Nest and nestling development of the Sooty-capped Hermit (Phaethornis augusti) from Venezuela

Abstract

In order to improve the previous knowledge about the nest and nestling development of the Sooty-capped Hermit (Phaethornis augusti) from Venezuela, a nest was followed from February to July 2015. Details of nest structure (shape, materials, dimensions), nest usage, intervals between breeding attempts, hatch time, fledgling period, as well as nestling development data such as body mass, measures, nestling condition on hatching, pterilia development, and when eyes opened were all recorded in detail. The nest had the typical cup-shape structure that hung by a single stout cable of spiders' silk from a single iron nail 1.90 m above the floor, built with moss and spider webbing, inside a shadowy, fresh, and quiet storehouse. Despite appearing to be bulky and heavy, the nest had a mass of only 9.4 g. After four consecutive breedings by a single female, several hitherto unknown parameters were determined, including intervals between breeding attempts (10–21 days), incubation period (20 ± 0 days), fledgling period (26 ± 0 days), egg mass (0.6 ± 0 g); egg lengths (14.0 ± 0.05 mm), nestling mass at hatching (0.65 ± 0.07 g), and nestling mass at fledging (6.1 g). Breeding season of Sooty-capped Hermit was better understood: December–July, with scant records between September–November. Sooty-capped Hermit reproductive success (87.5%) was higher than that of other related species which nest in more natural conditions (16.7%). This is probably due to the breeding strategy of nesting within man-made constructions that offer protection from most natural predators.