Demography of the Neotropical austral migrant Elaenia albiceps chilensis (Tyrannidae) on its breeding grounds: climate and food offer effects

PRESTI, P; AMICO, GC; BRAVO, SP; CUETO, VC

ARARAJUBA: REVISTA BRASILEIRA DE ORNITOLOGIA

SOC BRASILEIRA ORNITOLOGIA

Lugar: Pelotas, RS; Año: 2018 p. 240 - 250

0103-5657

Th e White-crested Elaenia (Elaenia albiceps chilensis) is a Neotropical austral migrant that breeds in Patagonian forestsand overwinter in South America tropics. We investigated White-crested Elaenia demography and the environmental conditionsthe specie is subjected at the northwest of Patagonia as a fi rst attempt to elucidate its population dynamic. We studied the speciesabundance, individuals´ body condition, survival, productivity of young and site fi delity according to changes in rainfall patterns andfood supply, during three breeding seasons (2009 to 2012). We color banded 361 adult and juvenile White-crested Elaenias. Duringthe fi rst studied season, precipitations were remarkably above the mean and ripe fruit supply was lower than in the other seasons,whereas the abundance of arthropods remained similar along the study. Th e species abundance decreased 50% across the study,while adult apparent survival rate, the number of breeding females, young productivity and site fi delity were 50% lower in the fi rstseason in comparison to the following seasons. Females presented lower body condition at arrival in the fi rst two studied periods. Sitefi delity diminished after unfavorable breeding season (i.e. low young productivity and fruit supply), especially for males, althoughthey were more faithful than females and had a slightly higher apparent survival rate. Our results suggest that White-crested Elaeniademography is aff ected by changes in its main food resource supply (fl eshy fruits) during the breeding season, indicating that thispart of the annual cycle could be fundamental for its population dynamic.