Geographical distribution of the Pinnated Bittern ( Botaurus pinnatus ): Update and seasonal movement pattern

The Pinnated Bittern Botaurus pinnatus (Ardeidae) is a widely distributed Neotropical wading bird whose distribution and seasonal status remain poorly resolved. Discrepancies among published literature, citizen science records and the range currently assumed by BirdLife International indicate that both its geographical distribution and migratory behaviour require reassessment. In this study, we aimed to (1) model the potential geographical distribution of the Pinnated Bittern, providing an updated range estimate based on environmental suitability and historical occurrence records; and (2) assess potential migratory movements by examining the spatiotemporal patterns of occurrence records across its range. We employed species distribution modelling using environmental variables hypothesized to influence its distribution, and analysed temporal dynamics of records along the temperate–tropical (latitudinal) and east–west (longitudinal) gradients divided into four zones of equal extent. Our results indicate a broader and more continuous distribution than currently recognized by BirdLife International, with ∼37% of cleaned occurrence records falling outside the official range polygon. Suitable areas were concentrated in lowland seasonal wetlands across much of the Neotropics, including the La Plata basin, Central America, the Llanos and the Brazilian coast. However, we found no evidence supporting either the hypothesized latitudinal or longitudinal seasonal movements, as occurrence records did not show consistent directional redistribution across the annual cycle. These results underscore the limited understanding of the species' true range and movement ecology in the Neotropical region. This lack of spatially explicit knowledge constrains ornithological research and conservation planning, particularly for cryptic and poorly studied species such as the Pinnated Bittern.