Movements of rehabilitated and free-ranging koalas (Phascolarctos cinereus) and their predation risk, in north-east New South Wales, Australia.

Across the study area, an array of 29 Reconyx HF2X/HP2X camera traps was established during August 2019 to August 2020. We generated a grid of 5km2 cells and fifteen cells were randomly selected; two camera traps were assigned to each cell. The spatial scale accounted for the varying size of wild dog home ranges in eastern NSW varying from 0.37–150 km2. Camera traps were deployed on tracks and trails as close to the assigned location as possible, but since I depended on access to private properties, some minor adjustment occurred (Figure 3.1). Camera traps were installed on tracks, trails, intersections or ridgelines, because wild dogs typically use those for travelling. A combination of GIS and handheld GPS were used to ensure all cameras were at least 1km apart. Camera traps were installed on posts or trees approximately 0.5 m off the ground, aiming across and along the track. The cameras were test-triggered, and resulting pictures viewed to ensure the correct placement of the detection zone. Camera traps were programmed on Rapidfire with no delay, taking 10 images per trigger. When a camera trap was active during a 24-h period (12:00:00pm to 11:59:59am) that was recorded as a single camera trap night (CTN).

在研究区域内，我们于2019年8月至2020年8月期间布设了由29台Reconyx HF2X/HP2X型红外触发相机（camera traps）组成的监测阵列。我们生成了分辨率为5平方千米的网格单元，随机选取其中15个单元，并为每个单元分配2台红外触发相机。该空间尺度的设定参考了新南威尔士州（New South Wales, NSW）东部野犬家域面积的变化范围（0.37~150平方千米）。红外触发相机被尽可能布设在靠近预设点位的步道与小径上，但因研究需获得私人领地的通行权限，部分点位进行了小幅调整（见图3.1）。相机布设于步道、小径、路口或山脊线处，因为野犬通常会沿此类路径移动。我们结合地理信息系统（GIS, Geographic Information System）与手持全球定位系统（GPS, Global Positioning System）进行点位布设，确保所有相机之间的间距不小于1千米。红外触发相机被安装在距地面约0.5米的立柱或树干上，拍摄方向横跨并平行于步道。我们对相机进行了触发测试，并查看拍摄得到的照片，以确保检测区域的布设位置准确无误。红外触发相机被设置为Rapidfire模式，无触发延迟，每次触发将拍摄10张照片。若红外触发相机在一个24小时时段（当日12:00:00至次日11:59:59）内处于工作状态，则记为1个相机陷阱夜间监测时长（camera trap night, CTN）。