Behavioral "bycatch" from camera trap surveys yields insights on prey responses to human-mediated predation risk

Human disturbance directly affects animal populations but indirect effects of disturbance on species behaviors are less well understood. Camera traps provide an opportunity to investigate variation in animal behaviors across gradients of disturbance. We used camera trap data to test predictions about predator-sensitive behavior in three ungulate species (caribou Rangifer tarandus; white-tailed deer, Odocoileus virginianus; moose, Alces alces) across two boreal forest landscapes varying in disturbance. We quantified behavior as the number of camera trap photos per detection event and tested its relationship to predation risk between a landscape with greater industrial disturbance and predator abundance (Algar) and a "control" landscape with lower human and predator activity (Richardson). We also assessed the influence of predation risk and habitat on behavior across camera sites within the disturbed Algar landscape. We predicted that animals in areas with greater predation risk (more wolf activity, less cover) would travel faster and generate fewer photos per event, while animals in areas with less predation risk would linger (rest, forage), generating more photos per event. Consistent with predictions, caribou and moose had more photos per event in the landscape where predation risk was reduced. Within the disturbed landscape, no prey species showed a significant behavioral response to wolf activity, but the number of photos per event decreased for white-tailed deer with increasing line of sight (m) along seismic lines (i.e. decreasing visual cover), consistent with a predator-sensitive response. The presence of juveniles was associated with shorter behavioral events for caribou and moose, suggesting greater predator sensitivity for females with calves. Only moose demonstrated a positive association with vegetation productivity (NDVI), suggesting that for other species influences of forage availability were generally weaker than those from predation risk. Behavioral insights can be gleaned from camera trap surveys and provide information about animal responses to predation risk and the indirect impacts of human disturbances.

人类活动干扰可直接影响动物种群，但此类干扰对物种行为的间接效应却鲜少被深入阐明。相机陷阱（camera traps）为探究不同干扰梯度下的动物行为变异提供了研究契机。本研究借助相机陷阱数据，针对两种干扰程度各异的北方针叶林景观中的三种有蹄类动物（驯鹿*Rangifer tarandus*、白尾鹿*Odocoileus virginianus*、驼鹿*Alces alces*）的捕食敏感行为假说开展验证。本研究以单次检测事件内的相机陷阱拍摄照片数作为行为量化指标，对比了工业干扰更强、捕食者密度更高的阿尔加尔（Algar）景观，与人类及捕食者活动更低的"对照"景观（理查森（Richardson））之间的行为与捕食风险的关联。此外，本研究还针对受干扰的阿尔加尔景观内的各相机布设点位，评估了捕食风险与生境对动物行为的影响。我们提出如下假说：在捕食风险更高（狼活动更频繁、隐蔽条件更差）的区域，动物移动速度更快，单次检测事件内的拍摄照片数更少；而在捕食风险较低的区域，动物会更长时间停留（休息、觅食），单次检测事件内的拍摄照片数更多。研究结果与假说一致：在捕食风险降低的景观中，驯鹿与驼鹿的单次检测事件拍摄照片数更多。在受干扰的阿尔加尔景观内，所有猎物种群均未表现出对狼活动的显著行为响应，但白尾鹿的单次检测照片数随地震勘探线的视距（米）增加（即隐蔽性降低）而减少，这与捕食敏感行为的特征相符。幼崽的存在与驯鹿和驼鹿的单次行为事件时长更短相关，这表明带崽雌性个体对捕食者的敏感性更高。仅驼鹿表现出与植被生产力（归一化差分植被指数Normalized Difference Vegetation Index，NDVI）的正相关关系，这表明相较于捕食风险，其他有蹄类物种的觅食可获得性对其行为的影响普遍较弱。从相机陷阱调查中可获取动物行为相关的洞察，进而为理解动物对捕食风险的响应以及人类干扰的间接效应提供参考依据。