Systematic camera trapping survey for terrestrial vertebrates in Xuan Lien Nature Reserve, Vietnam in 2023

Study Extent

Our survey was conducted from February 2023 to June 2023. The survey followed a systematic grid-based camera trapping design developed by Abrams et al. (2018). Due to the operation of Cua Dat hydro powerplant in the southeastern part of the reserve, and the subsequent raised water level of the Chu River since 2010, some areas of Xuan Lien has been isolated for around 15 years. Subsequently, our survey only covered about 77% of the reserve. However, the core zone of the reserve was fully covered by our survey.

Sampling

The survey followed a systematic grid-based camera trapping design developed by Abrams et al. (2018). In total, we deployed 70 camera traps at 35 locations, which were spaced at about 2.5 km apart with a maximum acceptable deviation of 10% (approximately 250 m). Hence, the minimum distance between any camera stations was 2.0 km. However, at one station, both cameras were lost, and therefore we were only able to retrieve 68 cameras at 34 stations. Each camera trap station consisted of two non-facing camera trap devices (Reconyx Hyperfire) that were set within a 20 x 20 m plot. Cameras were placed on tree trunks 20-40 cm above the ground and were set up to take three burst photos per trigger without delay, recording the date and time of each photo. All cameras were set at high sensitivity level, and were working continuously during the survey.

Method steps

1. Collected data were copied into folders named by camera and station codes. Each photo was then identified and moved to a corresponding species sub-folder. The completely identified camera dataset was then checked and analyzed using camtrapR package in R to generate basic statistic report for the collected data. Detections from the two camera devices in the same station and within a 60-minute threshold are considered as a single independent detection. The dataset is then structured as an occurrence dataset, formatted according to the recommendations of the Darwin Core Archive. In this dataset, each row corresponds to an independent detection.

1. Aves
   common name: Birds rank: class
2. Mammalia
   common name: Mammals rank: class
3. Reptilia
   common name: Reptiles rank: class

Xuan Lien Nature Reserve, Thanh Hoa, Vietnam