Abstract

In many species, both males and females possess sexual signals, but most research focuses on understanding signal expression in males. Females are often assumed to possess signals as a non-functional by-product of selection on males, but increasing evidence demonstrates functional explanations for variation in female signals. Theory suggests that—for many bird species—differences in long-term fitness associated with female signaling are more likely to be driven by variation in offspring quality than quantity, but research paradigms developed for studying male signals have primarily focused on counting offspring produced. Here, we tested the hypothesis that female ornamentation reliably signals the ability to incubate effectively. We used temperature loggers placed in the nest of common yellowthroat warblers (Geothlypis trichas) to record incubation behavior across multiple breeding attempts. Incubation bout length and the onset of daily activity were highly variable between females, but repeatable within females across multiple nesting attempts. Females with longer bouts and later onset of activity had higher hatching success. Wing length and plumage coloration were not related to incubation length or onset of activity, but were correlated with the total percentage of time spent on the nest each day. However, there was only a trend for repeatability in percentage of time spent on the nest and this measure was not correlated with any metrics of offspring quality or hatching success that we recorded. Therefore, we did not find any single aspect of incubation behavior that was (i) consistent, (ii) related to nestling quality or success, and (iii) signaled by ornamentation. Our results demonstrate the importance of variation in incubation behavior, but also suggest that ornaments are of limited utility as a signal of incubation ability in this species. Nevertheless, our study highlights the need to explore alternative fitness proxies in order to understand variation in female ornamentation.

Significance statement

Choosing a high-quality mate is an important determinant of reproductive success and animals often attend to elaborate ornaments as signals of quality during mate choice. In many species, both males and females have ornaments, but most research has focused on male signals and female mate choice. We found that female incubation behavior is associated with both plumage ornaments and hatching success, but there was no single signal that provided reliable information about the aspects of incubation behavior that were related to reproductive success. Our findings suggest that understanding female ornamentation may depend on considering the specific ways that females contribute to offspring survival.

中文翻译：

---

野鸟中的雌性装饰，孵化行为和繁殖成功

摘要

在许多物种中，雄性和雌性都具有性信号，但是大多数研究着重于理解雄性中的信号表达。通常认为雌性具有信号，这是雄性选择的非功能性副产物，但是越来越多的证据证明了雌性信号变异的功能性解释。理论表明-对于许多鸟类而言，与雌性信号相关的长期适应性差异更可能是由后代质量的变化而非数量引起的，但是研究雄性信号的研究范例主要集中在对产生的后代进行计数。在这里，我们检验了女性装饰物可靠地发出有效孵化能力的假说。我们使用温度记录器放置在常见的黄喉鸣鸟巢中（th）以记录多次育种尝试中的孵化行为。雌性之间的孵化期长度和日常活动的开始是高度可变的，但是在多次筑巢尝试中，雌性内的重复性可重复。发作时间较长且活动开始较晚的雌性孵化成功率较高。翅膀的长度和羽毛的颜色与孵化的长度或活动的开始无关，但与每天在巢上花费的总时间百分比有关。但是，在巢上花费的时间百分比只有可重复性的趋势，并且该度量与我们记录的任何后代质量或孵化成功率均不相关。因此，我们没有发现任何与（i）一致，（ii）与雏鸟的质量或成功有关，以及（iii）装饰有关的孵化行为的任何方面。我们的结果证明了孵化行为变化的重要性，但也表明装饰品作为该物种孵化能力的信号的用途有限。然而，我们的研究强调需要探索替代的健身代理，以了解女性装饰的变化。

重要性声明

选择高品质的配偶是繁殖成功的重要决定因素，动物在配偶选择过程中经常会参加精心制作的装饰品，以此作为高品质的信号。在许多物种中，雄性和雌性都有装饰物，但是大多数研究都集中在雄性信号和雌性伴侣的选择上。我们发现雌性的孵化行为与羽毛装饰和孵化成功有关，但是没有一个信号可以提供与繁殖成功有关的孵化行为方面的可靠信息。我们的发现表明，了解雌性装饰可能取决于考虑雌性对后代存活的特定方式。