We present data pertaining to the nesting of 12 species of forest birds, based on opportunistic observations made between April and November 2018 in Humaitá Forest Reserve, Acre, in south-west Brazilian Amazonia. For some of these species, knowledge of their reproduction is still little known, e.g. Blue-tailed Emerald Chlorostilbon mellisugus, White-shouldered Antshrike Thamnophilus aethiops, Black-spotted Bare-eye Phlegopsis nigromaculata and Pink-throated Becard Pachyramphus minor. The data presented here help to fill gaps in the reproductive biology of these species in an ornithologically poorly known region.