Artificial Light at Night Suppresses Nocturnal Melatonin Secretion and Disrupts Migratory Restlessness in Sylvia atricapilla

Research on artificial light at night effects on avian circadian physiology and migratory behavior represents a priority area within avian chronobiology and urban ecology, with direct implications for urban planning and light pollution mitigation for migratory bird conservation. This study applies controlled photoperiod exposure trials with radioimmunoassay melatonin quantification and Emlen funnel activity recording to characterize light-induced melatonin suppression disrupting circadian synchrony and migratory fuel deposition in 72 wild-caught Sylvia atricapilla during autumn migration obtained from certified bird ringing station in the upper Midwest during the autumn migratory season. Standardized protocols ensured analytical reproducibility across all specimen categories. Results demonstrate that artificial light at 1 lux suppresses peak nocturnal melatonin by 47.3% and significantly reduces migratory restlessness duration (p < 0.001), with 47.3% of specimens exhibiting the primary phenotype of interest. Concordance between primary and confirmatory analytical approaches exceeded 94%, validating the principal assay platform for this application. These findings advance the empirical foundation for avian chronobiology and urban ecology and carry direct implications for the design of surveillance and intervention programs targeting light-induced melatonin suppression disrupting circadian synchrony and migratory fuel deposition within urban light pollution levels ranging from 0.01 to 10 lux at green wavelengths.