Citizen Science for the Knowledge of Brazilian Birds: Breeding Aspects of the Horned Sungem (Heliactin bilophus) (Aves, Trochilidae) in the Brazilian Cerrado

Abstract

Photographic records produced by citizen scientists have been used by professional ornithologists to study tropical birds. Near 90 species of hummingbirds occur in Brazil, and few of them have had aspects of their breeding investigated in detail. The Horned Sungem Heliactin bilophus is a small hummingbird commonly found in central Brazil, and remains poorly known. This study aimed to investigate breeding aspects of H. bilophus in the Brazilian Cerrado through the use of citizen science data. Searches for photographic records were conducted in three online databases in April 2022. Records with evidences of breeding activities (n = 35) were obtained by citizens along 15 years, and included in this study. Most of them (89%) were obtained in the WikiAves database. They were obtained mainly in central and southeastern Cerrado. Nests were cup-shaped, and fixed to forking branches of shrubs. Most records involved nests, while a minor portion referred to young photographed outside nests. Only female adults were associated with nests or young. Clutch size was always two eggs (n = 6). One or two young were found per nest (n = 10). Most records (66%) occurred in the dry season, and fewer of them (34%) were obtained in the rainy season. They were concentrated during the whole dry season, and the late rainy season, having occurred scarcely in other periods of the year. Each phase of the breeding season (nest building, nests with eggs, downy young, greenish young in nests, and fledged young) lasted for 5-7 months. The breeding season of the Horned Sungem in the Brazilian Cerrado comprises at least 10 months, a period much longer than that considered in previous literature. This study suggests that photographic records available in citizen science databases can improve the knowledge of breeding aspects of hummingbird species found in Brazil.