Resumen:
Se presenta información sobre la nidificación de 20 especies en las Yungas de Salta y Jujuy. Se describen fecha, localidad, forma, tamaño, materiales y contenido de los nidos hallados. Los nidos de Sittasomus griseieapillus, Poeeilurus seutatus, Syndaetyla rujosupereiliata, Todirostrum plumbeieeps y Contopusjumigatus, son poco conocidos. Se detectó a tres adultos trayendo alimento a un nido de Hirundinea jerruginea, y ayudantes se notaron en nidos de Cyanoeorax ehrysops. Los datos presentados permiten concluir que las especies consideradas nidifican durante la estación húmeda, salvo Phaethornis pretrei, que lo hace durante la estación seca.

Abstract:
We present dat on nesting of 20 bird species of the Yungas (montane forests) of Salta and Jujuy provinces. We provide information on date, location, shape, size, materials and contents of the nests. Breeding information is presented for the little-known nest of Sittasomus griseieapillus, Poecilurus seutatus, Syndaetyla rujosupereiliata, Todirostrum plumbeieeps and Contopus jumigatus. Chicks in a nest of Cliff Flycatchers Hirundinea jerruginea were fed by three adults. Helpers were detected in nests of Plush-capped Jays Cyanoeorax ehrysops. Most avian species bred principally in the wet season, but the hermit hmmingbird Phaethornis pretrei nested in the dry season.

Resumen:
A Reserva Biológica do Atol das Rocas, localizada a cerca de 250 Km a leste de Natal, Rio Grande do Norte, apresenta uma fauna abundante, notadamente pela sua avifauna marinha, nidificante ou visitante. Suas duas i1hotas, com aproximadamente 3 ha cada, abrigam as maiores colonias de reproduçao de atobá-mascarado Sula dactylatra e viuvinha-marrom Anous stolidus do Brasil, e a maior do trinta-réisdo- manto-negro Sterna fuscata do Atlântico Sul. Realizaram-se, em 1991, 1993 e 1994, coletas de dados biológicos deste grupo como, censos populacionais, mapeamento das áreas de nidifical,(ilo, confeclfao de ninhos, biometria e características de ovos, ninhegose adultos, além do anilhamento, recupera~oes de aves anilhadas e observaçoes de aspectos gerais, com o objetivo de se ter um maior conhecimento sobre a avifauna local. Os resultados indicam a existência de urna sazonalidade no periodo reprodutivo das espécies, que pode estar relacionada a estaçao climática, que por sua vez influencia sobre a vegetaçao local, tornando algumas áreas mais propícias a nidificaçao de determinadas espécies, além da abundância e ocorrência de determinadas espécies de peixes (presas) importantes em suas dietas alimentares, em algumas épocas do ano. Recuperaçoes de aves anilhadas demonstram que, certos indivíduos de atobá-marrom Sula leucogaster, nascidos em outros locais da costa brasileira, chegam ao Atol dasm Rocas para se estabelecerem, assim como o atobá-do-pé-vermelho Sula sula e a viuvinha- negra Anous minutus que utilizam a Reserva para o forrageamento, provenientes de Fernando de Noronha.

Abstract:
Reserva Biológica do Atol das Rocas is a marine biological reserve located about 250 Km west of Natal - Rio Grande do Norte, Brazil. It has an abundant fauna of visiting or nestíng seabirds. Its 2 islets, around 3 ha each, shelter the largest breeding colonies of Masked Booby Sula dactylatra and Brown Noddy Anous stolidus in Brazil and of Sooty Tern Sterna fuscata for the South Atlantic. Data on biological aspeets of the bird species were collected in 1991, 1993 and 1994. Field work included of population censuses; mapping of nesting areas, nest building; eggs, chicks and adults biometry and characterization; bird banding and recoveries, and general observations. The results indicate a breeding period seasonality, possible linked with climate. Climate also influences the local vegetation. The drier part of the year expandes the nesting habitat of Sterna fuscata and Anous stolidus (namely at Cemitério islet). The abundance and occurrence of fish species (preys) that are important on seabirds' diet, may also intluenee the nesting period. Recoveries of banded birds show some Sula leucogaster individuals that are born in other parts of the Brazilian coast and come to Rocas Atoll to settle. It also indicates that Sula sula and Anous minutus coming from Fernando de Noronha Is. use the reserve to forage.

Resumen:
Densidades lineales de aves (y mamíferos) fueron registradas a lo largo de cuatro tributarios del Paraná en la provincia de Misiones, Argentina. En una reciente expedición, se hicieron conteos a fin de determinar el status del Pato Serrucho (Mergus octosetaceus) en Argentina. Se examinó un total de 340 kilómetros de ríos, incluyendo secciones del Arroyo Uruzú, Urugua-í, Piray Miní y Piray Guazú, usando un bote inflable. Datos concernientes a la densidad de aves de río, rapaces y mamíferos acuáticos se presentan y discuten. Durante la expedición sólo un Pato Serrucho fue registrado y la conclusión inevitable es que la especie está en vias de extinción en Argentina.

Abstract:
The ocurrence of the Lesser Grass-finch (Emberizoides ypiranganus) is confirmed for Reserva El Bagual. Formosa Province, where it is a common resident. The nest and eggs are described. The species conservation status requires revision.

Resumen:
Sobre la base de 84 registros de Phaeomyias murina en el noreste de Argentina se brindan nuevas localidades de distribución y datos sobre los hábitats frecuentados, abundancia relativa, fenología, comportamiento y vocalización. Del total,62 ejemplares fueron detectados mediante dos tipos de censos realizados en el noroeste de Corrientes: conteos por puntos (41) y trayectos fijos (21); los restantes son registros ocasionales cuando se observaban aves en diversas localidades. En los censos, P. murina fue comunmente registrado en bosques semixerófilos abiertos de Schinopsis balansae (quebrachales) y no fue encontrado en la selva subtropical más húmeda. Sin embargo, ocho registros ocasionales fueron obtenidos en selvas subtropicales del noreste de Corrientes en sitios donde no existen quebrachales. En coincidencia con nuestras observaciones, varios autores indican preferencia por hábitats abiertos xéricos y semixéricos, aunque puede ser observado en una amplia variedad deambientes. Según los datos propios y la literatura P. murina se reproduce en Argentinaen primavera-verano y migra durante el otoño presumiblemente hacia el norte.

Abstract:
New distributional records, habitat utilization, relative abundance, migration, vocalization, behavior and descriptive features of the Mouse-coloured Tyrannulet (Phaeomyias murina) are given, based on 84 records from Northeastern Argentina. Two census techniques were used to detected 62 individuals in NW Corrientes: Points count (4) and transect (2). The remaining records were occasional observations from diferents sites. In the area censused P. murina was one the commonest birds in semixerophitic Chaco woodland of Schinopsis balansae, but was not found in humid subtropical forest. Nevertheless, eight occasional records were obtained in humid subtropical forest in NE Corrientes, where Chaco forest does not exist. In agreement with our observations, several authors point out that P. murina show a preference for arid to semiarid areas, although it could be found in a wide variety of habitats. The records show that this species breeds in Argentina during spring-summer and migrates, presumably north, during the fall.

Abstract:
We studied the breeding ecology of Imperial Shags (Phalacrocorax atriceps) in Deseada Island (Santa Cruz, Argentina), during the breeding season of 1994-95. The shags arrived to the island in early August, they re-builded their nests and started to lay eggs during late October, with a peak of egg production in the first two weeks of November. The modal clutch size was three eggs. Hatehing started in late November. The maximum mean brood size was observed in mid- Oecember (1.4 chicks). Hatehing success was 53%, whereas the survival of chicks was 60%. Nelther hatching success nor chick survival differed among nests located in distinct sectors of the colony. In mid- February the juvenile (approximately 60 days of age): adult ratio was 1:3. All the juvenile shags left the island in late March, together with most adults.

Abstract:
Quarenta conteúdos estomacais de sete espécies de Elaenia (Tyrannidae) foram analisados em relaçao ao volume de frutos e em relaçao ao tipo de ítem alimentar. A porcentagem média de frutos nos estomagos foi de 91 %. nao hayendo diferenças entre as espécies, nem entre as estaçoes seca e chuyosa. Estes dados associados a urna revisao da literatura revelam que o gênero Elaenia é altamente frugívoro, consumindo pelo menos 51 espécies de frutos de 30 famílias de plantas.

Abstract:
On the basis of five specimens at the MACN collection, the population of Lophonetta specularioides from the province of Mendoza seems somewhat intermediate between northern birds (subsp. alticola) and southern birds (Subsp, specularioides). Based on specimens of Merganetta a. armata we extend the distribution of this subspecies northward by about 320 km in the province of San Juan.

Abstract:
Five nests of the Barred Antshrike (Thamnophilus doliatus) were studied at the southern extreme of its distribution, in Formosa Province, Argentina. The laying interval was alternate days. The incubation period was 15 days and the nestling period 12-13 days. Nesting success was 33, 3 %. Brood parasitism of the Shiny Cowbird (Molothrus bonarienis) on nests of this antbird is reported for the first time. Clutch size seems to be about two eggs throughout the species ranges, but further information on this point is needed.

Abstract:
The Crowned Eagle, Harpyhaliaetus coronatus, is regarded as endangered because of its low population numbers, the destruction of potential habitat, and the scarcity of records. Ecological studies on this species are required to develop conservation plans. We present 15 new distributional records obtained in the last 11 years. Based on the frequency of observed individuals and groups, and on the continuity of the habitats where it was recorded, we propose a priority area for ecological research on this species.

Resumen:
Los estudios de aves marinas entre las Islas Shetland del Sur y el norte de la península Antártica son numerosos durante el verano, mientras fuera de esta época son escasos en esta zona. El objetivo de este estudio fue registrar las especies de aves presentes en otoño en la zona comprendida entre el norte de la península Antártica y las islas Shetland del Sur. Las observaciones fueron hechas abordo del Rompehielos Alte. lrizar; se realizaron censos de 10 minutos seguidos de lO minutos de intervalo. durante el fotopedodo. Se calculó el índice de diversidad de Shannon. Fueron registradas 13 especies; se relaciona la aparición de estas aves en la zona en esta época con variables ambientales.

Abstract:
Seabirds

Abstract:
While reviewing the seabird collection stored at Museo Argentino de Ciencias Naturales, we found a specimen of the Pink-footed Shearwater Puffinus ereatopus that had been collected on May 1981 at Punta Conos, golfo San José, Chubut province, by G. Harris. Plumage and measurements agree with those of the species, allowing a straight and c1ear identification. This is the first record of the species for Argentina, and also for the Atlantic Ocean.

Abstract:
We report the observation of a Giant Conebill Oreomanes fraseri, the fírst record of this species for Argentina, and the southem most so far. The single bird was seen on 26 September 1997 in the steep-sided quebrada of the rio Peña Negra, about 10 km west of Rodeo Pampa, Salta at ca. 3150 m. Based on colour pattern we assume it was an immature. We found the bird in a partially logged Polylepis (Rosaceae) woodland. This habitat is being generally c1eared all over its range, giving a strong cause of concern for the conservation of this near-threatened species, and several others that share this habitat.

Resumen:
Evaluamos el efecto de una ruta como inhibidora del desplazamiento de las aves, dentro de La Reserva Provincial La Florida (Tucumán, Argentina). Esta ruta divide la reserva, separando un fragmento del resto del bosque. Durante 12 meses realizamos muestreos mensuales de aves con redes de niebla instaladas a ambos lados de la ruta, y censamos las aves que atraviesan la ruta. Los individuos capturados fueron clasificados en sedentarios (capturados más de una vez) y transeúntes (1 captura). Si la ruta inhibe la llegada de nuevos individuos al fragmento (FG), el porcentaje de aves sedentarias en este sitio debería ser mayor que en el bosque continuo (BC). En las redes capturamos 1742 aves (34 especies); la riqueza fue similar para ambos sitios (27 vs. 28). El número de sedentarios no mostró diferencias entre sitios (BC=234, FG=194), al igual que el porcentaje mensual de aves sedentarias capturadas. Los transeúntes fueron más abundantes en el BC (809 vs. 505); la abundancia de Turdus rufiventris fue responsable de esta diferencia. En los censos en la ruta observamos 622 aves (28 especies). La cantidad de registros de T. rufiventris cruzando la ruta (33.8% del total de aves censadas) indicaría que esta barrera no afecta sus desplazamientos. Algunas especies frecuentes en las redes, fueron poco o no fueron detectadas cruzando la ruta, sugiriendo que sus desplazamientos podrían estar inhibidos por la ruta. Sin embargó, ninguna de estas especies mostró diferencias entre sitios en el porcentaje de aves sedentarias capturadas mensualmente. Los resultados de este trabajo sugieren que las aves estudiadas no están significativamente afectadas por la discontinuidad producida por la ruta. Estos resultados podrían no ser extrapolables a otras áreas de bosque, que requirirían estudios propios.

Abstract:
We studied the effect of a road on bird movements at La Florida Provincial Reserve (Tucumán, Argentina). A road cuts the reserve leaving a forest fragment detached from the continuous forest. Understory birds were captured monthly for 12 months using 12-15 mist nets located in forest sites on both sides of the road, and birds crossing the road were censused to estimate movement between the fragment (FG) and the continuous forest (CF). The captured birds were classified as site-attached (captured more than once) and transient individuals (one capture). If the road reduced the arrival of new individuals into the FG, the proportion of site-attached captures would be expected to be larger here than in the CF. We captured 1742 birds (34 species). Richness was similar for both sites (CF=27, FG=28). Site-attached abundance showed no differences between sites (CF=234, FG= 194), as well as the percentage of site-attached birds captured monthly. Transient individuals were significantly more abundant in continuous forest (809 vs. 505); Turdus rujiventris abundance was responsible for this difference. In censuses we observed 622 individuals (28 species). The high frequency of T. rujiventris individuals crossing the road (33.8% from total birds censused) suggests that this barrier should not affect their movements. Some species commonly captured in the nets were not detected crossing the road, suggesting that they may be affected by the road. However, none of these species showed differences between sites in the percentage of site-attached captured monthly. Finally, our results suggest that understory birds are not significantly affected by the discontinuity produced by the road. These results could not always be extrapolated to other forests, that would require particular studies.