Camera trapping videos and photos, including pre-processing
Initially the whole area was divided into a grid system of size 4×4 km2 (Figure 1) and between two and five camera-trap locations in each grid cell were selected based on the presence of carnivore sign and prey trails. Two infrared cameras (Eastern Red Hawk E1B 6210M and LTL6210MM, Manufactured by Shenzhen Weikexin Science and Technology Development Co. LTD Shenzhen, China) were set facing each other at each trap station to increase capture probabilities and capture the fur patterns on both sides of leopards, of which one was set to record short videos (10 second length) and one to record photos (3 photos per trigger event). In order to capture quality images, cameras were attached to trees 45–50 cm above the ground at a distance of 3.5–4 m from animal trails, and all vegetation or other obstacles in front of the cameras were removed (Qi et al., 2015). All photographs were automatically stamped with the time and date, moon phase and respective location ID. A total of 102 camera locations operated between March 2017 – June 2019, and among them, 78 cameras successfully functioned to collect data over three sampling stages in two different seasons (see below for details) with 131 (March–July 2017), 120 (September–December 2018), and 134 (March–June 2019) consecutive days being sampled. Each camera was visited approximately every two months to download image files and check/replace batteries. The remaining 24 cameras were stolen or damaged during the study period.
The 24-h activity patterns of all species were deduced from camera-trap photo and video records (Qi et al., 2015, Yang et al., 2018b). We analysed only photos taken at a minimum time interval of 30 minutes (Santos et al., 2019) to avoid pseudoreplication. Based on local climate characteristics, we defined two distinct periods: the winter period (snow period: Nov– Apr) and the summer period (snow-free period: May – Oct) (Table 1). The data processing was completed by specialists in Prof. Jiang Guangshun’s research teams at the Feline Research Center of National Forestry and Grassland and Administration (Northeast Forestry University) who completed species identification and data arrangement.