Using mobile smartphones and bioacoustics to monitor endangered bird species

Abstract

Monitoring the status of endangered wildlife is a critical foundation for biodiversity conservation efforts. The use of autonomous acoustic recorders to monitor wildlife has become increasingly popular in terrestrial tropical systems. However, these recorders are expensive and not available for purchase and repair in all countries. The development of easy‐to‐use and low‐cost devices is therefore needed for applications worldwide. In this study, we modified and installed smartphone devices to operate and record sounds produced by the Vietnamese Crested Argus Rheinardia ocellata in Kon Chu Rang Nature Reserve, Vietnam, in 2021. We used the software package RAVEN to create spectrograms and to identify Crested Argus calls from acoustic recordings and used the program MARK to estimate occupancy and detection probabilities. We recorded calls of Crested Argus at 16 of 40 locations and most calls were recorded in the northern and eastern parts of the nature reserve. Our model‐averaged estimates of detection probabilities indicated that detection in the morning or afternoon was c. 0.50 and constant over seven sampling days. Our overall average occurrence probability of Crested Argus was 0.43 (standard error = ±0.08), but we found occupancy to be positively correlated with distance to the nearest village, indicating that poaching may negatively affect this species. Based on these data we suggest that the Kon Chu Rang Nature Reserve and possibly two adjacent nature reserves, namely An Toan Nature Reserve and Ba To Proposed Nature Reserve, might be important sites for Crested Argus.