Refuge or predation risk? Alternate ways to perceive hiker disturbance based on maternal state of female caribou

Human presence in natural environments is often a source of stress that is perceived by large ungulates as an increased risk of predation. Alternatively, disturbance induced by hikers creates a relatively predator-free space that may serve as a refuge. We measured the behavioral responses of female caribou to disturbance associated with the presence of hikers during summer in the Gaspésie National Park. We used those data to determine whether caribou responded negatively to human activity (i.e., the predation risk hypothesis) or whether human activity resulted in a decrease in the magnitude of perceived risk (i.e., the refuge hypothesis). Female caribou with a calf spent nearly half of their time feeding, regardless of the presence of a trail or the number of hikers. They also decreased their vigilance near trails when the number of hikers increased. Conversely, lone females fed less frequently and almost doubled the time invested in vigilance under the same circumstances. However, both...自然环境中的人类活动与在场往往会成为应激源，大型有蹄类动物（large ungulates）会将其视作捕食风险升高的信号。与之相对的是，徒步旅行者（hikers）引发的干扰会创造出一处相对无捕食者的空间，可作为庇护所。本研究于夏季在加斯佩西国家公园（Gaspésie National Park）开展，我们监测了雌性北美驯鹿（caribou）针对徒步者在场所引发的干扰所做出的行为响应。我们利用这些数据，旨在验证两种对立假说：其一为人类活动会使北美驯鹿产生负面响应的捕食风险假说（predation risk hypothesis），其二为人类活动会降低北美驯鹿所感知到的风险强度的庇护所假说（refuge hypothesis）。带有幼崽的雌性北美驯鹿几乎会将一半时间用于觅食，无论步道是否存在、或是徒步者的数量多少。随着徒步者数量增多，它们在步道附近的警戒行为也会有所减少。与之相反，独居的雌性北美驯鹿则会减少觅食频率，且在相同条件下，用于警戒的时间几乎增加了一倍。然而，两类……