Off-channel aquatic habitat use by river otters and other vertebrates in the Central Platte River Valley, NE

We employed a multi-camera non-linear array sampling design to understand river otter habitat-use patterns in natural and artificial off-channel wetlands along the Platte River. We surveyed 10 off-channel aquatic habitats between 13 February to 15 October 2019. The sites were comprised of 5 pond and 5 slough sites. Each site consisted of a 100-130-meter non-linear array of 3 camera traps placed on existing wildlife trails along the banks of an off-channel aquatic habitat. Individual cameras were spaced between 40 and 75 meters apart within each array, depending upon conditions (availability of animal trails and appropriate topography). Habitat variables were collected at two spatial scales including the macrosite (broader aquatic environment; n = 10) and the microsite (trail along terrestrial-aquatic boundary; n = 30). In addition to documenting river otter occurrences, we recorded all identifiable vertebrate species from camera trap surveys. Therefore, this database has habitat modeling value for a range of other species including mammals such as the American Mink (Neovison vison), American Beaver (Castor canadensis), and Muskrat (Ondatra zibethicus) as well as birds such as the Great Blue Heron (Ardea herodias) or Canada goose (Branta canadensis). Some habitat variables are congruent across spatial scales and others differ. Macrosite habitat variables included maximum and average water depth (m), total water surface area (ac), water pH, water total hardness, mean distance to the river (m), mean distance to dirt road (m), mean distance to paved road (m), mean distance highway (m), mean distance to building (m), mean distance to woodland (m), mean vegetation cover across multiple height classes, the proportional cover of graminoids, forbs, woody species, and groundcover as litter. Microsite variables included all the same distance and vegetation cover metrics but also included bank slope, bank height (m), and control variables like the trail camera height and distance of the camera to the trail. The wetland depth profile was not considered at the microsite level as it reflected features of the larger waterbody. We included river otter scat detection as a validation technique for our river otter relative use metrics which included river otter presence/absence, total river otter captures per camera month, river otter young presence/absence, and river otter young captures per camera month.本研究采用多摄像头非线性阵列采样设计，以探究普拉特河（Platte River）沿岸天然与人工河道外湿地的河獭栖息地利用模式。本研究于2019年2月13日至10月15日期间，对10处河道外水生栖息地开展调查。本次调查样地包含5处池塘与5处缓水沼泽样地。每处样地均布设由3台相机陷阱（camera trap）组成的100-130米非线性阵列，相机安置于河道外水生栖息地沿岸现存的野生动物步道上。各阵列内单台相机的布设间距为40至75米，具体间距根据实际条件（野生动物步道可获得性与适宜地形）调整。栖息地变量的采集采用两类空间尺度：宏样地（macrosite，即更广阔的水生环境，样本量n=10）与微样地（microsite，即水陆交界沿线步道，样本量n=30）。除记录河獭的出现情况外，本研究还通过相机陷阱调查记录了所有可识别的脊椎动物物种。因此，本数据集可为一系列其他物种的栖息地建模提供支撑，涵盖哺乳类与鸟类：哺乳类包括美洲水鼬（Neovison vison）、美洲河狸（Castor canadensis）与麝鼠（Ondatra zibethicus）；鸟类则包括大蓝鹭（Ardea herodias）与加拿大黑雁（Branta canadensis）。部分栖息地变量在两类空间尺度上保持一致，其余变量则存在差异。宏样地的栖息地变量包括：最大水深与平均水深（单位：米）、总水面面积（单位：英亩，ac）、水体pH值、水体总硬度、至主河道的平均距离（单位：米）、至土路的平均距离（单位：米）、至铺装路的平均距离（单位：米）、至高速公路的平均距离（单位：米）、至建筑物的平均距离（单位：米）、至林地的平均距离（单位：米）、多高度层级的平均植被覆盖度、禾本科植物占比、非禾本草本植物占比、木本植物占比以及枯落物地表覆盖占比。微样地变量则涵盖全部相同的距离与植被覆盖度量指标，此外还包括岸坡坡度、岸高（单位：米），以及步道相机高度、相机与步道间距等控制变量。由于湿地水深剖面反映的是更大水体的特征，因此未在微样地尺度下采集该变量。本研究以河獭粪便检测作为河獭相对利用指标的验证方法，河獭相对利用指标包括河獭存在/缺失情况、每相机月的河獭总捕获次数、幼獭存在/缺失情况以及每相机月的幼獭捕获次数。