Temporal structure of avian dawn chorus along an urbanization gradient

Abstract Disentangling the relative influence of different anthropogenic pressures, landscape composition and biotic conditions on birdsong from species to community levels is challenging. On the basis of a field survey conducted on a breeding bird community in France, we measured the influence of such factors on the timing of birdsongs along an urbanization gradient. First, we found that species can be sorted according to different time song indices, and early singing species are also those with the largest eye sizes. For a given species, birds sing earlier and during shorter period in areas densely built, submitted to high levels of artificial lights, traffic noise, and in areas hosting the lowest conspecific abundances. At the community level, urbanization, and especially highly built and lit areas, leads to a community reassembly promoting late singing species and species singing for short periods. Finally, artificial lights and traffic noise promote a higher species temporal turnover and a lower temporal nestedness of the dawn chorus at the community level: different species tend to sing in a succession rather than in a polyphony. Our results suggest that the full bird chorus, gathering almost all the species singing together in the same time has thus disappeared in the most urbanized areas.