Piersma T, Mendes L, Hennekens J, Ratiarison S, Groenewold S, Jukema J
Netherlands Institute for Sea Research, The Netherlands.
Zoology (Jena). 2001;104(1):41-8. doi: 10.1078/0944-2006-00003.
The indicator mechanism for sexual selection proposed by Hamilton and Zuk (i.e. that sexually selected ornaments signal parasite resistance) has received rather little observational support, and none in the case of long-distance migrant birds. Here we present a test by examining the association between helminth infestations and breeding plumage quality in bar-tailed godwits Limosa lapponica taymyrensis during their spring staging period in the Wadden Sea, The Netherlands. After a non-stop flight from West Africa, these shorebirds refuel in the Wadden Sea in preparation for a second flight to the central Siberian Arctic breeding grounds. Earlier studies have shown that only relatively heavy and well ornamented birds carry out a "top-up" moult during stopover, in which part of the contour feathers recently grown in West Africa are replaced by even fresher ones. Active body moult was therefore taken as the primary indicator of ornament quality. Of 78 birds collected between 1992 and 1997, 42% carried helminths, including four species of digenean trematodes (flukes), three species of cestodes (tapeworms) and an acanthocephalan (spiny-headed worm). Faecal samples examined for helminth eggs in another 92 birds in 1998 and 2000 showed similar rates of infestation. Actively moulting bar-tailed godwits were confirmed to be heavier and to show more extensive breeding plumage than non-moulting birds. In females, but not in males, active moult was associated with fewer cestodes and acanthocephalans. Also, breeding plumage and presence of cestodes were negatively associated in females. We argue that the quality of the breeding plumage reliably indicates parasite resistance in female godwits. The repeatability of plumage scores of females between years is consistent with such resistance having a heritable component. In contrast, male ornaments may demonstrate other qualities, e.g. an ability to combine adequate fuelling and flight performances with moult during the time-stress of migration.
汉密尔顿和祖克提出的性选择指标机制（即性选择的装饰物表明对寄生虫的抵抗力）得到的观测支持相当少，对于长途迁徙鸟类而言则毫无支持。在此，我们通过研究斑尾塍鹬（Limosa lapponica taymyrensis）在荷兰瓦登海春季停歇期的蠕虫感染情况与繁殖羽质量之间的关联进行了一项测试。这些滨鸟从西非不间断飞行后，在瓦登海补充能量，为再次飞往西伯利亚中部北极繁殖地做准备。早期研究表明，只有相对较重且装饰物较好的鸟类在中途停歇时会进行“补充”换羽，即把最近在西非长出的部分体羽换成更新鲜的羽毛。因此，活跃的身体换羽被视为装饰物质量的主要指标。在1992年至1997年间收集的78只鸟中，42%携带蠕虫，包括四种复殖吸虫（吸虫）、三种绦虫（绦虫）和一种棘头虫（棘头虫）。1998年和2000年对另外92只鸟的粪便样本进行蠕虫卵检测，结果显示感染率相似。经证实，正在进行活跃换羽的斑尾塍鹬比未换羽的鸟更重，繁殖羽更丰满。在雌性中，但在雄性中未发现，活跃换羽与绦虫和棘头虫数量较少有关。此外，雌性的繁殖羽与绦虫的存在呈负相关。我们认为，繁殖羽的质量可靠地表明了雌性塍鹬对寄生虫的抵抗力。雌性羽毛分数在不同年份之间的可重复性与这种抵抗力具有遗传成分是一致的。相比之下，雄性的装饰物可能展示出其他品质，例如在迁徙的时间压力下，有能力在补充能量和飞行表现的同时进行换羽。
