Remote‐controlled, unmanned aerial vehicles (UAVs) can be used to collect information in difficult‐to‐access places while potentially minimizing human disturbance. These devices have been widely used in a variety of ecological and behavioral studies in recent years, but additional study is needed to assess the magnitude of disturbance they cause to birds. We examined the responses of Great Egrets (Ardea alba) to a UAV in a breeding colony in Louisiana in 2016 where isolated patches of common reed (Phragmites australis) were used as nest sites by multiple breeding pairs. We examined the flush responses and flight initiation distances (FIDs) of nesting adults to the direct vertical approach of a UAV. Incubating adults were more likely to flush from nests and flushed at greater distances when approached by a UAV than adults with nestlings, suggesting that adult assessment of risk was based on the greater reproductive value of nestlings. We observed fewer flush responses and calculated lower set‐back distances using a UAV to approach nesting Great Egrets (~50 m) than set‐back distances calculated using traditional methods of approach (e.g., walking or boating; 87–251 m). We found that FIDs were shorter when more adults were present in nesting patches, suggesting that the perception of predation risk may be based in part on the reactions of other birds. Our results suggest that UAVs may be a useful alternative for monitoring colonial‐nesting waterbirds. However, our analyses were based exclusively on behavioral observations. Additional studies of the physiological responses of birds to the approach of UAVs are needed to better understand the stress responses of birds to these devices.

中文翻译：

---

使用飞行起始距离来评估殖民地大白鹭对无人驾驶飞机进近的反应

遥控无人飞行器（UAV）可用于在难以进入的地方收集信息，同时有可能将人为干扰降到最低。近年来，这些设备已广泛用于各种生态和行为研究中，但是还需要进行其他研究来评估它们对鸟类造成的干扰程度。我们在2016年路易斯安那州的一个繁殖种群中检查了大白鹭（UAE ALBA）对无人机的反应，那里有孤立的常见芦苇斑（芦苇））被多个繁殖对用作筑巢地点。我们检查了成年成鸟对无人机直接垂直进近的平齐响应和飞行起始距离（FID）。与无雏鸟的成年鸟相比，被无人机孵化的成年鸟更容易从巢中冲出并且被冲走的距离更大，这表明成年鸟的风险评估是基于雏鸟的更高繁殖价值。与使用传统进近方法（例如，步行或划船； 87-251 m）计算出的后退距离相比，我们观察到使用无人机接近嵌套的大白鹭（〜50 m）时，冲洗响应更少，并且计算出的后退距离更低。我们发现，当更多的成年鸟出现在筑巢区时，FID会变短，这表明对捕食风险的感知可能部分基于其他鸟类的反应。我们的结果表明，无人机可能是监测殖民地筑巢的水鸟的有用选择。但是，我们的分析仅基于行为观察。为了更好地了解鸟类对这些设备的应激反应，还需要对鸟类对无人机的生理反应进行更多研究。