Urbanization shapes the relation between density and melanin-based colouration in bird communities

Growing urbanization increasingly influences ecosystems worldwide. While the effects of urban conditions within species (through either plastic or evolutionary responses) have been widely studied, their potential influences among species (through environmental filter), especially concerning their colouration, remain poorly known. Here, we investigated whether avian communities breeding inside and outside a major European city (Paris) differ with regards to melanin-based plumage colouration. Melanins are heritable pigments present in many taxa and have a series of unique properties that may allow coping with urban conditions. Using melanic-based colouration as an integrative phenotypic marker, we predicted (i) that the probability of breeding inside the city should increase with the intensity of species melanin-based colouration, (ii) that for species breeding both inside and outside the city, density should increase with the intensity of dark colouration inside the city, but not outside...