Data from: Disentangling woodland caribou movements in response to clearcuts and roads across temporal scales

Although prey species typically respond to the most limiting factors at coarse spatiotemporal scales while addressing biological requirements at finer scales, such behaviour may become challenging for species inhabiting human altered landscapes. We investigated how woodland caribou, a threatened species inhabiting North-American boreal forests, modified their fine-scale movements when confronted with forest management features (i.e. clearcuts and roads). We used GPS telemetry data collected between 2004 and 2010 on 49 female caribou in a managed area in Québec, Canada. Movements were studied using a use – availability design contrasting observed steps (i.e. line connecting two consecutive locations) with random steps (i.e. proxy of immediate habitat availability). Although caribou mostly avoided disturbances, individuals nonetheless modulated their fine-scale response to disturbances on a daily and annual basis, potentially compromising between risk avoidance in periods of higher vulnerability (i.e. calving, early and late winter) during the day and foraging activities in periods of higher energy requirements (i.e. spring, summer and rut) during dusk/dawn and at night. The local context in which females moved was shown to influence their decision to cross clearcut edges and roads. Indeed, although females typically avoided crossing clearcut edges and roads at low densities, crossing rates were found to rapidly increase in greater disturbance densities. In some instance, however, females were less likely to cross edges and roads as densities increased. Females may then be trapped and forced to use disturbed habitats, known to be associated with higher predation risk. We believe that further increases in anthropogenic disturbances could exacerbate such behavioural responses and ultimately lead to population level consequences.

尽管被捕食物种通常在较粗的时空尺度上响应最关键的限制因子，同时在更精细的尺度上满足自身的生物学需求，但对于栖息在人为改造景观中的物种而言，这类行为模式可能会面临挑战。本研究针对栖息于北美北方针叶林的受胁物种——林地驯鹿（woodland caribou），探究其在面对森林经营活动形成的景观要素（即皆伐迹地与道路）时，如何调整其精细尺度的移动行为。我们使用了2004年至2010年间，在加拿大魁北克省某受经营管理区域内，对49头雌性驯鹿采集的GPS遥测数据。本研究采用利用-可获得性设计（use–availability design）开展移动行为分析，将观测得到的移动步距（即连接两个连续定位点的线段）与随机步距（即表征即时生境可获得性的替代指标）进行对比。尽管驯鹿大多会避开干扰区域，但个体仍会基于日周期与年周期调节其对干扰的精细尺度响应，在不同场景间进行权衡：日间于高脆弱性时期（即产羔期、冬初与冬末）规避捕食风险，而在能量需求较高的时期（即春季、夏季与发情期）于黄昏/黎明及夜间开展觅食活动。研究表明，雌性驯鹿移动的局域环境会影响其穿越皆伐迹地边缘与道路的决策。具体而言，尽管在干扰密度较低的情境下，雌性通常会避开穿越皆伐迹地边缘与道路，但当干扰密度升高时，其穿越率会快速上升。然而在部分情形中，随着干扰密度升高，雌性穿越边缘与道路的概率反而降低。此时雌性驯鹿可能陷入困境，被迫利用受干扰生境——而这类生境通常与更高的捕食风险相关。我们认为，人为干扰的进一步加剧可能会恶化这类行为响应，最终对种群水平产生负面影响。