1. Unmanned aerial vehicles (UAVs) are increasingly important in wildlife data collection but concern over wildlife disturbance has led several countries to ban their use in National Parks. Disturbance is an animal welfare concern and impedes scientific data collection through provoking aberrant behaviour. Dealing with the issue of disturbance will enable wildlife researchers to use UAV technology more effectively and ethically.
2. Here we present a novel method to determine optimal flight altitude for minimising drone disturbance for wildlife using species audiograms. We recorded sound profiles of seven common UAV systems in the horizontal and vertical planes at 5-m increments up to 120 m. To understand how mammals perceive UAV sound, we used audiograms of 20 species to calculate the loudness of each UAV for each species across the measured distances. These calculations filter the UAV noise based on the sensitivity of species’ hearing over the relevant frequency spectrum.
3. We have devised a method to optimise the trade-off between image spatial resolution and flight altitude. We calculated the lowest point at which either the UAV sound level decreases below an acceptable threshold, here chosen as 40 dB, weighted according to species’ hearing sensitivity, or disturbance cannot be significantly further minimised by flying higher. The latter is quantified as the point above which each additional 5 m of flight altitude causes on average less than 0.05 dB decrease in sound pressure level.
4. Reliable data on appropriate flight altitudes can guide policy regulations on flying UAVs over wildlife, thus enabling increased use of this technology for scientific data collection and for wildlife conservation purposes. The methodology is readily applicable to other species and UAV systems for which sound recordings and audiograms are available.

中文翻译：

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使用物种听力图确定最佳飞行高度以最大限度地减少无人机对野生动物的干扰

1. 无人机 (UAV) 在野生动物数据收集中越来越重要，但对野生动物干扰的担忧导致多个国家禁止在国家公园使用无人机。干扰是一个动物福利问题，会通过引发异常行为来阻碍科学数据的收集。处理干扰问题将使野生动物研究人员能够更有效、更合乎道德地使用无人机技术。
2. 在这里，我们提出了一种使用物种听力图确定最佳飞行高度的新方法，以最大限度地减少无人机对野生动物的干扰。我们在水平和垂直平面上以 5 米至 120 米的增量记录了七种常见无人机系统的声音剖面。为了了解哺乳动物如何感知无人机声音，我们使用了 20 个物种的听力图来计算每个物种在测量距离上的每个无人机的响度。这些计算根据物种在相关频谱上的听觉灵敏度过滤无人机噪声。
3. 我们设计了一种方法来优化图像空间分辨率和飞行高度之间的权衡。我们计算了最低点，在该点无人机声级降低到可接受的阈值以下，此处选择为 40 dB，根据物种的听力灵敏度加权，或者不能通过飞得更高来进一步显着减少干扰。后者被量化为每增加 5 m 飞行高度导致声压级平均降低小于 0.05 dB 的点。
4. 适当飞行高度的可靠数据可以指导无人机在野生动物上空飞行的政策规定，从而使这项技术能够更多地用于科学数据收集和野生动物保护目的。该方法很容易适用于其他物种和 UAV 系统，这些系统可以提供录音和听力图。