Breeding ecology of Rufous Casiornis Casiornis rufus in south-east Brazil

Abstract

We present new reproductive information for the Rufous Casiornis Casiornis rufus, based on studies undertaken during 1991–99 and in 2018, in the municipality of Arcos, Minas Gerais, south-east Brazil. We found eight nests, all sited in cavities of dead trees or wooden fence posts, on average 62.8 cm above ground. Clutch size was usually three eggs, pale beige overlain with complex markings throughout, similar to those of the genus Myiarchus. Eggs measured on average 22.8 × 16.96 mm, mass c.3 g. Incubation lasted c.15 days, and nestlings remained in the nest 15–17 days, being fed by both adults, mainly with orthopterans. Three of the eight nests produced young that fledged. One nest was predated by both a Black-striped Capuchin Sapajus libidinosus and a Crane Hawk Geranospiza caerulescens, and another by a Black-tufted Marmoset Callithrix cf. penicillata. Nests were constructed in August, and the last nestlings fledged in late October. Most aspects of the breeding ecology of Casiornis are identical to those of other members of the Myiarchini.