The “dawn chorus” and incubation in the coot (Fulica atra L.)

Summary It has been proposed that both acoustic and non-acoustic factors could explain the dawn peak of territorial advertisement in birds. The coot is a territorial waterbird which does not use vocal advertisement either to attract mates or defend territory boundaries. In spite of the absence of acoustic factors affecting the time budgeting of advertisement, this species shows a dawn peak of display and aggressive behaviours. This trend occurs both in the presence and absence of non-territorial prospecting birds, but the trends are quantitatively different in these two cases (Fig. 1). Males participate in display and fighting more often than females, probably because of their greater size and effectiveness in defence. This asymmetry in defence abilities governs the time budgeting of incubation, the male tending to take time off the nest when territorial defence is most necessary (Fig. 2).