Birds that nest on the ground in open areas, such as Piping Plovers (Charadrius melodus) and Interior Least Terns (Sternula antillarum athalassos), are exposed to high temperatures in thermally stressful environments. As a result, some ground-nesting avian species have adapted behavioral strategies to maintain thermal regulation of eggs and themselves. We assessed the impact of sand temperature on shorebird nesting behaviors by installing video cameras and thermocouples at 52 Least Tern and 55 Piping Plover nests on the Missouri River in North Dakota during the 2014-2015 breeding seasons. Daily duration and frequency of shading behaviors exhibited a nonlinear relationship with temperature; therefore, we used segmented regressions to determine at what threshold temperature (mean temperature = 25.7⸰C for shading behavior daily frequency and mean temperature = 25.1⸰C for shading behavior daily duration) shorebird adults exhibited a behavioral response to rising sand temperatures. Daily nest attendance of both species decreased with increasing sand temperatures in our system. Frequency and duration of daily shading behaviors were positively correlated with sand temperatures above the temperature threshold. Piping Plovers exhibited more and longer shading behaviors above and below the temperature thresholds (below: frequency = 10.30 ± 1.69 se, duration = 7.29 min ± 2.35 se; above: frequency = 59.27 ± 6.87 se) compared to Least Terns (below: frequency = -1.37 ± 1.98 se, duration = -0.73 min ± 1.51 se; above: frequency = 31.32 ± 7.29 se). The effects of sand temperature on avian ground-nesting behavior will be critical to understand in order to adapt or develop recovery plans in response to climate change.

中文翻译：

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Least Tern和Piping Plover筑巢行为响应沙温的可塑性

在开放区域的地面上筑巢的鸟类，如管道鸻（Charadrius melodus）和室内最小燕鸥（Sternula antillarum athalassos），在热应激环境中暴露在高温下。因此，一些地面筑巢的鸟类物种已经调整了行为策略来维持鸡蛋和它们自身的热调节。我们通过在 2014-2015 年繁殖季节在北达科他州密苏里河上的 52 个 Least Tern 和 55 个管道鸻鸟巢中安装摄像机和热电偶来评估沙温对滨鸟筑巢行为的影响。日遮阳行为的持续时间和频率与温度呈非线性关系；因此，我们使用分段回归来确定阈值温度（平均温度 = 25。7⸰C 遮阳行为每日频率和平均温度 = 25.1⸰C 遮阳行为每日持续时间）滨鸟成年人对沙温升高表现出行为反应。随着我们系统中沙温的升高，这两种物种的每日筑巢人数减少。每日遮荫行为的频率和持续时间与高于温度阈值的沙温呈正相关。与 Least Terns（低于：频率 = 7.29 min ± 2.35 se；以上：频率 = 59.27 ± 6.87 se）相比，管道鸻在温度阈值上下表现出更多和更长的遮蔽行为（以下：频率 = 10.30 ± 1.69 se，持续时间 = 7.29 min ± 2.35 se -1.37 ± 1.98 秒，持续时间 = -0.73 分钟 ± 1.51 秒；以上：频率 = 31.32 ± 7.29 秒）。