The islands of the Wallacean biodiversity hotspot support diverse and highly endemic bird communities, yet remain ornithologically poorly studied. There is a particular paucity of data regarding breeding biology for the region's birds. Here, we help to address this research gap by collating observations of breeding evidence made during nearly 20 years of field work between 1999 and 2018 in south-east Sulawesi and its offshore islands. Data were collected between April and September, with a special focus on July and August, which is the dry season across the southern half of Sulawesi. In total, we summarise 1,064 observations of potential breeding in 66 species, of which 27 are Wallacean endemics (including the Critically Endangered Maleo Macrocephalon maleo), and 39 species of wider range (including the Endangered Milky Stork Mycteria cinerea). Records include species with little or no previously published information on their breeding biology, such as Pygmy Hanging Parrot Loriculus exilis, Sulawesi Pitta Erythropitta celebensis and an undescribed Zosterops species, provisionally referred to as Wangi-wangi White-eye.
