, and between non-reproductive and reproductive females. Males use a wider variety of substrates at higher perches, while females were mainly found on leaf litter and over leaves at low heights; however, ovigerous females mostly occupied substrates above 120 cm. Juveniles were less abundant than adults, and occupy low substrates, mostly at forest litter. Two selection models evaluated the preference for calling sites, related to physiological requirements of humidity and for vocal sound dispersion. Males preferred to vocalize on perches at heights among 41-120 cm and with a vegetal structure that maintains high humidity, avoiding desiccation, and reducing exposure to predators. Therefore, intrapopulation variation in microhabitat use in this species is related to age, sex, reproductive condition, and physiological requirements.