Background: The Canguçu Research Station is located on the Javaés River, at the border between Araguaia National Park and the Cantão State Park in the Brazilian state of Tocantins. The habitat is at a diverse ecotone between Amazonian and cerrado Cerrado elementsbiomes, and is located within a fast-developing region undergoing conversion of natural habitats to planted pastures, rice and soy, in particular. Among other important contributions to the region’s biodiversity, the Javaés and Araguaia rivers conserve the largest remaining population of the Threatened Orinoco Goose (Neochen jubata) for the Ccerrado biome.

Objectives: We aimed to look at population status and threats to the region's waterbirds, including the threatened Orinoco Goose.

Methods: We compared past census data along the Araguaia and Javaés Rivers with newer (2017-2019) aerial, boat, and car-based surveys, maintaining a nearly monthly record of seasonal numbers. We also tracked a small number of geese using satellite telemetry.

Results: We demonstrate a nearly 50% decline in this important population over the previous decade, but also found large wet-season (non-breeding season) concentrations of Orinoco Geese in rice agrosystems, in associations with other waterbirds. Tracking results demonstrated a regional pattern of movement for the birds we tagged during the dry season breeding period. Tracking helped to locate an unexpected seasonal concentration of geese in nearby rice fields. These dense seasonal concentrations include birds from unknown areas, and are repeated annually, both geographically and seasonally.

Implications: We consider the potential threats to this Cerrado biome population of Orinoco Geese given these findings, which include habitat alteration, poaching, and spread of diseases. We discuss habitat and conservation needs of threatened species in the region, and recommend actions for local conservation authorities to ensure protection of the unique local habitats and fauna.