1. Camera traps are useful for monitoring wildlife populations, but traps may not always trigger when targeting small, nocturnal species. Motion-detection techniques have advantages over time-lapse and heat-triggered traps, but need to be deployed to maximize signal-to-noise ratio.
2. As part of a study of flying squirrels (Glaucomys) in urban environments we developed motion-detecting camera traps using a raspberry pi microcomputer and camera and a 940 nm IR illuminator on a tree-mounted wooden platform. The system was built from commercially available parts and was comparable in cost to a consumer camera trap, although this cost did not include a waterproof housing. We compared the performance of our system to commercial trailcams.
3. Four pi cameras successfully documented visits by Glaucomys and other animals to bait placed on the platform over three nights at four wooded sites: suburban and rural backyards, a private outdoors club and a small urban nature reserve (16 camera X site combinations, 48 trap nights). The traps showed low latency, with an average of <1 night until detection of Glaucomys at each site. Data collected had a high signal-to-noise ratio; of 2,182 capture events 55% documented Glaucomys, 40% documented non-target mammals, 1% were caused by large insects and the remaining 4% were unknown. Commercial camera traps placed at the sites failed to capture many of these events.
4. The low cost and high signal-to-noise ratio of this system may make it easy to adapt for other small animal applications. The main modification required to deploy this system in new situations will be in locating or providing a fixed or static background against which animals can be observed and in using masking techniques within motion-detection software.

中文翻译：

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一种基于运动检测的相机陷阱，适用于具有低延迟和高信噪比的小型夜间哺乳动物

1. 相机陷阱对于监测野生动物种群很有用，但在瞄准小型夜间物种时，陷阱可能并不总是触发。运动检测技术比延时和热触发陷阱具有优势，但需要部署以最大化信噪比。
2. 作为城市环境中飞鼠 ( Glaucomys )研究的一部分，我们在树上安装的木制平台上使用覆盆子 pi 微型计算机和相机以及 940 nm IR 照明器开发了运动检测相机陷阱。该系统由市售部件构成，其成本与消费者相机陷阱相当，但该成本不包括防水外壳。我们将我们系统的性能与商业追踪摄像头进行了比较。
3. 四个 pi 摄像机成功地记录了Glaucomys和其他动物在三个晚上在四个树木繁茂的地点对放置在平台上的诱饵的访问：郊区和农村后院、一个私人户外俱乐部和一个小型城市自然保护区（16 个摄像机 X 站点组合，48 个陷阱之夜） ）。陷阱显示出低延迟，平均 <1 晚，直到在每个站点检测到青光眼。收集的数据具有高信噪比；在 2,182 次捕获事件中，55% 被记录为青光眼，40% 被记录为非目标哺乳动物，1% 是由大型昆虫引起的，其余 4% 是未知的。放置在现场的商业相机陷阱未能捕捉到其中的许多事件。
4. 该系统的低成本和高信噪比使其易于适应其他小动物应用。在新情况下部署该系统所需的主要修改将是定位或提供固定或静态背景以观察动物，并在运动检测软件中使用掩蔽技术。