Data from: Early exposure to a bacterial endotoxin advances the onset of moult in the European starling

In animals, events occurring early in life can have profound effects on subsequent life-history events. Early developmental stresses often produce negative long-lasting impacts, although positive effects of mild stressors have also been documented. Most studies of birds have investigated the effects of events occurring at early developmental stages on the timing of migration or reproduction, but little is known on the long-term effects of these early events on moulting and plumage quality. We exposed European starling (Sturnus vulgaris) nestlings to an immune challenge to assess the effects of a developmental stress on the timing of the first (post-juvenile) and second (post-breeding) complete annual moult, the length of the flight feathers, and the length and colouration of ornamental throat feathers. The nestlings were transferred to indoor aviaries before fledgling and kept in captivity until the end of post-breeding moult. Individuals treated with Escherichia coli lypopolysaccharide (LPS) started both moult cyclesing earlier compared to control siblings in either years. Moult duration was unaffected by the immune challenge, but an advanced moult onset resulted in a longer moult duration. Moreover, female (but not male) throat feather colouration of LPS-injected -exposed individuals showed a reduced UV chroma. We argue that an early activation of the immune system caused by LPS may allow nestlings to better cope with post-fledging stresses and possibly lead to improved body condition and earlier moult onset. The effect of early LPS exposure was remarkably persistent, as it was still visible more than one year after the treatment, and highlighted the importance of early developmental stresses in shaping subsequent major life-history traits, including the timing of moult in birds.在动物中，生命早期发生的事件会对后续的生活史事件产生深远影响。早期发育压力通常会带来持久的负面影响，但轻度应激源的积极效应也已有文献记载。针对鸟类的多数研究已探讨了早期发育阶段事件对迁徙或繁殖时机的影响，但关于此类早期事件对换羽和羽毛质量的长期影响，目前仍知之甚少。我们通过免疫激发（immune challenge）处理欧椋鸟（Sturnus vulgaris）幼雏，以评估发育压力对首次（幼鸟换羽后）和第二次（繁殖后）完整年度换羽的时机、飞羽长度，以及装饰性喉羽的长度与色彩的影响。幼雏在离巢前被转移至室内鸟舍，并圈养至繁殖后换羽结束。注射大肠杆菌脂多糖（LPS）的个体，其两次换羽周期的启动时间均早于同窝对照幼鸟，且该现象在两年实验中均存在。换羽时长不受免疫激发的影响，但换羽启动越早，换羽持续时间越长。此外，注射LPS处理组的雌性（而非雄性）喉羽色彩的紫外色度显著降低。我们认为，LPS引发的早期免疫系统激活，可帮助幼雏更好地应对离巢后的应激压力，或可改善其身体状况并促使换羽提前启动。早期LPS暴露的影响异常持久，在处理一年多后仍可观测到，这凸显了早期发育压力在塑造鸟类后续重要生活史特征（包括换羽时机）中的关键作用。