<b>Asian koels do not lay eggs matching the host eggs’ phenotype: an experimental test of the egg matching hypothesis</b>

Fieldwork was conducted on the Jahangirnagar University campus (23˚52´ N, 90˚16´ E), Bangladesh. The study area is a heterogenous landscape (approximately 280 ha) and includes woodlands, grasslands, wetlands, cultivated lands and human settlements (Nahid et al., 2020). Multiple cuckoo species differing in size from small to large coexist and breed sympatrically in the study area (Nahid et al., 2016a, b).<b>Study species</b>The koel is a generalist, non-evictor brood parasite distributed throughout Asia (Ali and Ripley, 1981; Payne, 2005; Erritzøe et al., 2012). It is the most common resident among the cuckoos in the study area. A total of 16 passerine species from different areas have been recorded as hosts of the koel (Mann, 2017). In our study area, the koel regularly parasitizes nests of house crows (<i>Corvus splendens</i>), mynas and long-tailed shrikes (<i>Lanius schach</i>) (Begum et al., 2011; Nahid et al., 2020, 2021). The koel clutch size is usually 2-3, but up to 13 koel eggs have been recorded in one host nest (Payne, 2005; Erritzøe et al., 2012; Nahid et al., 2021).The myna is widely distributed in south and south-east Asia and is one of the most exploited hosts by the koel in our study area with the parasitism rate between 31.2% and 33.6% (BirdLife International, 2017; Craig et al., 2019; Nahid et al., 2021). Additionally, a recent study found that 21.2% (n=99 nests) of mynas that nested in nest boxes were parasitised in our study area (Nahid et al., 2024). The myna builds nests most often in cavities, close to human habitation, as well as in natural areas (Lamba, 1963; Ali and Ripley, 1981; Begum et al., 2011b). It breeds from March to August in Bangladesh, but it can breed all through the year depending on the area (Begum et al., 2011a, Nahid et al., 2020). The clutch size is usually 4-5 eggs (Nahid et al., 2021).In this study, we demonstrate that Asian koels lay randomly, and do not differentiate between active common myna nests or dummy nests with domestic quail (<i>Coturnix coturnix</i>) eggs or dummy nests without quail eggs. This lack of discrimination between these different experimental groups, strongly suggests that Asian koels were not matching host eggs in this experiment. In addition, common myna eggs from parasitized nests did not appear more similar to Asian koel eggs compared to common myna eggs from unparasitized nests. Together, these findings present convincing results showing that, rather than attempting to lay eggs in nests that best match their own in appearance, Asian koels lay eggs indiscriminately in any potential active common myna nest.野外工作于孟加拉国贾汉吉尔纳加尔大学校园（23°52′N，90°16′E）开展。本研究区域为面积约280公顷的异质景观，涵盖林地、草原、湿地、耕地与人类聚居区（Nahid等，2020）。该区域共存有体型从小型至大型的多种杜鹃类群，并存在同域繁殖现象（Nahid等，2016a、b）。 **研究物种** 亚洲噪鹃（Asian koel）为广食性、非逐出型巢寄生鸟类，广泛分布于亚洲（Ali与Ripley，1981；Payne，2005；Erritzøe等，2012），是本研究区域内最为常见的留居杜鹃类群。目前已有16个雀形目类群被记录为亚洲噪鹃的宿主（Mann，2017）。在本研究区域内，亚洲噪鹃常寄居于家鸦（*Corvus splendens*）、家八哥以及长尾伯劳（*Lanius schach*）的巢中（Begum等，2011；Nahid等，2020、2021）。亚洲噪鹃的窝卵数通常为2~3枚，但曾有记录显示单个宿主巢内最多可发现13枚亚洲噪鹃卵（Payne，2005；Erritzøe等，2012；Nahid等，2021）。 家八哥（Common myna）广泛分布于南亚与东南亚地区，是本研究区域内亚洲噪鹃最主要的宿主类群之一，其巢寄生率介于31.2%~33.6%之间（BirdLife International，2017；Craig等，2019；Nahid等，2021）。此外，近期一项研究发现，本研究区域内21.2%（n=99个巢）的箱式巢家八哥个体被亚洲噪鹃寄生（Nahid等，2024）。家八哥多在贴近人类聚居区的树洞或自然生境中筑巢（Lamba，1963；Ali与Ripley，1981；Begum等，2011b）。在孟加拉国，其繁殖期为3月至8月，但在不同区域全年均可繁殖（Begum等，2011a；Nahid等，2020）。家八哥的窝卵数通常为4~5枚（Nahid等，2021）。 本研究证实，亚洲噪鹃的产卵行为具有随机性，并不会区分活跃的家八哥巢、放置有普通鹌鹑（*Coturnix coturnix*）卵的人工假巢，以及未放置鹌鹑卵的人工假巢。这类对不同实验组无区分度的行为，强烈表明本实验中亚洲噪鹃并未匹配宿主卵的外观特征。此外，相较于未被寄生巢中的家八哥卵，被寄生巢中的家八哥卵与亚洲噪鹃卵的外观相似度并未更高。综上，本研究结果清晰表明：亚洲噪鹃并不会选择外观与自身卵最为匹配的巢进行产卵，而是会随机在任意潜在的活跃家八哥巢中产卵。