Temporal structure of avian dawn chorus along a landscape anthropization gradient

AbstractContextIf an animal community can be similar from a city to its outskirts, its rhythm of activity can be modified by anthropogenic pressures. Passive acoustic monitoring techniques offer the opportunity to assess such changes in birdsong along anthropization gradients.ObjectivesDisentangling the relative influence of anthropogenic pressures, landscape composition and the composition of the bird community on the temporal structure of dawn chorus.MethodsBirdsongs were recorded in France in 36 stations located along an anthropization gradient through passive acoustic devices. The temporal structure of birdsongs was confronted to anthropogenic pressures (artificial lights and traffic noise), landscape composition indices (landscape diversity, areas covered by woodland and buildings) and characteristics of the bird community (abundance, species richness and diversity) around each station.ResultsFor a given species, birds tend to sing earlier and during shorter periods in areas densely built, submitted to high levels of artificial lights, traffic noise, and in areas hosting the lowest conspecific abundances. Highly built and lit areas lead to a community reassembly promoting late singing species and species singing for short periods. Artificial lights and traffic noise promote a higher species temporal turnover and a lower temporal nestedness of the dawn chorus at the community level.ConclusionsIn cities, birds tend to sing earlier, during shorter periods, and the different species sing in a succession rather than in a polyphony. The full bird chorus, gathering almost all the species of a community singing together in the same time seems to have disappeared from the most anthropized areas.