Nests, eggs, and nestlings of Spix’s Warbling-Antbird ( Hypocnemis striata ) in Anapu, Pará, Brazil

We describe nests, eggs, and nestlings of Spix’s Warbling-Antbird ( Hypocnemis striata ) from terra firme dense forest in the municipality of Anapu, state of Pará. We found two nests in April 2016 with a basket-shaped structure, attached to the horizontal fork by thin branches, made with a mixture of vines and dry leaves. Nests and eggs follow the same pattern observed for other species in the genus Hypocnemis . Nests’ dimensions were as follows: external height 112.5 mm (nest 1) and 95.4 mm (nest 2); outside diameter 79 mm (1) and 61.4 mm (2); internal diameter 42.4 mm (1) and 32.7 mm (2); internal depth 70 mm (1) and 62 mm (2); and height in relation to the ground 60 cm (1) and 145 cm (2). The eggs are rosy with reddish-brown spots scattered all over it, with greater concentration in the terminal portion of the wider pole. During field observations and recording hours (196 min) in one nest, only the male was observed taking care of the nestlings. Although we only performed these observations for a short period, this behavior apparently differs from the pattern usually observed for other Thamnophilidae, in which both sexes engage in parental care; nevertheless, this preliminary result is not conclusive. Some aspects of the reproductive biology of the species, such as incubation period and nestling development, could not be obtained and should be subject of further investigation.