Accurately measuring nest survival is challenging because nests must be discovered to be monitored, but nests are typically not found on the first day of the nesting interval. Studies of nest survival therefore often monitor a sample that overrepresents older nests. To account for this sampling bias, a daily survival rate (DSR) is estimated and then used to calculate nest survival to the end of the interval. However, estimates of DSR (and thus nest survival) can still be biased if DSR changes with nest age and nests are not found at age 0. Including nest age as a covariate of DSR and carefully considering the method of estimating nest survival can prevent such biases, but many published studies have not fully accounted for changes in DSR with nest age. I used a simulation study to quantify biases in estimates of nest survival resulting from changes in DSR with nest age under a variety of scenarios. I tested four methods of estimating nest survival from the simulated datasets and evaluated the bias and variance of each estimate. Nest survival estimates were often strongly biased when DSR varied with age but DSR was assumed to be constant, as well as when the model included age as a covariate but calculated nest survival from DSR at the mean monitored nest age (the method typically used in previous studies). In contrast, biases were usually avoided when nest survival was calculated as the product of age-specific estimates of DSR across the full nesting interval. However, the unbiased estimates often showed large variance, especially when few nests were found at young ages. Future field studies can maximize the accuracy and precision of nest survival estimates by aiming to find nests at young ages, including age as a covariate in the DSR model, and calculating nest survival as the product of age-specific estimates of DSR when DSR changes with nest age.

中文翻译：

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在量化巢穴存活率时，充分考虑巢龄可减少偏差

准确测量巢穴存活率具有挑战性，因为必须发现巢穴才能进行监测，但通常在筑巢间隔的第一天找不到巢穴。因此，关于巢穴生存的研究经常监测一个代表较老巢穴的样本。为了解释这种抽样偏差，估计了每日存活率 (DSR)，然后用于计算到间隔结束的巢存活率。然而，如果 DSR 随巢龄变化而巢龄为 0 时未发现巢，则 DSR（以及巢存活率）的估计仍然存在偏差。将巢龄作为 DSR 的协变量并仔细考虑估计巢生存的方法可以防止这种情况发生偏差，但许多已发表的研究并未完全解释 DSR 随巢龄的变化。我使用模拟研究来量化在各种情况下 DSR 随巢龄变化而导致的巢生存估计偏差。我测试了四种从模拟数据集中估计巢生存的方法，并评估了每个估计的偏差和方差。当 DSR 随年龄而变化但 DSR 被假定为常数时，以及当模型将年龄作为协变量但在平均监测巢龄时从 DSR 计算巢穴存活率时，巢穴存活率估计通常存在很大偏差（以前的方法通常使用学习）。相比之下，当巢生存被计算为整个巢间隔中 DSR 的特定年龄估计值的乘积时，通常可以避免偏差。然而，无偏估计通常显示出很大的差异，尤其是在年轻时发现的巢穴很少时。