Resumen:
Durante 1991 y 1993 relevamos las costas de la Península Valdés , identificando cinco colonias de Pingüinos Patagónicos (Spileniscus magellanicus): Isla de los Pájaros, Estancia San Lorenzo, Caleta Externa, Islas de la Caleta yCaleta Interna. El número de nidos activos en Isla de los Pájaros fue 47. La colonia de Estancia San Lorenzo, con 17034 ±2553 nidos activos en 1993, ocupó un área de 73 ha (3 km de largo y entre 50 y 450 m de ancho) y presentó una densidad media de 2,43 nidos/100 m2. Durante Octubre de 1994 se localizó un asentamiento de 483 nidos activos a 4 km al W de esta colonia. La colonia de Caleta Externa, con 10973 ± 1807 nidos activos, se extendió 5 km de largo y entre 100 Y 500 m de ancho. La densidad de nidificación fue significativamente más alta en 1993 (0.77 nidos/IOO m2) que en 1991 (0.50nidos/l 00 m2). La colonia de Islas de la Caleta, con 9456 y 13780 nidos activos en 1991 y 1993, respectivamente, abarcó 21 ha en la costa SE de la isla Primera. Durante 1993, se hallaron 38 nuevos nidos en la isla Segunda y 19 nidos frente a la isla Primera, sobre la costa occidental de la Caleta Valdés. Finalmente, la colonia de Caleta Interna, con 1281 y 1553 nidos activos en 1991 y 1993, respectivamente, se extendió en forma discontinua a lo largo de 4,7 km de costa. El aumento en el número de nidos observado en las colonias estudiadas sugiere que la población estaría reclutando individuos provenientes de colonias cercanas a la Península Valdés . A pesar de la expansión poblacional observada, la actual tendencia en el aprovechamiento de los recursos naturales de la Península Valdés con objetivos turísticos y en el desarrollo costero de zonas aledañas requiere de la elaboración cuidadosa de pautas de manejo para minimizar el impacto sobre el Pingüino Patagónico.

Abstract:
Update of the Population Status of Magellanic Penguins in Peninsula Valdes, Chubut, Argentina. During 1991 and 1993 we surveyed the coasts of Península Valdés , identifying five colonies of Magellanic penguins(SpilenisClls magellanicus): Isla de los Pájaros, Estancia San Lorenzo, Caleta Externa, Islas de la Caleta and Caleta Interna.At Isla de los Pájaros there were 47 active nests. The Estancia San Lorenzo colon y, with 17034 ± 2553 active nests in 1993,occupied an area of 73 ha (3 km long by 50 and 450 m wide) and presented a mean nesting density of 2,43 nests/l 00 m2.During october 1994 we found a small settlement of 483 active nests about 4 km W of this colony. The Caleta External colony, with 10973 ± 1807 active nests, extended 5 km long and 100 and 500 m wide. Nesting density was significantly higher in 1993 (0.77 nests/100 m2) than during 1991 (0.50 nests/100 m2). The Islas de la Caleta colony, with 9456 and 13780 active nests in 1991 and 1993, respectively, occupied 21 ha on the SE coast of lsla Primera. During 1993, we found38 new nests at Isla Segunda and 19 nests infront of Isla Primera, on the W coast of Caleta Valdés. Finally, the Caleta Internacolony, with 1281 and 1553 active nests in 1991 and 1993, respectively, extended in patches along 4,7 km of coastline. The observed increase in the number of nests suggests that the population is recruiting individuals from colonies close to Península Valdés . Even though the population is increasing, the recruitment in the use of natural resources in PenínsulaValdés for tourist purposes and the coastal development of near by areas requires careful design of management guidelines to minimize the impact on Magellanic penguins.

Abstract:
In our study about the breeding biology of the Blackish Oystercatcher Haematopus ater, conducted during 1991/92 breeding season, the laying period started at the end of the second week of October and finished at the end of November. Mean clutch size was 1.8 (sd= 0.4, n= 26, modal clutch size= 2), while the mean laying interval between the first and second eggs laid in the same clutch was 2.8 days (s.d.= 1.4, n= 16). The laying-hatching intervals averaged : 28 days (s.d.= 2.5, n= 11). Hatchings occured between the second week of November and the first week of December and mean hatching interval was 1.8 days (s.d.= 0.5, n= 5).

Resumen:
La biología reproductiva de la Gaviota Capucho Café (Larus maculipennis) fue estudiada durante 1992 y 1993 en lagunas artificiales de Trelew, Chubut. El tamaño de la colonia se estimó en 2310 parejas. Las gaviotas comenzaron a visitar las lagunas a fines de setiembre y comenzaron a establecer territorios a principios de octubre. Los nidos fueron construidos sobre islotes de juncos, arbustos secos emergentes y en zonas de poca profundidad, sobre pilas de material acumulado sobre el fondo. Las parejas se asentaron significativamente más temprano sobre la vegetación emergente más alejada de la costa. La puesta se inició durante la primera semana de octubre, el tamaño promedio de la nidada fue de 2,57 huevos por día y el período de incubación fue de aprox. 23 días. Los primeros pichones eclosionaron a principios de noviembre y comenzaron a alejarse de los territorios a las 5 semanas de vida. Los pichones presentaron muy baja movilidad, permaneciendo mayormente sobre las plataformas de nidificación durante las primeras 4 semanas de vida. Las gaviotas no se alimentaron en o cerca de las lagunas donde nidificaron y los insectos formaron una parte importante de su dieta.

Abstract:
We studied the breeding biology of the Brown-Hooded Gull (La rus maculipennis) at artificial lagoons inTrelew, Chubut. We estimated colony size in 2310 breeding pairs. Gulls started to visit the lagoons during late september and to establish territories in early october. Nests were built on islands formed by Scirpus sp., emergent dead bushes, and on top of piles of debris in shallow waters. Gulls settled significantly earlier on the emergent vegetation furthest away fromthe coast. Egg-Iaying started during the first week of october, average clutch size was 2,57 eggs per nest, and the incubation period was approximately 23 days. Chicks started to hatch in early november and started to leave their territories at 5 weeks of age. Chicks showed low levels of mobility, remaining on the nest platforms for their first four weeks of age. Gulls didnot forage in or close to the lagoons where they bred and insects were an important part of their die!.

Resumen:
Seasonal abundance and distribution of plovers and sandpipers on the shores of the Golfo Nuevo, in the vicinity of Puerto Madryn were analyzed. Weekly census were made from April 1984 to September 1986. Twelve species of plovers and sandpipers were identified. The seasonal abundance of the most common species (Charadrius falklandicus, Calidris alba, Calidris fuscicollis, Calidris bairdii and Pluvianellus socialis) was related with the mean weekly amplitude of the photoperiod for this latitude. Acording to the timing of arrival, departure and the length of time the species remained in the area. Three behavioural patters were identified. Shorebirds concentrated on the shores of Puerto Madryn whenever the photoperiod amplitude is between 14 hrs of dayligth at lhe early March and 13 hrs of dayligth at the end of September. When the photoperiod amplitude reaches maximum values (summer) these shorebirds were not present.

Abstract:
Concentrations of Manx Shearwater off San Antonio, Oeste Rio Negro, Argentina, and an apparently undescribed behaviour of the species is reported.

Abstract:
Seasonal abundance and distribution of plovers and sandpipers on the shores of the Golfo Nuevo, in the vicinity of Puerto Madryn were analyzed. Weekly census were made from April 1984 to September 1986. Twelve species of plovers and sandpipers were identified. The seasonal abundance of the most common species (Charadrius falklandicus, Calidris alba, Calidris fuscicollis, Calidris bairdii and Pluvianellus socialis) was related with the mean weekly amplitude of the photoperiod for this latitude. Acording to the timing of arrival, departure and the length of time the species remained in the area. Three behavioural patters were identified. Shorebirds concentrated on the shores of Puerto Madryn whenever the photoperiod amplitude is between 14 hrs of dayligth at lhe earIy March and 13 hrs of dayligth at the end of September. When the photoperiod amplitude reaches maximum values (summer) these shorebirds were not present.

Abstract:
First records for Argentina of the Tawny-rumped Tyrannulet (Phyllomyias uropygialis) and the Slate-throated Redstart (Myioborus miniatus) in Baritu National Park, in northern province of Salta.

Resumen:
Se estudió la alimentación invernal y estival del Picaflor Cometa (Sappho sparganura) en tres localidades de las sierras de Córdoba. Este es el único picaflor que permanece en invierno en la provincia y a lo largo del año realiza desplazamientos altitudinales siguiendo la floración de diferentes especies. Aunque utiliza en forma indistinta plantas nativas e introducidas, incluso no especializadas para la ornitofilia, interactúa fuertemente con cinco especies indígenas: todas ellas son ornitófilas y S. sparganura sería un elemento importante para su reproducción. No obstante ello, en dos de los sitios una planta exótica (Chaenomeles lagenaria) fue la que posibilitó la permanencia del picaflor en los inviernos más fríos.

Abstract:
Summer and winter foraging of the Red-tailed Comet (Sappho sparganura) was studied in three sites in the Córdoba mountain range. This is the only hummingbird species overwintering in the province. Along the entire year it does altitudinal movements looking for different blooming plants. Although the Red-tailed Comet does not discriminate between native or introduced plants, feeding even on non-ornithophilous ones, it strongly interacts with five indigenous species. All of them are ornithophilous species and the hummingbirdís visits would be important for reproduction of these plants. However, in two of the sites an exotic species (Chaenomeles lagenaria) was the most important resource allowing overwintering of the Red-tailed Comet in colder years.

Abstract:
Siblicide was observed in the Black Chested Buzzard Eagle. Aggression between nest mates was seen in three out of five nests in study. Two nestlings from two of these nests died within the first ten days of hatching (one was found dead at the base of the nesting c1iff).A third nest also suffered early brood reduction probably due to this phenomenon. In the study area the species seems to behave as a facultative cainist.

Resumen:
Realizo una revisión de la literatura publicada sobre la historia natural del Aguilucho Común Buteo polyosoma complementada con mis observaciones de campo a lo largo de Chile, en particular de dos localidades: San Carlos de Apoquindo, 20 km al E de Santiago, y la Reserva Nacional Las Chinchillas, en Aucó, 300 km al N de Santiago. Además presento información cuantitativa de la dieta en Chile centro-N. La revisión la divido en 13 temas: distribución y taxonomía;nombres comunes; color del plumaje e identificación; morfometría y peso; historia de vida y reproducción; uso del hábitat; dieta; ritmos de actividad, tipos de vuelo y conductas de caza; agresión; vocalizaciones; abundancia; mortalidad; y otros hábitos. Con este trabajo se actualiza la información disponible para la especie y se la hace más accesible a la comunicad cientifica latino americana.

Abstract:
In this papel I review the available literature on the natural history of the Red-backed Hawk, Buteo polyosoma. I supplement it with my own observations throughout Chile, specially my detailed studies at San Carlos de Apoquindo, 20 km E Santiago, and at Chinchilla National Reserve, at Aucó, 300 km N Santiago. I also document the diet of Red-backed hawks qualitatively in the second site. There view was covered in thirteen topics: Distribution and taxonomy; common names; color and field identification; morphometry and weight; life history and reproduction; habitat use; diet; activity, flight modes and hunting behavior; aggressions;vocalizations; abundance; mortality; and other topics. With this work, the current knowledge of the natural history of the Red-backed Hawk is updated, and made more accessible to the latinamerican scientific community.

Resumen:
Entre noviembre de 1988 y octubre de 1989 se estudiaron los cambios en la composición de especies de lacomunidad de aves acuáticas de la Reserva Costanera Sur y se cuantificaron las variaciones de la abundancia local de los gremios y de las especies más importantes. Debido a una fuerte sequía la superficie anegada de las lagunas se redujo notablemente durante el verano. Esto provocó una brusca disminución en el número de especies y esta situación generó altos valores de disimilitud cualitativa entre muestreos durante ese período. Posteriormente, las especies fueron retornando a la Reserva a medida que las lagunas se iban rellenando, sin observarse cambios marcados en la composición específica. Los gremios y las poblaciones de aves acuáticas mostraron importantes fluctuaciones numéricas. Todas las especies se perjudicaron por la falta de agua, pero tuvieron distintas tendencias de recuperación. Los gremios buceadores y los piscívoros fueron los más afectados. Las variaciones de la abundancia local de los gremios podrían ser atribuidas a fluctuaciones en la disponibilidad de recursos, aunque las variaciones a nivel poblacional no siempre sustentaron esta suposición. Las respuestas específicas de las especies a diferencias en la estructura del habitat y el nomadismo de estas aves también influirían en la generación de los patrones observados.

Abstract:
Waterbirds of Costanera Sur Reserve: Seasonal Changes in Species Composition and in the Abundance of Populations and Guilds. Changes in species composition and variation in the local abundance of guilds and populations of the waterbird community of Costanera Sur Reserve were analyzed from November 1988 to Octoher 1989. An intense drought brought about a remarkable reduction of the flooding Ievel of the ponds during summer. which produced an abrupt decline in the species richness and high qualitative dissimilarity between sampling occasions. The species returned to the Reserve as ponds became filled, influencing very little the comunity composition. Both guilds and populations showed important numerics fluctuations. All species were affected by drought, but they showed different trends of recovery. Divingand piscivorous guilds were the most strongly affected. Variations in the local abundance of guilds could be attributed to fluctuations in the availability of resources, but variations in the abundance of populations sometimes denied this hypothesis Both the species-specific responses to differences in habitat structure and the nomadic behavior of species could be influencing the observed patterns.

Resumen:
Se condujeron estudios de campo y cautividad para evaluar el uso de las banda plásticas de colores en estudios de comportamiento del Varillero Congo (Agelaius ruficapillus) en una colonia reproductiva y en sitios de alimentación vecinos a la misma. En la colonia, las observaciones desde sitios ocultos muestran la utilidad del uso de las banda numeradas para la colección de datos sobre el comportamiento de los indiviudos. En los campos de arroz, si bien los números no se pudieron observar, se pudo delinear la distribución de los miembros marcados en la colonia. Se investigaron en condiciones de laboratorio y jaula, dos métodos de adhesión y dos de tipo de tintas para marcado de las banda.

Abstract:
New data on geographic distribution of 12 species of Argentine birds are given. They come from surveys carried out from 1987 to 1992 in different parts of Argentina.

Abstract:
New data on the status of Buteo albigula in Argentina Patagonia. We list new records of B. albigula in Nahuel Huapi National Park, and neighboring regions (Argentine Patagonia). Data show that the species is more common thas previously thought, perhaps because it is poorly know and hard to observe. B albigula is found in forested areas and its survival is cleary tied to that one of the forest in Argentine Patagonia and elsewhere.

Abstract:
We have found 51 registrations of the Dryocopus galeatus in Argentina, 30 of them unpublished. These show species spreading in Misiones province throughout different environments and political departaments. Several aspects of rarity and ecology of the species are discussed under light of new information gathered, as since few years ago it was con sidered "probably extincted".

Abstract:
First record for Argentina of the Pearled Treerunner (Margarornis squamiger) and new data on the geographic distribution of the Ornate Hawk-Eagle (Spizaetus ornatus), Yellow-headed Caracara (Milvago chimachima), Purplish lay (Cyanocorax cyanomelas), Swallow- Tanager (Tersina viridis) and Blue-naped Chlorophonia (Chlorophonia cyanea) in NW Argentina are given.

Abstract:
Three new data on birds distribution for Santiago del Estero are given: a new locality for Anas discors, a new record for Theristicus caudatus and a concrete locality for Sporophila collaris.

Abstract:
New records from uruguayan birds. Between 1987-1990 I visited 12 times "Termas del Río Dayman" (13 km SE from Salto, Uruguay). I recorded 130 species and give information on 10 species.

Abstract:
New records and biogeographic comments on the avifauna of eastern San Juan Province (Argentina Republic). New data on the subtropical avifauna of the E region of San Juan Province are given. 18 of 35 species mentioned in this paper lack well documented previous records, and tbe information on the remaining 17 is scarce. Comparison of these results with available biogeographic literature allow us to confirm penetration in San Juan of a subtropical ornitogeographic flow, which follows xerophytic wood relics of Mountain and Western Chaco districts. This penetration occurs within a wide transition with Monte scrublands.

Resumen:
Occurrence of Dendrocygna autumnalis in Northwest Rio Grande do Sul, Brazil. The first undoubted record of the species in the State, at 56° 08' W e 28° 46' S, is given, based on visual observation with slide documentation of two flocks, totalling 236 birds, in may 1991.

Abstract:
Brood Parasitism of the Shiny Cowbird, Molothrus bonariensis on Chestnut-Capped Blackbird Agelaius ruficapillus, In Eastern Buenos Aires Province, Information about brood parasitism of the Shiny Cowbird on the Chestnutcapped Blackbird in E Argentina is very scarce. Data of 29 active nests of this blackbird from 3 localities of E Buenos Aires province (Bernal, Hudson and General Lavalle), were studied. Ten of these nests were parasitized (34.5 %), suggesting a considerable incidence of parasitism and adverse effect over the Chestnut-capped Blackbird brood was detected through a lower number of host eggs and chicks in parasitized nests. A revision of available data is presented and results are compared with those from other authors.

Abstract:
The first record ofthe Rufous-tailed Antthrush (Chamaeza ruficauda ruficauda) in Argentina is given, based on a specimen collected at Tobuna, Misiones province.

Abstract:
On May 29,1993,16 individuals of Cattle Egret Bubulcus ibis landed in the deck of a ship in the South Atlantic Ocean, at 290 nautic miles from Malvina Islands and 450 from South Georgia. The birds showed severe reduction of pectoral muscle. Local West-East prevaling winds could have blown the birds from somewhere on the south Argentine coast.

Abstract:
First record of the Wedgetailed Hillstar (Oreotrochilus adela) for Argentina. A new hummingbird species was recorded for the Argentinian avianfauna. The notes were registered in Yavi, (220 07'S, 650 28'W), Jujuy province, between 23 and 26 Jan 1991.

Resumen:
En este trabajo se presentan datos sobre la biología reproductiva del Gavilán Ceniciento (Circus cinereus) en la provincia de Santa Cruz. El estudio fue llevado a cabo desde el 20 sep de 1987 hasta el 5 ene de 1988. Los Gavilanes se hallaban nidificando en forma colonial en un mallín. Los diez nidos encontrados estaban dispersos en un área de 3,5 hectáreasy la distancia promedio con el nido más cercano fue de 46,4 m. La densidad de nidificación fue de un nido cada 0,35 ha. La postura promedio ± DS fue de 3,5 ± 0,91 huevos y el período de incubación en un nido con 5 huevos fue de aprox.28 a 32 días. Un 54 % de los huevos produjeron pichones. La temporada de cría se extendió desde fines de septiembre hastafines de febrero o principios de marzo. Los Gavilanes defendían colectivamente los nidos frente a aves rapaces y ante personas.Un caso de poliginia fue registrado. Las vocalizaciones, despliegues aéreos y características de los pichones son descriptos. Los hábitos reproductivos del Gavilán Ceniciento son en general similares a los de otras especies del género pero difieren de las demás en la existencia de nidificación colonial, defensa colectiva de los nidos y ausencia de agresividad entre los ejemplares de la colonia.

Abstract:
Data on the breeding biology of the Cinereous Harrier (Circus cinereus) in Santa Cruz province, Argentina, are given. The study was conducted from 20 Sep 1987 to 5 Jan 1988. Hamers nested colonially in a marsh dominated by Juncus sp. Ten nests were placed in 3,5 has. Mean distance to the nearest conspecific nest was 46,4 m. Nesting density was l nest per 0,35 ha. Mean clutch size was 3,5 ± 0,91 eggs. Incubation period in one nest with 5 eggs was 28- 32 days. 54 % of the eggs hatched. Breeding period extended from later Sep to later Feb or early Mar. Hamers defended colectively the nests from humans or raptors. One case of polygyny was recorded. Vocalizations, aerial displays and nestling development are described. The breeding biology of the Cinereous Hamer appears to be similar to that of other Circus species except for its colonial nesting habits, colective defences of nests and absence of intraspecific attacks between nesting birds.

Resumen:
Recuento de aves rapaces por carretera en Argentina central. Durante oct 1992 se realizaron conteos en carretera de rapaces a lo largo de 2230 km, en una región central de la Argentina Fueron detectadas 16 (80%) de las 20 especies presentes (incluyendo jotes). La especie más común fué el Chimango Milvago chimango (n=1397), seguida del Gavilán Caracolero Rostrhamus sociabilis (n=191), y del Carancho Polyborus plancus (n=66). La abundancia del Chimango parece estar relacionada positivamente con el nivel de alteración humana del ambiente, alcanzando valores máximos en las afueras de la ciudad de Buenos Aires. La diversidad de rapaces fue máxima en zonas arbustivas y estepas de la Pampa Seca y el N de la Patagonia.

Abstract:
The presence of 8 species are actualized for Formosa province, Argentina, one of which is first record for the country: Basileuterus jlaveolus. First concrete data about Campephilus melanoleucus, Leptopogon amaurocephalus and Cnemotriccus jitscatus, second data about Trogon curucui and fourth data a out Mesembrinibis cayennensis are given for the province. Third concrete data about Campylorhynchus turdinus is given for the country and Crax fasciolata, an endangered species, is confirmed for Río Pilcomayo National Park.

Abstract:
I report here the presence of a new bird species and give data other 6 species distribution at Córdoba Province, Argentina.