Testing camera traps as a potential tool for detecting nest predation of birds in a tropical rainforest environment

ABSTRACT Identification of the predators of bird nests is essential to test ecological and evolutionary hypotheses and to make practical management decisions. A variety of nest monitoring devices have been proposed but many remain difficult to set up in the field. The aim of this study was to test camera traps as a potential tool to study predation of natural nests in a tropical rainforest environment. Specifically, we registered the predators, assessed their size range, and we compared the use of one and two cameras per nest. Of 122 nests from 24 bird species, 45 (37%) were depredated, and the cameras recorded the predator species in 29 of the total of depredated nests (64%). We identified predators in eight of 16 depredated nests (50%) in which we used one camera trap per nest, and we identified predators in 21 of 29 depredated nests (72%) when we used two camera traps per nest. The predators included six species of birds and six species of mammals, with body masses varying from 20 g to 16.5 kg. Causes for 10 of the 16 detection failures were identified and are discussed. These results suggest that camera traps are viable tools to investigate nest predation in a tropical rainforest area.摘要：识别鸟巢捕食者，对于验证生态学与进化学假说、制定实际管理决策均至关重要。目前已提出多种鸟巢监测设备，但其中多数难以在野外部署。本研究旨在验证相机陷阱（camera traps）作为研究热带雨林生境中天然鸟巢捕食行为的潜在工具的可行性。具体而言，本研究记录了捕食者类群，评估了其体型范围，并对比了每个鸟巢布设1台与2台相机陷阱的效果差异。在来自24种鸟类的122个鸟巢中，共有45个（占比37%）遭到捕食，其中29个被捕食鸟巢（占总被捕食巢的64%）的捕食者物种被相机陷阱记录到。在每个鸟巢布设1台相机陷阱的16个被捕食巢中，我们成功识别出8个（占比50%）的捕食者；而在布设2台相机陷阱的29个被捕食巢中，成功识别出21个（占比72%）的捕食者。本次研究识别出的捕食者包括6种鸟类与6种哺乳动物，其体重范围为20克至16.5千克。16次检测失败中的10次原因已被查明并将在文中展开讨论。上述结果表明，相机陷阱是开展热带雨林区域鸟巢捕食行为研究的可行工具。