Spatial ecology of Himalayan Torrent Frog Nanorana vicina (Stolicza, 1872) in response to habitat dynamics : final report

Abstract

Spatial patterns of stream frogs have crucial implications for population dynamics and distribution that can unveil other key aspects of a species ecology. Movement and associated spatial arrangements can have effect on the fitness of both individuals and populations. Comparatively, less information is available on the ecological traits and life history for most of the streams frogs, thus creating a knowledge gap. To better understand the spatial ecology of Nanoran vicina an obligate stream frog endemic to western Himalayas, we conducted three years (2017 - 2020) study in the Himalayan streams nearby Binog wildlife sanctuary (BWLS) for an average of 63 days. We radio tagged and tracked 16 individuals of N. vicina. Our study observation suggest that the species show high philopatry and less vagility with the highest average movement ranging from 5.9 m to 5.07 m. We have also found that the individuals moved more during monsoon (4.25 m/day) than pre - monsoon (2.99 m/day) and least during post monsoon (1.06 m/day). Our results also suggested that the individuals are mostly confined to the pool section of the stream over other habitats such as cascade, run and riffle. Our study on tadpole of the same genus also revealed the preference of tadpoles in the pool. Mean overwintering tadpole density showed varying diurnal and seasonal patterns in the study pools. The nocturnal density was higher in the modified pools than natural pools during winter, while no differences were found during daytime. This pattern changed in the post winter with high nocturnal density in natural pools. We explored the seasonal resource utilization patterns of the tadpoles using habitat availability and use analyses and the present the key findings. We have also provided a checklist of herpetofaunal diversity recorded and natural history observation in the study areas. Thus, the study portrays important ecological observations on the selected species which can be followed in future to imply proper conservation measures to protect these streams from modifications.