Behavioral Ecology and Sociobiology ( IF 1.9 ) Pub Date : 2022-04-27 , DOI: 10.1007/s00265-022-03168-8 H. M. Scharf 1 , M. E. Hauber 1, 2 , K. H. Stenstrom 1, 3 , W. M. Schelsky 1, 2
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Abstract
Transitions between life history stages are fitness-limiting events that depend on environmental and individual characteristics. For altricial birds, fledging from the nest is a critical shift in development with direct impacts on survival, yet it remains one of the most understudied components of avian ontogeny. Even less is known about how brood parasitism affects the fledging process in host nestlings. The prothonotary warbler (Protonotaria citrea) is a host of the obligate brood parasitic brown-headed cowbird (Molothrus ater). We tested whether the presence of parasitic nestlings negatively alters host fledging by experimentally parasitizing nests with a cowbird (heterospecific parasite) or a warbler (conspecific parasite) egg, comparing them to non-manipulated control nests, and monitoring them using radio-frequency identification (RFID) systems. As expected, in heterospecifically parasitized nests, warblers were smaller, fledged at older ages, and had greater overall fledging latency compared to conspecifically parasitized nests. There was no such impact of conspecific parasitism relative to controls. Warbler nestling size predicted the age and order of fledging, with larger nestlings fledging earlier. Nestlings fledging at earlier ages fledged later during daytime hours. Cowbirds and last-fledged, smaller warbler chicks spent the most time in the nest entrance before fledging. Finally, although male warbler nestlings were larger than females, there were no sex effects or effects of extra-pair status on fledging. Our study shows that while conspecific parasitism has no detectable effect on host nestmates, heterospecific parasitism impacts host size and fledging phenology, which may influence post-fledging survival of parasitized broods.
Significance statement
In many species, juveniles undergo dramatic transitions in lifestyle as they age and become independent. For most birds, fledging from the nest is an important developmental shift, potentially impacted by their previous growth and early social experiences. One aspect that may affect fledging is brood parasitism, whereby birds lay their eggs into the nests of other birds who care for the unrelated young. Here, we determined experimentally if brood parasitism affects fledging of the prothonotary warbler, a species that always accepts eggs of the larger, obligate brood parasitic brown-headed cowbird. Our results show that while same-species parasitism has no statistical effect on the fledging of host warblers, cowbird parasitism causes delayed fledging in hosts, revealing a previously unappreciated, additional cost of brood parasitism upon host nestlings.
中文翻译：
我应该留下还是应该离开：鸟类寄生对宿主羽翼未丰的影响
摘要
生活史阶段之间的过渡是取决于环境和个人特征的健身限制事件。对于晚熟鸟类来说，离开巢穴是发育过程中的一个关键转变，对生存有直接影响，但它仍然是鸟类个体发育中研究最少的组成部分之一。对育雏寄生如何影响寄主雏鸟的发育过程知之甚少。原叶莺 (Protonotaria citrea ) 是专性育雏寄生棕头牛鸟 ( Molothrus ater）。我们通过用牛鸟（异种寄生虫）或莺（同种寄生虫）卵对巢穴进行实验性寄生，将它们与未经处理的对照巢穴进行比较，并使用射频识别对其进行监测，从而测试了寄生雏鸟的存在是否会对宿主的发育产生负面影响。 RFID）系统。正如预期的那样，在异种寄生的巢穴中，莺更小，在较老的年龄成熟，并且与特定寄生的巢穴相比具有更大的整体羽化潜伏期。相对于对照，同种寄生没有这种影响。莺雏鸟的大小预测了雏鸟的年龄和顺序，较大的雏鸟雏鸟更早。早期羽化的雏鸟在白天羽化较晚。牛鸟和最后的羽翼，较小的莺雏鸟在羽化前在巢口待的时间最多。最后，虽然雄性莺雏鸟比雌性大，但对雏鸟没有性别影响或额外配对地位的影响。我们的研究表明，虽然同种寄生对宿主巢穴没有可检测到的影响，但异种寄生会影响宿主大小和羽化物候，这可能会影响寄生幼体的羽化后存活。
意义陈述
在许多物种中，随着年龄的增长和独立，青少年的生活方式会发生戏剧性的转变。对于大多数鸟类来说，离开巢穴是一个重要的发育转变，可能会受到它们之前的成长和早期社会经历的影响。可能影响羽翼的一个方面是育雏寄生，鸟类将卵产入其他照顾无关幼鸟的鸟类的巢穴中。在这里，我们通过实验确定了育雏寄生是否会影响原发莺的羽化，这种莺总是接受较大的专性育雏寄生棕头牛鸟的卵。我们的研究结果表明，虽然同种寄生对寄主莺的羽化没有统计上的影响，但牛鸟寄生会导致宿主的羽化延迟，揭示了一个以前未被重视的，
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