Data from: Urban links to molt schedule, body condition, and carotenoid-based coloration in the house finch (Haemorhous mexicanus)

Animals in urban environments are exposed to novel conditions, such as
habitat and dietary alterations, and night-time light pollution, that can
shift the timing and expression of life-history traits. Birds are popular
urban-ecological study subjects, and in these feathered animals regular
plumage molt is a critical process for maintenance of feather quality and
their associated functions (e.g., thermoregulation, aerodynamics, and
communicative coloration). We hypothesized that environmental changes
associated with urbanization might affect the timing and progression of
molt. As molt is energetically and nutritionally costly, we also tested
whether putative urban-rural molt differences might be explained by
indirect effects of urban environments on aspects of health (i.e. body
condition, sexually selected plumage color). We tracked body molt
intensity during molt onset, peak, and completion in both sexes of urban
and rural house finches (Haemorhous mexicanus), and related this to body
condition and sexually selected carotenoid-based plumage coloration. We
found that urban birds began molting earlier, peaked at a lower molt
intensity, and ended molt later than rural conspecifics. We also find that
both body condition and plumage hue in males explain variation in body
molt intensity differently for urban and rural populations at various
points during the molting period. Overall, we demonstrate that songbird
molt patterns and the development of carotenoid-based sexual ornaments can
be altered in urban environments, and that rapid urbanization may have
broader implications for molt dynamics, annual life-history traits, and
sexual selection.