Artificial light at night amplifies seasonal relapse of haemosporidian parasites in a widespread songbird

Urban habitats can shape interactions between hosts and parasites by altering within-host processes such as resistance. Artificial light at night is common in urban environments, and chronic exposure can impair host immunity in ways that may increase infection. However, studies of causal links between this stressor, immunity, and infection dynamics are rare, particularly in migratory animals. Here, we experimentally tested how artificial light at night affects cellular immunity and intensity of infection with haemosporidian parasites across the annual cycle of migrant and resident subspecies of the dark-eyed junco (Junco hyemalis). We exposed an experimental group to light at night and compared them to control birds under nighttime darkness. Both groups were monitored as they passed through short days simulating early spring to longer days simulating the breeding season, followed by fall migration. Using generalized additive models, we show that artificial light at night increased infla...

城市生境可通过改变宿主内在过程（如抗性），塑造宿主与寄生虫之间的互作关系。夜间人工光照在城市环境中极为普遍，长期暴露会损伤宿主免疫功能，进而可能提升感染风险。然而，针对该胁迫因子、免疫与感染动态之间因果关联的研究尚少，在迁徙动物中尤为匮乏。本研究以暗眼灯草鹀（Junco hyemalis）的迁徙亚种与居留亚种为研究对象，在其年度生活周期内，通过实验探究夜间人工光照如何影响细胞免疫功能以及血孢子虫（haemosporidian parasites）的感染强度。我们将实验组暴露于夜间光照环境，并与处于夜间黑暗环境的对照组鸟类进行对比。两组鸟类均接受监测：先经历模拟早春的短日照阶段，再过渡至模拟繁殖期的长日照阶段，随后进入模拟秋季迁徙的阶段。本研究使用广义加性模型（generalized additive models）分析后发现，夜间人工光照会提升炎症反应……