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This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Avian siblicide is the consequence of extreme sibling aggression in the nest. However, sibling rivalry does not always lead to brood reduction. Depending on the frequency of this behavior in the population and the results of the attacks, siblicide is classified as obligate or facultative. During one breeding season we observed the nests of two different pairs of Black-Chested Buzzard-Eagle in central Chile. The brood size of nests was of 2-3 chicks; then, 5-7 days after hatching, the first sibling aggression were observed in both nests, characterized by vigorous attacks from the both older and younger chick. This behavior extended up to 20-25 days after hatching with no brood reduction. This work represents the first detailed record of sibling aggression in a diurnal raptor in Chile, providing additional evidence for considering the Black-Chested Buzzard-Eagle as a facultative siblicide.

Hematological and biochemical parameters are useful indicators of raptor health. However, there is still a paucity of such data for many species, including the Black-chested Buzzard-Eagle (Geranoaetus melanoleucus), native to South America. The goal of this study was to determine hematology and blood chemistry reference intervals in 31 captive Black-chested Buzzard-Eagles held at a raptor rehabilitation center in central Chile. We report parameters of interest such as the mean ± SD, and reference intervals for this group of birds using 90% confidence intervals. Measured hematological parameters included red blood cell count, packed cell volume, hemoglobin concentration, Wintrobe indices, and total and differential leukocyte counts. Measured biochemical parameters included aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and creatine kinase activities; and glucose, lipids, proteins, electrolytes, and uric acid plasmatic concentration. All Black-chested Buzzard-Eagle samples were negative for hemoparasites. Establishing reference intervals for hematological and biochemical parameters in the Black-chested Buzzard-Eagle adds to the body of knowledge of health indicators for this raptor species, contributes to its management and ex-situ conservation, and helps identify future research needs.