Is dawn singing related to paternity insurance? The case of the collared flycatcher

Abstract

Dawn singing activity of eight paired males of the collared flycatcher, Ficedula albicollis, was studied during the breeding season of 1988 on the island of Gotland in the Baltic. The main aim was to test whether the intensity of dawn song was associated with the period of female fertility. In general, paired males started to sing 1·5 h before sunrise, and the dawn song lasted less than 1 h. The duration of the dawn song seemed to depend on whether the male had contact with his mate, since each male stopped singing when his female appeared close to the nestbox. Neither variation in duration nor variation in song rate was associated with the period of female fertility (measured as days from egg laying), but both were related to date. Hence, the idea that dawn song functions to protect paternity was not supported. Dawn singing ceased when (1) unpaired males stopped singing, (2) no new breeding attempts commenced, and (3) none of the widowed (due to predation) males started to sing. It is suggested that predation on females in the nest, in combination with the arrival of new females and with the low costs and risks of singing under poor light conditions, make dawn singing advantageous, since it may maximize the probability of a male remating quickly if his female has disappeared.