ABSTRACT The mass of a bird's egg is a critical attribute of the species' life history and represents a fundamental component of reproductive effort. Indeed, the tradeoff between the number of eggs in a clutch and clutch mass lies at the heart of understanding how environmental attributes such as nest predation or adult mortality influence reproductive investment. However, egg masses have not been reported for the majority of avian species. We capitalized on the strong allometric relationship between avian body mass and egg mass to produce egg mass estimates for over 5,500 species previously lacking such information. These estimates are accompanied by measures of the robustness of the regressions used to produce them (e.g., sample size, root mean square error [RMSE] of estimation, coefficient of determination, and degree of extrapolation), thus allowing independent evaluation of the suitability of any estimate to address a particular research question relating to avian life history. Most estimates (∼5,000) were based on family-level egg mass–body mass regressions, with the remainder derived from other relationships such as ordinal regressions. We compared estimating regressions based on adult vs. female body masses and, after finding little difference between the 2, based our final estimates on adult masses as those were more numerous in the literature. What small differences between adult- and female-based regressions that did occur were not related to sexual size dimorphism across families. These new estimates, coupled with ∼5,000 egg masses reported in the literature, provide a foundation of over 10,000 species for wider investigations assessing variation in reproductive effort in birds over a broad array of ecological and evolutionary contexts. LAY SUMMARY The mass of a bird's egg is a critical attribute of the species' life history but has not been reported for the majority of avian species. We capitalized on the strong statistical relationship between egg mass and avian body mass (known for almost all bird species) to produce new egg mass estimates for over 5,500 species previously lacking such information. Most estimates (∼5,000) were based on family level regressions of egg mass on body mass, with the remainder derived from other relationships such as order regressions. We found little difference between egg mass relationships calculated from adult vs. female-only body masses and based our final estimates on adult masses as those were more numerous in the literature. These new estimates, coupled with ∼5,000 egg masses reported in the literature, provide a foundation of over 10,000 species for wider investigations examiniing variation in reproductive effort in birds over a broad array of ecological and evolutionary contexts.

中文翻译：

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估计鸟类的蛋质量-体重关系

摘要 鸟蛋的质量是该物种生活史的关键属性，也是繁殖努力的基本组成部分。事实上，一窝卵数量和一窝卵数量之间的权衡是理解巢捕食或成虫死亡率等环境属性如何影响繁殖投资的核心。然而，尚未报告大多数鸟类物种的卵块。我们利用鸟类体重和卵质量之间的强异速生长关系，对以前缺乏此类信息的 5,500 多种物种进行卵质量估计。这些估计伴随着用于产生它们的回归稳健性的度量（例如，样本大小、估计的均方根误差 [RMSE]、确定系数和外推程度），从而允许对任何估计的适用性进行独立评估，以解决与鸟类生活史相关的特定研究问题。大多数估计值（~5,000）基于家庭级鸡蛋质量-体重回归，其余来自其他关系，如序数回归。我们比较了基于成人和女性体重的估计回归，在发现两者之间几乎没有差异之后，我们基于成人体重的最终估计，因为文献中的数量更多。确实发生的基于成人和基于女性的回归之间的微小差异与跨家庭的性别大小二态性无关。这些新的估计，再加上文献中报道的约 5,000 个卵块，提供了超过 10 个的基础，000 种，用于更广泛的调查，以评估鸟类在广泛的生态和进化背景下繁殖努力的变化。家禽总结 鸟蛋的质量是该物种生活史的关键属性，但尚未报道大多数鸟类物种。我们利用鸡蛋质量和鸟类体重（几乎所有鸟类都知道）之间的强统计关系，对以前缺乏此类信息的 5,500 多种物种进行新的鸡蛋质量估计。大多数估计（~5,000）基于鸡蛋质量对体重的家庭级回归，其余来自其他关系，如顺序回归。我们发现从成人和成年计算的卵子质量关系之间几乎没有差异 仅限女性的体重，并基于我们对成年体重的最终估计，因为文献中的数量更多。这些新的估计值加上文献中报道的约 5,000 个卵质量，为更广泛的调查提供了超过 10,000 个物种的基础，以检查在广泛的生态和进化背景下鸟类繁殖努力的变化。