Data from: Moose movement rates are altered by wolf presence in two ecosystems

Predators directly impact prey populations through lethal encounters, but
understanding non-lethal, indirect effects is also critical because
foraging animals often face tradeoffs between predator avoidance and
energy intake. Quantifying these indirect effects can be difficult even
when it is possible to monitor individuals that regularly interact. Our
goal was to understand how movement and resource selection o a predator
(wolves; Canis lupus) influences the movement behavior of a prey species
(moose; Alces alces). We tested whether moose avoided areas with high
predicted wolf resource use in two study areas with differing prey
compositions, whether avoidance patterns varied seasonally, and whether
daily activity budgets of moose and wolves aligned temporally. We deployed
GPS-collars on both species at two sites in northern Minnesota. We created
seasonal resource-selection functions (RSF) for wolves and modeled the
relationship between moose first-passage time (FPT), a method that
discerns alterations in movement rates, and wolf RSF values. Larger FPT
values suggest rest/foraging, whereas shorter FPT values indicate
travel/fleeing. We found that the movements of moose and wolves peaked at
similar times of day in both study areas. Moose FPTs were 45% lower in
areas most selected for by wolves relative to those avoided. The
relationship between wolf RSF and moose FPT was nonlinear and varied
seasonally. Differences in FPT between low and high RSF values were
greatest in winter (-82.1%) and spring (-57.6%) in northeastern Minnesota
and similar for all seasons in the Voyageurs National Park ecosystem. In
northeastern Minnesota, where moose comprise a larger percentage of wolf
diet, the relationship between moose FPT and wolf RSF was more pronounced
(ave. across seasons: -60.1%) than the Voyageurs National Park ecosystem
(-30.4%). These findings highlight the role wolves can play in determining
moose behavior, whereby moose spend less time in areas with higher
predicted likelihood of wolf resource selection.

捕食者可通过致死性遭遇直接影响猎物种群，但理解非致死性间接效应同样至关重要——觅食动物往往需要在捕食者规避与能量摄入之间进行权衡。即便能够对存在经常性交互的个体开展监测，量化这类间接效应往往也颇具难度。
本研究旨在探究捕食者（灰狼（Canis lupus））的移动模式与资源选择行为，如何影响猎物种群（驼鹿（Alces alces））的移动行为。
我们在两个猎物组成存在差异的研究区域内，开展了三项检验：其一，驼鹿是否会规避灰狼资源利用概率较高的区域；其二，此类规避模式是否随季节发生变化；其三，驼鹿与灰狼的每日活动时间预算是否在时间维度上匹配一致。
我们在明尼苏达州北部的两个研究位点，为两个物种的个体佩戴了GPS项圈（GPS collar）。
我们为灰狼构建了季节尺度的资源选择函数（resource-selection functions, RSF），并针对驼鹿首次通过时间（first-passage time, FPT）——一种用以识别移动速率变化的方法——与灰狼资源选择函数值之间的关联开展建模。
FPT值越高，代表驼鹿处于休息/觅食状态；反之FPT值越低，则代表驼鹿正在行进/逃逸。
研究发现，在两个研究区域内，驼鹿与灰狼的活动峰值均出现在每日的相近时段。
相较于驼鹿规避的区域，灰狼优先选择的区域内的驼鹿FPT值降低了45%。
灰狼资源选择函数值与驼鹿FPT值之间的关联呈非线性特征，且随季节发生变化。
在明尼苏达州东北部，低资源选择函数值与高资源选择函数值区域内的驼鹿FPT差值在冬季（-82.1%）与春季（-57.6%）达到最大；而在Voyageurs国家公园生态系统中，该差值在所有季节均无显著差异。
在明尼苏达州东北部，驼鹿在灰狼食谱中的占比更高，因此驼鹿FPT与灰狼资源选择函数值之间的关联比Voyageurs国家公园生态系统中更为显著（全季节平均降幅为-60.1%，后者为-30.4%）。
本研究结果证实了灰狼在调控驼鹿行为中发挥的关键作用：驼鹿会在灰狼资源利用概率较高的区域花费更少的时间。