Notes on the Incubation, Brooding, and Provisioning Behavior of Chuck-will's-widows

摘要

Because of their cryptic plumage and nocturnal habits, little is known about the breeding behavior of Chuck-will's-widows (Antrostomus caroli-nensis). Using temperature loggers and video-recordings, we quantified the incubation, brooding, and provisioning behavior of male and female Chuck-will's-widows in Adams County, Ohio, in 2011 and 2012. We located six nests, all 2-egg clutches laid on the ground. Four nests were successful, one was depredated, and one was abandoned. We quantified incubation behavior at all nests (mean = 5.5 days; range = 0.4-12.9 days). Adult Chuck-will's-widows incubated an average of 89.2% of the time, with females observed incubating more than males. Most incubation off-bouts (n = 104) occurred at dawn (0400-0659; n = 45) and dusk (1900-2200; n = 48) and averaged 35 mins in duration. After hatching, the mean duration of brooding bouts was 20 mins (age of young = 1-7 days). Both males and females provisioned young, and feeding rates were highest (P = 0.003) during the hour immediately after sunset. The timing of off-bouts during incubation and provisioning visits after hatching suggests that Chuck-will's-widows in our study foraged primarily at dawn and dusk. Previous authors have noted that nightjars are visual predators and, therefore, their foraging behavior may be constrained by light levels.