Assessing the effects of industrial development on wildlife is a key objective of managers and conservation practitioners. However, wildlife responses are often only investigated with respect to the footprint of infrastructure, even though human activity can strongly mediate development impacts. In Arctic Alaska, there is substantial interest in expanding energy development, raising concerns about the potential effects on barren-ground caribou (Rangifer tarandus granti). While caribou generally avoid industrial infrastructure, little is known about the role of human activity in moderating their responses, and whether managing activity levels could minimize development effects. To address this uncertainty, we examined the influence of traffic volume on caribou summer space use and road crossings in the Central Arctic Herd within the Kuparuk and Milne Point oil fields on the North Slope of Alaska. We first modeled spatiotemporal variation in hourly traffic volumes across the road system from traffic counter data using gradient-boosted regression trees. We then used generalized additive models to estimate nonlinear step selection functions and road-crossing probabilities from collared female caribou during the post-calving and insect harassment seasons, when they primarily interact with roads. Step selection analyses revealed that caribou selected areas further from roads (~1–3 km) during the post-calving and mosquito seasons and selected areas with lower traffic volumes during all seasons, with selection probabilities peaking when traffic was <5 vehicles/h. Using road-crossing models, we found that caribou were less likely to cross roads during the insect seasons as traffic increased, but that response dissipated as insect harassment became more severe. Past studies suggested that caribou exhibit behavioral responses when traffic exceeds 15 vehicles/h, but our results demonstrate behavioral responses at much lower traffic levels. Our results illustrate that vehicle activity mediates caribou responses to road infrastructure, information that can be used in future land-use planning to minimize the behavioral responses of caribou to industrial development in sensitive Arctic landscapes.

中文翻译：

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车辆交通对北极驯鹿空间利用和道路穿越的影响

评估工业发展对野生动物的影响是管理者和保护从业者的一个关键目标。然而，尽管人类活动可以强烈调节发展影响，但野生动物的反应通常只针对基础设施的足迹进行调查。在阿拉斯加北极地区，人们对扩大能源开发抱有浓厚兴趣，这引发了人们对这对贫瘠土地驯鹿（Rangifer tarandus granti）的潜在影响的担忧。虽然驯鹿通常避开工业基础设施，但人们对人类活动在调节其反应方面的作用以及管理活动水平是否可以最大限度地减少发展影响知之甚少。为了解决这种不确定性，我们研究了交通量对阿拉斯加北坡库帕鲁克和米尔恩角油田内北极中部驯鹿群夏季空间利用和道路交叉口的影响。我们首先使用梯度增强回归树根据交通计数器数据对整个道路系统每小时交通量的时空变化进行建模。然后，我们使用广义加性模型来估计带项圈雌性驯鹿在产犊后和昆虫骚扰季节（当它们主要与道路相互作用时）的非线性步骤选择函数和穿越道路的概率。步骤选择分析显示，驯鹿在产犊后和蚊子季节选择远离道路的区域（约1-3公里），并选择所有季节交通量较低的区域，当交通量<5辆车/小时时选择概率达到峰值。使用过马路模型，我们发现，在昆虫季节，随着交通量的增加，驯鹿过马路的可能性较小，但随着昆虫骚扰变得更加严重，这种反应就会消失。过去的研究表明，当交通量超过 15 辆车/小时时，驯鹿会表现出行为反应，但我们的结果表明，交通量水平低得多时，驯鹿会表现出行为反应。我们的结果表明，车辆活动调节驯鹿对道路基础设施的反应，这些信息可用于未来的土地利用规划，以尽量减少驯鹿对敏感北极地区工业发展的行为反应。