Paillisson Jean-Marc, Chambon Rémi
University of Rennes, CNRS, ECOBIO [(Ecosystèmes, biodiversité, évolution)] - UMR 6553 Rennes France.
Ecol Evol. 2021 Nov 4;11(22):15585-15600. doi: 10.1002/ece3.8162. eCollection 2021 Nov.
Nest building can represent an energetically costly activity for a variety of animal taxa. Besides, the determinants of within-species variation in the design of nests, notably with respect to natural and sexual selection, are still insufficiently documented. Based on an observational study, we examined the influence of nesting conditions (nesting-support quality, colony, laying date, and year) on male-built nest volume and also its potential role as a postmating sexually selected display in the whiskered tern . This tern species is a monogamous colonial bird with obligate biparental care breeding on aquatic vegetation. Hence, large nesting platforms are expected to be a selective advantage because they would better withstand adverse environmental conditions and provide a secure structure for eggs. Nest size may also serve as a postmating sexual trait, and variation in egg production would be positively associated with nest size. We found that nest volume was adjusted to different environmental cues. A positive relationship was found between nest volume and nesting-support quality, indicating that the leaf density of white waterlily is essential for nest stability. Variation in nest volume was not correlated to colony size but varied among colonies and years. Male-built nest volume was also positively associated with mean egg volume per clutch but not with clutch size. The fitness consequences of building a large nest are yet to be studied, and additional investigations are recommended to better understand whether the activity of males early during breeding season (e.g., nest building and courtship feeding performance) really serves as postmating sexually selected signals.
筑巢对于多种动物类群而言可能是一项消耗大量能量的活动。此外，关于巢设计的种内变异的决定因素，尤其是在自然选择和性选择方面，仍缺乏充分的记录。基于一项观察性研究，我们考察了筑巢条件（筑巢支撑质量、群落、产卵日期和年份）对雄性筑巢体积的影响，以及它在须浮鸥中作为交配后性选择展示的潜在作用。这种浮鸥是一种实行一夫一妻制的群居鸟类，在水生植物上进行双亲育雏。因此，大型筑巢平台预计具有选择优势，因为它们能更好地抵御不利的环境条件，并为卵提供一个安全的结构。巢的大小也可能作为交配后的性特征，产卵量的变化可能与巢的大小呈正相关。我们发现巢的体积会根据不同的环境线索进行调整。巢体积与筑巢支撑质量之间呈正相关，这表明白睡莲的叶片密度对巢的稳定性至关重要。巢体积的变异与群落大小无关，但在不同群落和年份之间存在差异。雄性筑巢体积也与每窝卵的平均体积呈正相关，但与窝卵数无关。建造大型巢的适应性后果还有待研究，建议进行更多调查，以更好地了解繁殖季节早期雄性的活动（如筑巢和求偶喂食表现）是否真的作为交配后的性选择信号。
