Jones Landon R, Mensah Cerise, Elmore Jared A, Evans Kristine O, Pfeiffer Morgan B, Blackwell Bradley F, Iglay Raymond B
Department of Wildlife, Fisheries, and Aquaculture, Mississippi State University, Mississippi State, MS 39762, USA.
Museum of Natural Science, Mississippi Department of Wildlife, Fisheries, and Parks, Jackson, MS 39202, USA.
MethodsX. 2024 Aug 30;13:102933. doi: 10.1016/j.mex.2024.102933. eCollection 2024 Dec.
Thermal sensors mounted on drones (unoccupied aircraft systems) are popular and effective tools for monitoring cryptic animal species, although few studies have quantified sampling error of animal counts from thermal images. Using decoys is one effective strategy to quantify bias and count accuracy; however, plastic decoys do not mimic thermal signatures of representative species. Our objective was to produce heat signatures in animal decoys to realistically match thermal images of live animals obtained from a drone-based sensor. We tested commercially available methods to heat plastic decoys of three different size classes, including chemical foot warmers, manually heated water, electric socks, pad, or blanket, and mini and small electric space heaters. We used criteria in two categories, 1) external temperature differences from ambient temperatures (ambient difference) and 2) color bins from a palette in thermal images obtained from a drone near the ground and in the air, to determine if heated decoys adequately matched respective live animals in four body regions. Three methods achieved similar thermal signatures to live animals for three to four body regions in external temperatures and predominantly matched the corresponding yellow color bins in thermal drone images from the ground and in the air. Pigeon decoys were best and most consistently heated with three-foot warmers. Goose and deer decoys were best heated by mini and small space heaters, respectively, in their body cavities, with a heated sock in the head of the goose decoy. The materials and equipment for our best heating methods were relatively inexpensive, commercially available items that provide sustained heat and could be adapted to various shapes and sizes for a wide range of avian and mammalian species. Our heating methods could be used in future studies to quantify bias and validate methodologies for drone surveys of animals with thermal sensors.•We determined optimal heating methods for plastic animal decoys with inexpensive and commercially available equipment to mimic thermal signatures of live animals.•Methods could be used to quantify bias and improve thermal surveys of animals with drones in future studies.
安装在无人机（无人飞行器系统）上的热传感器是监测隐秘动物物种的常用且有效的工具，尽管很少有研究对热图像中动物数量的采样误差进行量化。使用诱饵是量化偏差和计数准确性的一种有效策略；然而，塑料诱饵无法模拟代表性物种的热信号。我们的目标是在动物诱饵中产生热信号，使其与从基于无人机的传感器获取的活体动物热图像真实匹配。我们测试了市售的加热三种不同尺寸塑料诱饵的方法，包括化学暖脚器、手动加热水、电袜子、垫子或毯子，以及小型和微型电暖器。我们使用两类标准来确定加热后的诱饵在四个身体部位是否与相应的活体动物充分匹配，这两类标准分别是：1）与环境温度的外部温差（环境温差），以及2）从地面和空中靠近无人机获取的热图像调色板中的颜色区间。三种方法在外部温度下，能使三到四个身体部位的热信号与活体动物相似，并且在地面和空中的热无人机图像中，主要与相应的黄色颜色区间匹配。用三个暖脚器加热鸽子诱饵效果最佳且最稳定。鹅和鹿的诱饵分别在其体腔内用微型和小型电暖器加热效果最佳，鹅诱饵头部用加热袜子加热。我们最佳加热方法所需的材料和设备相对便宜，是可提供持续热量的市售物品，并且可以根据各种鸟类和哺乳动物的不同形状和大小进行调整。我们的加热方法可用于未来的研究，以量化偏差并验证使用热传感器对动物进行无人机调查的方法。
•我们用便宜且市售的设备确定了塑料动物诱饵的最佳加热方法，以模拟活体动物的热信号。
•这些方法可用于量化偏差，并在未来的研究中改进对动物的无人机热成像调查。
