Spatially Explicit Capture-recapture Based Assessment for Estimation of Population and Density of an Endemic Himalayan Stream Frog (Amolops Formosus): Field Study From Churdhar Wildlife Sanctuary, India
Amolops formosus, Assam Cascade Frogs, can act as key indicators of stream health because they are a rare endemic species of the Himalayas associated with riparian habitats. For a robust density estimate, we employed the first spatially explicit capture-recapture study of an anuran species in the Western Himalayas using individual identification without physical capture. We identified 51 individuals from two sampled streams. Minimum average movement was 57.14 ± 7.14 m and 75 ± 11.18 m in the two streams, respectively. Average abundance of A. formosus was 12.73 ± 2.83 individuals based on the top N-mixture model. Water flow showed a statistically significant negative correlation with frog abundance. Density was evaluated using spatially explicit capture-recapture methods. Mean density was 5.58 ± 1.95 and 5.11 ± 1.61 individuals/ha in the two streams, respectively. Meanwhile, mean density based on linear habitat was 90.51 ± 21.68 and 87.53 ± 18.81 individuals/km. Our study demonstrated the use of spatially explicit techniques for quantifying and monitoring important sentinel species such as A. formosus using different stream parameters.ABSTRACT
ChWS showing the major streams and two sampled streams, namely CBS and KBS.
The distinct dorsal pattern in A. formosus used for individual identification.
(A) Fitted 200 m buffer mask and linear mask to the linear habitat with sampling location in CBS; (B) fitted 200 m buffer mask and linear mask to the linear habitat with sampling location in KBS.
Predicted abundance estimate with SE of A. formosus in 16 survey sites of ChWS using the top model.
(A and B) Detection probability curves for A. formosus related to distance in CBS and KBS, respectively; (C and D) A. formosus frequency of distance moved in meters in CBS and KBS, respectively; (E and F) effective sampling area as a function of increasing buffer width (m) (red line indicates buffer distance used) in CBS and KBS, respectively.
Effective sampling as a function of increasing buffer width for HN, EX, and HR. (A) HR and HN reaching a plateau fairly promptly with increasing buffer width compared with EX and HR in CBS; (B) HN reaching a plateau fairly promptly with increasing buffer width compared with EX and HR in KBS.
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