Keywords
breeding biology
diet
Geranoaetus melanoleucus
Patagonia
Santa Cruz
Abstract
The breeding biology of Grey Eagle-Buzzard Geranoaetus melanoleucus was studied at Deseado department, Santa Cruz province, Argentina, between September 1987 and January 1988. The breeding period, as observed, extended at least from September to late January, when all birds reached an age of eight weeks. Six breeding pairs were found in 130 km2, with a density of one pair per 21.6 km2. All nests were placed in basaltic cliffs, between 2.8 and 20 m height (mean 8.99 m). Alternative nests were found for some pairs in their nesting range. Clutch size was 2.5 eggs for six pairs. Incubation period for three nesting pairs ranged between 37 and 42 days. Hatching occurred between November 7 and 22, with a hatching success of 100%. Five pairs out of six (83.3%) successfully raised at least one chick. Breeding success was 1.67 nestlings per pair. Four vocalizations were recorded for adults and two for nestlings. Mating and nestling development are described. Eagles appeared to be tolerant to some raptors in the area, including other eagles, but suffered the attacks of Falco sparverius and Circus cinereus. Attacks of eagles upon these raptors were also noted. European hare (Lepus europaeus) was the main prey brought to the nestlings.
References
AMADON D (1982) A revision of the sub-buteoninehawks (Accipitridae, Aves). American MuseumNovitates 2741:1ñ20
BLAKE ER (1977) Manual of Neotropical birds. Volume 1.University of Chicago Press, Chicago
BONINO N (1986) La liebre como problema, mÈtodos decontrol. Especies N∞ 3, Serie Folletines Fauna Silves-tre, INTA
BROWN L Y AMADON D (1968) Eagles, hawks and falconsof the world. Country Life Books, Feltham
BUSTAMANTE JJ, DON¡ZAR A, HIRALDO F, CEBALLOS O YTRAVAINI A (1997) Differential habitat selection byimmature and adult Grey Eagle-BuzzardsGeranoaetus melanoleucus. Ibis 139:322ñ330
CABRERA AL (1976) Regiones fitogeogr·ficas argen-tinas. Pp. 1ñ85 en: Enciclopedia argentina de agri-cultura y jardinerÌa. Tomo II. FascÌculo 1. ACME,Buenos Aires
CANEVARI M, CANEVARI P, CARRIZO GR, HARRIS G,RODRÕGUEZ MATA J Y STRANECK RJ (1991) Nueva guÌade las aves argentinas. Volumen 1. FundaciÛn Acindar,Buenos Aires
DE LUCCA ER Y SAGGESE MD (1995) Fratricidio en el¡guila Mora Geranoaetus melanoleucus. Hornero14:38ñ39
DON¡ZAR JA, CEVALLOS O, TRAVAINI A E HIRALDO F(1993) Roadside raptors surveys in the ArgentineanPatagonia. Journal of Raptor Research 27:106ñ110
HIRALDO F, DON¡ZAR JA, CEBALLOS O, TRAVAINI A,BUSTAMANTE J Y FUNES M (1995) Breeding biology ofa Grey Eagle-Buzzard population in Patagonia. Wil-son Bulletin 107:675ñ685
HOUSSE R (1945) Las aves de Chile en su clasificaciÛnmoderna: su vida y costumbres. Ediciones de la Uni-versidad de Chile, Santiago
DEL HOYO J, ELLIOT A Y SARGATAL J (1994) Handbook ofthe birds of the world. Volume 2. New World vultures toguineafowl. Lynx Edicions, Barcelona
IRIARTE JA, FRANKLIN WL Y JOHNSON WE (1990) Dietsof sympatric raptors in southern Chile. Journal ofRaptor Research 24:41ñ46
JIM...NEZ JE Y JAKSIC FM (1989) Behavioral ecology ofGrey Eagle-buzzards, Geranoaetus melanoleucus, incentral Chile. Condor 91:913ñ921
JIM...NEZ JE Y JAKSIC FM (1990) Historia natural del¡guila Geranoaetus melanoleucus: una revisiÛn. Hor-nero 13:97ñ110JOHNSGARD P (1990) Hawks, eagles and falcons of NorthAmerica. Smithsonian Institution Press, Washington DC
LEHNER PN (1979) Handbook of ethological methods.Garland Press, New York
MASSOIA E Y PARDI—AS U (1986) Algunos mamÌferosdepredados por Geranoaetus melanoleucus enCorralitos, Pilcaniyeu, RÌo Negro. Acintacnia 23:24ñ26
NEWTON I (1979) Population ecology of raptors. ButeoBooks, Vermillion
OLROG CC (1979a) Nueva lista de la avifauna argen-tina. Opera Lilloana 27:1ñ324
OLROG CC (1979b) Alarmante escasez de rapaces enel sur argentino. Hornero 12:82ñ84
PAVEZ EF, GONZ¡LES CA Y JIM...NEZ JE (1992) Diet shiftsof Black-Chested Eagles (Geranoaetus melanoleucus)from native prey to European rabbits in Chile. Jour-nal of Raptor Research 26:27ñ32
SCHLATTER RP, Y¡—EZ JL Y JAKSIC FM (1980) Food-nicherelationships between Chilean Eagles and Red-Backed Buzzards in central Chile. Auk 97:897ñ898
TRAVAINI A, DON¡ZAR JA, CEBALLOS O, FUNES M,RODRIGUEZ A, BUSTAMANTE J, DELIBES M E HIRALDO F(1994) Nest-site characteristics of four raptor spe-cies in the Argentinian Patagonia. Wilson Bulletin106:753ñ757
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.