Advances in Large-Scale Surveying and Monitoring of Large Wild Animals Using Unmanned Aerial Vehicles

As the number of endangered animal species increases, their conservation requires effective methods for the surveying and monitoring of the spatial and temporal distributions of targeted species, often on a large scale. Traditional methods often fail to meet the requirements for effective, large-scale surveying and monitoring due to inherent limitations. The use of unmanned aerial vehicles (UAVs) for wild animal surveys presents a promising alternative to traditional ground-based methods, particularly for large-scale monitoring. However, its application has been predominantly limited to open landscapes, leaving a significant gap for surveys in complex, forested environments that host numerous elusive and endangered large vertebrate species. This review synthesizes recent advancements and critically assesses the challenges of UAV-based surveys for large vertebrates. We systematically evaluate suitable survey strategies (e.g., absolute/relative and overall/sampling), platform types (fixed-wing vs. rotary-wing), and airborne detectors (RGB, thermal, and multispectral) for different contexts. We conclude that the future of large-scale wildlife monitoring in rugged, mountainous regions relies on the integration of three key technologies: (1) developing long-endurance UAV platforms, (2) employing multi-spectral detection equipment to acquire multimodal data, and (3) establishing efficient, artificial intelligence-driven data processing pipelines. By addressing these priorities, UAV technology can fully realize its potential to provide accurate, efficient, and non-invasive monitoring solutions for large vertebrate populations in their most challenging habitats.