A systematic review of global road ecology camera trap studies that monitored animals’ use of wildlife crossings in road-fragmented landscapes

Much research has emphasised the importance of incorporating wildlife crossing-structures in the design of road networks to facilitate connectivity of wildlife crossings in road-fragmented landscapes. Although camera traps have been effective in monitoring wildlife crossing structures, limited studies explore camera trap protocol to monitor wildlife use of crossing structures, particularly in Africa. Our study reviewed and assessed camera trap peer-reviewed research that monitored the use of crossing-structures by wildlife to navigate landscapes fragmented by roads. We found 70 camera trap peer-reviewed publications from 2001 to 2022 that monitored wildlife use of crossing-structures in landscapes intersected by roads, and these were from 22 countries and six continents. The included peer-reviewed studies varied significantly globally, with geographical trends indicating that most studies were conducted in North America. However, the methods used varied considerably between studies, especially in terms of camera trap placement protocol (placement height of camera trap, survey length, and camera multi-shot settings). This showed that camera trap usage for monitoring animal use of crossing structures is still an emerging area of research, and there is a potential for developing a standardised protocol for each type of crossing structure design and size. Future camera trap studies exploring wildlife use of crossing-structures should consider monitoring existing crossing structures (culverts, bridges, and tunnels) as this provides a less costly method of restoring landscape connectivity. We recommend that further research develop a standardised camera trap protocol for monitoring wildlife using crossing-structures to reduce the threats to biodiversity.大量研究均强调，在道路网络设计中纳入野生动物过境通道（wildlife crossing-structures），对维系道路破碎化景观中野生动物的迁徙连通性具有关键意义。尽管相机陷阱（camera traps）已被证实可有效监测野生动物对过境通道的利用情况，但针对该应用场景的相机陷阱监测方案的探索性研究仍较为匮乏，在非洲地区尤其如此。本研究对已发表的同行评议文献进行了系统综述与评估，这些文献聚焦于监测野生动物借助过境通道穿越道路破碎化景观的行为。我们共检索得到2001年至2022年间发表的70篇相关同行评议论文，这些研究覆盖六大洲的22个国家，均针对道路割裂的景观中野生动物对过境通道的使用情况开展监测。全球范围内的相关研究存在显著异质性：地理分布趋势显示，绝大多数研究集中于北美地区。同时，不同研究所采用的方法差异显著，尤其体现在相机陷阱布设方案层面，包括相机布设高度、调查时长与连拍设置等维度。这表明，利用相机陷阱监测动物过境通道使用情况仍是一个新兴研究领域，针对不同类型与尺寸的过境通道设计标准化监测方案具备巨大发展潜力。未来开展野生动物过境通道使用情况监测的相机陷阱研究，应优先考虑对现有过境通道（涵洞、桥梁与隧道）进行监测，该方法可为景观连通性修复提供更为经济高效的路径。我们建议，后续研究应进一步开发标准化的相机陷阱监测方案，以实现对利用过境通道的野生动物的有效监测，从而降低生物多样性面临的威胁。