Abstract The adult sex ratio (ASR) is a crucial component of the ecological and evolutionary forces shaping the dynamics of a population. Although in many declining populations ASRs have been reported to be skewed, empirical studies exploring the demographic factors shaping ASRs are still rare. In this study of the socially monogamous and sexually dimorphic Black-tailed Godwit (Limosa limosa limosa), we aim to evaluate the sex ratio of chicks at hatch and the subsequent sex-specific survival differences occurring over 3 subsequent life stages. We found that, at hatch, the sex ratio did not deviate from parity. However, the survival of pre-fledged females was 15–30% lower than that of males and the sex bias in survival was higher in low-quality habitat. Additionally, survival of adult females was almost 5% lower than that of adult males. Because survival rates of males and females did not differ during other life-history stages, the ASR in the population was biased toward males. Because females are larger than males, food limitations during development or sex-specific differences in the duration of development may explain the lower survival of female chicks. Differences among adults are less obvious and suggest previously unknown sex-related selection pressures. Irrespective of the underlying causes, by reducing the available number of females in this socially monogamous species, a male-biased ASR is likely to contribute to the ongoing decline of the Dutch godwit population.

中文翻译：

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出生栖息地和特定性别的存活率导致男性偏向的成人性别比例

摘要 成人性别比 (ASR) 是塑造种群动态的生态和进化力量的重要组成部分。尽管据报道，在许多下降的人群中，ASR 存在偏差，但探索影响 ASR 的人口因素的实证研究仍然很少见。在这项对社会一夫一妻制和性别二态的黑尾鸬鹚 (Limosa limosa limosa) 的研究中，我们的目标是评估孵化时雏鸡的性别比例以及随后 3 个后续生命阶段发生的性别特异性生存差异。我们发现，在孵化时，性别比例没有偏离胎次。然而，未成熟的雌性的存活率比雄性低 15-30%，并且在低质量栖息地中生存的性别偏见更高。此外，成年女性的存活率几乎比成年男性低 5%。由于雄性和雌性的存活率在其他生活史阶段没有差异，因此人群中的 ASR 偏向于雄性。由于雌性比雄性大，发育过程中的食物限制或发育期间的性别特异性差异可能是雌性雏鸡存活率较低的原因。成年人之间的差异不太明显，这表明存在以前未知的与性别相关的选择压力。不管根本原因是什么，通过减少这种社会一夫一妻制物种中可用的雌性数量，偏向雄性的 ASR 可能会导致荷兰金雀种群的持续下降。发育期间的食物限制或发育期间的性别特异性差异可能是雌性雏鸡存活率较低的原因。成年人之间的差异不太明显，表明存在以前未知的与性别相关的选择压力。不管根本原因是什么，通过减少这种社会一夫一妻制物种中可用的雌性数量，偏向雄性的 ASR 可能会导致荷兰金雀种群的持续下降。发育过程中的食物限制或发育持续时间的性别差异可能是雌性雏鸡存活率较低的原因。成年人之间的差异不太明显，这表明存在以前未知的与性别相关的选择压力。不管根本原因是什么，通过减少这种社会一夫一妻制物种中可用的雌性数量，偏向雄性的 ASR 可能会导致荷兰金雀种群的持续下降。