Unravelling the migratory pattern of a vulnerable South American passerine: the Chestnut Seedeater

ROSONI, J. R. R.; FONTANA, C. S.; CARLOS, C. J.

Gramado

Congreso; II Ornithological Congress of the Americas; 2023

Sociedade Brasileira de Ornitologia/Sociedad de Ornitología Neotropical/Association of Field Ornithologists

The movement ecology of migratory Sporophila species remains poorly understood. Specifically, Chestnut Seedeater Sporophila cinnamomea breeds in southern South America and is known to migrate to central Brazil. Our objective was to provide a comprehensive description of migratory routes, stopovers, and non-breeding areas using geolocators attached to 14 adult male individuals over three breeding seasons (October to March 2018–2021). Birds were captured using mist nets and marked with metal and colored plastic rings. Geolocators were configured to record light data at 5-minute intervals, which was then transformed into log lux data and employed to identify twilight events. Stopovers were defined as periods of 3–30 days, and Bayesian modeling was utilized to estimate migratory routes. Non-breeding areas were identified as locations utilized for over 30 days. Migration duration was calculated as the number of days between the first and last day spent in both breeding and non-breeding areas. The overall device recovery rate was 64% (n=9), with geolocators operating for 301 days. Autumn migration commenced on February 24th and extended for 46 days, encompassing 1,679 km, with an average of 2.38±0.92 stopovers—twice the number observed during spring migration (1.40±0.89). We identified eight non-breeding areas utilized for about 145 days, primarily within the Cerrado biome. Spring migration commenced in early September, lasting about 58 days, and covering 2,940 km. Our study provides valuable insights into this species´ migratory patterns. We urge the utilization of these findings to inform the planning and establishment of protected areas for conserving grassland species.