supplementary data file from Foraging behaviour, habitat use and population size of the desert horned viper in the Negev desert

The desert horned viper occurs in the dunes of the northwestern Negev desert, Israel. We report on a 2-year study on the viper's behaviour and ecology in its natural habitat. We examined whether the vipers moved faster in a vegetation-dense microhabitat versus an open dune area and detected much slower movement in the former. We nevertheless detected no preference of the vipers for any of the dune areas. We suggest that the vipers trade-off the ease of movement on open areas with prey, which is probably more available in areas with denser vegetation. The activity was higher early in the season and the vipers were mostly active right after sunset, with a second smaller activity peak at sunrise, perhaps searching for burrows to spend the day. Fitting this explanation, movement at the track's end was less directional than at its beginning. We found inter-sexual and between-year differences. For example, females were larger than males in the second year of the study but not in the first one and the population seemed to be smaller in the second year of the study than in its first year. The information we provide on this viper may assist its conservation, as sand dunes are threatened habitats in Israel.

沙漠角蝰（desert horned viper）栖息于以色列内盖夫沙漠西北部的沙丘地带。本研究针对该物种在自然栖息地中的行为与生态特征开展了为期2年的调查。我们对比了该蝰蛇在植被密集微生境与开阔沙丘区域的移动速度，发现其在植被密集环境中的移动速度显著更慢。但研究未发现该蝰蛇对两类沙丘生境存在明显偏好。我们推测，该蝰蛇会在开阔区域的移动便利性与猎物可得性之间进行权衡——植被密集区域的猎物资源大概率更为丰富。该物种的活动强度在季初更高，且主要集中在日落后时段；日出时会出现第二个较小的活动高峰，此时它们或在寻找洞穴以度过日间。这一推论可得到佐证：移动轨迹末端的方向性相较于初始阶段更弱。研究还发现该种群存在性间差异与年际差异：例如，在研究第二年，雌性个体体型大于雄性，但第一年并未出现该现象；且研究第二年的种群规模似乎较第一年有所缩减。鉴于以色列的沙丘生境属于受威胁栖息地类型，本研究提供的相关数据可为该蝰蛇的保护工作提供助力。