Beak deformities in north Patagonian birds

Abstract

Within the last decade, many individuals of several bird species with abnormal and strange beaks deformationshave been reported from Alaska, United States, and from United Kingdom and Ireland. Different forms of beakdeformities were observed, but the causes of these abnormalities are unknown. We report beak deformities in twospecies of birds in northwestern Patagonia, Argentina: Austral Thrush (Turdus falcklandii) and Patagonian Mockingbird(Mimus patagonicus). Between 2013 and 2016, we captured individuals of White‐crested Elaenia (Elaenia albiceps, N= 305), Rufous‐collared Sparrow (Zonotrichia capensis, N = 119), Austral Thrush (N = 100), Black‐chinned Siskin (Spinusbarbata, N = 64), Patagonian Sierra‐Finch (Phrygilus patagonicus, N = 48) and Gray‐hooded Sierra‐Finch (Phrygilusgayi, N = 40) in surroundings of Esquel city, located in western Patagonia, Chubut province, and quantified the prevalenceof beak deformities. Only adult Austral Thrushes (5 out of 78; 6.41%) showed abnormal beaks. Neither juvenilethrushes (N = 22) nor the other five species showed beak deformations. Austral Thrushes with beak deformationswere also observed and photographed (but not captured) in other areas around the city. We also photographed onePatagonian Mockingbird with an abnormal beak near Las Plumas Village, Chubut province. Beak deformities variedfrom light to severe, and also in their form. Most of them were characterized by an elongated and often decurvedupper mandible, producing an overbite; in other individuals both mandibles were elongated and sometimes crossedor had a pronounced gap. Most affected birds showed signs of improper preening, and one of them was malnourished.All of these characteristics are similar to those described for birds affected by avian keratin disorder in NorthAmerica. Further research is needed to detect potential presence of other species with beak deformities in Patagonia,to find out possible causes of such deformities, and to determine whether these anomalies are associated with naturalhabitats or urban environments.Fil: Gorosito, Cristian Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagóica. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Esquel. Centro de Investigación Esquel de Montaña y Estepa Patagónica; ArgentinaFil: Gonda, Héctor Eduardo. Centro de Investigación y Extensión Forestal Andino Patagónico; Argentina. Universidad Nacional de la Patagonia "san Juan Bosco". Facultad de Ingeniería - Sede Esquel; ArgentinaFil: Cueto, Víctor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagóica. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Esquel. Centro de Investigación Esquel de Montaña y Estepa Patagónica; Argentin