Expression of and choice for condition-dependent carotenoid-based color in an urbanizing context

Urban environments create a unique suite of conditions, leading to changes in animal behavior, morphology, phenology or physiology. Condition-dependent traits such as the carotenoid-based coloration offer a unique opportunity to assess the impacts of urbanization on organisms because they reflect the nutrition, health or other resource-based attributes of their bearers and they play an essential role in intra- and inter-sex interactions. To determine if and how the carotenoid-based coloration of male house finches (Haemorhous mexicanus) varies along a gradient of urbanization, we quantified the plumage coloration of more than 1200 individuals in urban, suburban, rural and desert habitats over the course of 17 months. We also examined for the first time the preference of females for male plumage coloration across the urban-rural gradient, to test if and how female preferences varied relative to the range of plumage coloration displayed by males in their local population. We found that ca...