Intraspecific and Interspecific Aggregations and Habitat Use by Threatened Sheldgeese (Chloephaga Spp.) in Austral Patagonia, Argentina

FASOLA LAURA; COSSA NATALIA ANDREA; REBOREDA JUAN CARLOS; ROESLER IGNACIO

Congreso; North American Ornithological Conference; 2020

Studies about species aggregations and habitat use provide important information about the nature of the species and how those species meet their requirements, but also have key implications for its conservation and management. Migratory sheldgeese (Upland Goose Chloephaga picta, Ashy-headed Goose C. poliocephala and Ruddy-headed Goose C. rubidiceps) are threatened birds that breed in southern Patagonia. We studied the aggregation patterns of these species and thehabitat they use within part of their reproductive area by conducting nine road surveys between spring 2013 and summer 2016, covering 900 lineal km and 900 km2. Most groups (82.3%) were monospecific, but 16.4% included two of the species and 1.3% the three species. The most abundant species was the Upland Goose, which was present in 98% of the groups, followed by the Ashy-headed Goose in 18% of the groups. The Ruddy-headed Goose was present in only 3% ofthe groups, in only 15 sites and a maximum of 49 individuals were counted. Most individuals concentrated in grass lawns, meadows and Festuca grasslands. Groups were larger in meadows, wetlands and during summer and autumn (post-breeding). Population density increased from spring to autumn and decreased in winter, when 68-82% individuals migrate. Surveyed areawas probably a pre-migration concentration site, which would explain the larger groups in autumn. Our results provide resources to prioritize conservation actions by identifying important habitats and proper time of the year to apply these actions.