Nesting of the Aplomado Falcon (<i>Falco f. femoralis </i> )in San Luis province

In this paper we describe the activity of a nesting pair of Aplomado Falcons (Falco f.femoralis) during the first days of the nestling period. The nest was found in a Chañar tree (Geoffroea decorticans) at a heíght of 4.5 m in San Luis province. The female remained at the nest 94.14% of the observation time (brooding: 86.90%) and fed thc nestlings with arate of 0.47 items/h. Feeding periods lasted in average 560 sec (Ra: 360-780 scc; n:9). The male was seen on the nest 1.28% of the obscrvation time and brought prcy with a frequency of 0.41 items/h. Information of nest and nestling characteristics, territory, defense, caching behavior and vocalizations is also given. Finally we provide a compilation about nesting ofthc Aplomado Falcon in Argentina

Live mammal prey (Zaedyus pichiy) in a nest of the black-chested Buzzard-Eagle (Geranoaetus melanoleucus)

Volume: 38Start Page: 101End Page: 10

Nesting of the Aplomado Falcon (<i>Falco f. femoralis </i> )in San Luis province

In this paper we describe the activity of a nesting pair of Aplomado Falcons (Falco f.femoralis) during the first days of the nestling period. The nest was found in a Chañar tree (Geoffroea decorticans) at a heíght of 4.5 m in San Luis province. The female remained at the nest 94.14% of the observation time (brooding: 86.90%) and fed thc nestlings with arate of 0.47 items/h. Feeding periods lasted in average 560 sec (Ra: 360-780 scc; n:9). The male was seen on the nest 1.28% of the obscrvation time and brought prcy with a frequency of 0.41 items/h. Information of nest and nestling characteristics, territory, defense, caching behavior and vocalizations is also given. Finally we provide a compilation about nesting ofthc Aplomado Falcon in Argentina

Nidificación del Halconcito Colorado (<i>Falco sparverius</i>) en la Patagonia

The breeding cycle in estancia "El Cuadro" (47º 40' S, 68º W) begins in september and ends in january. Five of six nests found were placed in basaltic cliff holes, the remaining in an abandoned dove col. The mean height of the nests was 4,7 m. while the density of nesting pairs was 0,038/km2. There productive success of five nests was of 3,2 nestlings nest. Finally we describe some aspects of reproductive behavior

Breeding biology of grey-eagle buzzard (<i>Geranoaetus melanoleucus</i>) in Southern Patagonia, Argentina

La biología reproductiva de Geranoaetus melanoleucus fue estudiada en el departamento Deseado, provincia de Santa Cruz, entre septiembre de 1987 y enero de 1988. La temporada reproductiva se extendió, al menos, desde septiembre hasta fines de enero, cuando todos los pichones alcanzaron las ocho semanas de edad. Se encontraron seis parejas nidificando en un área de 130 km², con una densidad de una pareja cada 21.6 km². Todos los nidos estaban ubicados en paredones basálticos, entre 2.8 y 20 m (promedio 8.99 m) de altura. Algunas parejas tenían nidos alternativos en su territorio de nidificación. La postura promedio para seis nidos fue de 2.5 huevos. El período de incubación medido en tres nidos tuvo un rango de 37 a 42 días. La eclosión ocurrió entre el 7 y el 22 de noviembre, con un éxito de eclosión del 100%. Cinco de las seis parejas (83.3%) criaron exitosamente al menos un pichón. El éxito de cría fue de 1.67 pichones por pareja. Fueron registradas cuatro vocalizaciones diferentes para los adultos y dos para los pichones. Se describen las cópulas y el desarrollo de los pichones. Las Águilas Moras parecían tolerar a muchas especies, incluso a otras águilas, pero sufrían frecuentemente los ataques de Falco sparverius y Circus cinereus. El ataque de las águilas hacia estas especies fue también notado. La liebre europea (Lepus europaeus) fue la presa más aportada a los pichones en el nido.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