Analysis of the geographic distribution and seasonal dynamics of Poospiza ornata (Landbeck, 1865; Passeriformes: Thraupidae)

Abstract

This study analyzes spatial and seasonal changes in the distribution of Cinnamon Warbling Finch (Poospiza ornata), a partially migratory passerine associated with arid environments in southern South America. Using occurrence records from GBIF (Global Biodiversity Information Facility) between 1999 and 2024, we estimated distributional range through cumulative convex hulls, analyzed centroid shifts, and evaluated seasonal distribution patterns. Results showed a progressive increase in occupied area (~1.1 million km² over 25 years) and an eastward centroid shift, with a marginal trend toward the north. Seasonal differences were evident, with broader distributions in spring and autumn, and higher densities during winter in the species’ core range. Although these findings suggest a recent range expansion—particularly toward the northeast (Uruguay and Paraguay)—we cannot conclusively state that a true expansion is occurring, as the patterns may be influenced by increasing sampling effort, particularly due to the rise of citizen science platforms. This study highlights the importance of continued spatial and temporal monitoring of Cinnamon Warbling Finch to determine whether current patterns reflect sporadic movements or an ongoing range expansion process driven by ecological and/or anthropogenic factors.