Long‐term population studies can identify changes in population dynamics over time. However, to realize meaningful conclusions, these studies rely on accurate measurements of individual traits and population characteristics. Here, we evaluate the accuracy of the observational methods used to measure reproductive traits in individually marked black‐tailed godwits (Limosa limosa limosa). By comparing estimates from traditional methods with data obtained from light‐level geolocators, we provide an accurate estimate of the likelihood of renesting in godwits and the repeatability of the lay dates of first clutches. From 2012 to 2018, we used periods of shading recorded on the light‐level geolocators carried by 68 individual godwits to document their nesting behaviour. We then compared these estimates to those simultaneously obtained by our long‐term observational study. We found that among recaptured geolocator‐carrying godwits, all birds renested after a failed first clutch, regardless of the date of nest loss or the number of days already spent incubating. We also found that 43% of these godwits laid a second replacement clutch after a failed first replacement, and that 21% of these godwits renested after a hatched first clutch. However, the observational study correctly identified only 3% of the replacement clutches produced by geolocator‐carrying individuals and designated as first clutches a number of nests that were actually replacement clutches. Additionally, on the basis of the observational study, the repeatability of lay date was 0.24 (95% CI 0.17–0.31), whereas it was 0.54 (95% CI 0.28–0.75) using geolocator‐carrying individuals. We use examples from our own and other godwit studies to illustrate how the biases in our observational study discovered here may have affected the outcome of demographic estimates, individual‐level comparisons, and the design, implementation and evaluation of conservation practices. These examples emphasize the importance of improving and validating field methodologies and show how the addition of new tools can be transformational.

中文翻译：

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地理定位器可以更好地测量黑尾鹬的时间和重新筑巢，并揭示传统观测方法的偏差

长期人口研究可以确定人口动态随时间的变化。然而，为了得出有意义的结论，这些研究依赖于对个体特征和种群特征的准确测量。在这里，我们评估了用于测量单独标记的黑尾金雀花（Limosa limosa limosa）生殖特征的观察方法的准确性。通过将传统方法的估计值与从光级地理定位器获得的数据进行比较，我们提供了对重新筑巢的可能性和第一次离合器产卵日期的可重复性的准确估计。从 2012 年到 2018 年，我们使用记录在 68 只个体神仙携带的光级地理定位器上的阴影时期来记录它们的筑巢行为。然后，我们将这些估计值与我们的长期观察研究同时获得的估计值进行了比较。我们发现，在重新捕获的携带地理定位器的神仙中，所有鸟类在第一次离合器失败后都会重新筑巢，无论巢穴丢失的日期或已经孵化的天数。我们还发现，在第一次更换失败后，有 43% 的这些傻瓜会铺设第二个更换离合器，而在第一个离合器孵化后，21% 的这些傻瓜重新筑巢。然而，观察性研究仅正确识别了携带地理定位仪的个人生产的替换离合器的 3%，并将许多实际上是替换离合器的巢穴指定为第一离合器。此外，根据观察性研究，产蛋日期的可重复性为 0.24（95% CI 0.17-0.31），而它为 0.54（95% CI 0.28-0。75) 使用携带地理定位器的个人。我们使用来自我们自己和其他 Godwit 研究的例子来说明我们在此处发现的观察性研究中的偏差可能如何影响人口估计的结果、个人层面的比较以及保护实践的设计、实施和评估。这些示例强调了改进和验证现场方法的重要性，并展示了添加新工具如何能够带来变革。