Patrones temporales en la abundancia y uso de residuos por Gaviotas cocineras (Larus dominicanus) en un basural urbano y pesquero de la costa norte de Patagonia, Argentina

We quantified the use by Kelp Gulls (Larus dominicanus) of urban and fishery waste sites at Puerto Madryn, Argentina, during 1996 and 1997. Kelp Gulls were present at all monthly counts made at both waste sites throughout the two years of the study. Total numbers of gulls in each month were high and variable, with a mean of 4724 and 4612 individuals in 1996 and 1997, respectively. The mean number of gulls at the fishery waste site was significantly larger than at the urban waste site (3767 vs 901). Adult Kelp Gulls were significantly more abundant than non-adult gulls at every count at both the urban and fishery waste sites (mean = 811 vs 91 and 3147 vs 628, respectively). Among the younger age classes, individuals in their third year were the least abundant. The proportion of adults with respect to total gulls present was high during all visits to both sites, although it showed a slight decrease in the fishery waste site during the breeding season. During the breeding season, the number of gulls varied significantly throughout the day at both sites while, during the non-breeding season, numbers varied significantly only in the urban waste site. The Puerto Madryn fishery waste site constitutes a more attractive food source than the urban waste site probably due to the higher quality and quantity of discarded food. The use of waste sites at Puerto Madryn may be enhancing gull breeding success and individual survival during the winter, particularly of young birds. Potential conflicts due to Kelp Gull use of waste sites and the effects on their populations could be minimized by adequate urban and fish waste managementCuantificamos el uso por la Gaviota cocinera (Larus dominicanus) de los basurales urbanos y pesqueros en Puerto Madryn, Argentina, durante 1996 y 1997. La Gaviota cocinera estuvo presente en todos los censos mensuales efectuados en ambos basurales durante los dos años. Los números totales de gaviotas en cada mes fueron altos y variables, con una media de 4724 y 4612 individuos en 1996 y 1997, respectivamente. El número medio de gaviotas en el basural pesquero fue significativamente mayor que en el basural urbano (3767 vs 901). En todos los conteos en los basurales pesquero y urbano, las gaviotas adultas fueron significativamente más abundantes que las no adultas (media = 811 vs 91 y 3147 vs 628, respectivamente). Entre las clases de edad más jóvenes, los individuos del tercer año fueron los menos abundantes. La proporción de adultos respecto al total de gaviotas presentes fue alta en todas las visitas a ambos basurales, aunque mostró una leve disminución en el basural pesquero durante la temporada reproductiva. Durante la temporada reproductiva, el número de gaviotas varió significativamente a lo largo del día en ambos basurales, mientras que en la temporada no reproductiva los números variaron significativamente solo en el basural urbano. El basural pesquero de Puerto Madryn constituye una fuente de alimento más atractiva que el basural urbano, probablemente debido a la mayor cantidad y calidad de los residuos depositados. El uso de los basurales en Puerto Madryn podría estar favoreciendo el éxito reproductivo de las gaviotas y la supervivencia individual durante el invierno, particularmente de aves jóvenes. Los conflictos potenciales resultantes del uso por la Gaviota cocinera de los basurales y los efectos sobre sus poblaciones podrían ser minimizados con un adecuado manejo de los residuos urbanos y pesquerosFil: Giaccardi, Micel. Secretaría de Turismo y Áreas Protegidas; ArgentinaFil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Wildlife Conservation Society; Estados Unido

Population and conservation status of terns and skuas breeding in coastal argentina

Tres especies de gaviotines y dos de escúas se reproducen en el litoral marítimo argentino. El Gaviotín Sudamericano (<i>Sterna hirundinacea</i>), el Gaviotín Pico Amarillo (<i>Thalasseus sandvicensis eurygnatha</i>) y el Gaviotín Real (<i>Thalasseus maximus</i>) difieren en cuanto a su distribución y abundancia. En los últimos 15 años se han identificado 40 sitios donde se reprodujo el Gaviotín Sudamericano, mientras que fueron reportados 18 y 12 sitios para el Gaviotín Pico Amarillo y para el Gaviotín Real, respectivamente. Los frecuentes cambios entre años en la elección de sitios donde reproducirse han dificultado hasta la fecha la obtención de una buena estimación de su tamaño poblacional total en el litoral marítimo argentino. Por su parte, se ha registrado desde principios de la década de 1990 un total de 31 localidades de reproducción de la Escúa Parda (<i>Catharacta antarctica</i>) y 15 de la Escúa Común (<i>Catharacta chilensis</i>). Ambas especies muestran un tamaño poblacional total relativamente bajo. Los gaviotines y las escúas mencionados se encuentran entre las aves marinas menos estudiadas de Argentina, desconociéndose para las escúas incluso aspectos básicos de su biología reproductiva. En este trabajo se actualiza información sobre la distribución y abundancia de estas especies de gaviotines y escúas, sintetizando los datos existentes sobre estimaciones poblacionales, tanto publicados como inéditos. Para los gaviotines se presenta también una revisión sobre aspectos de su biología (relativos al ciclo reproductivo, ecología alimentaria y requerimientos de hábitat) que pueden ser de utilidad para la elaboración de programas de monitoreo, planes de acción y estrategias regionales de conservación. Finalmente, se presenta una evaluación del estado actual de conservación y la problemática de manejo y se elabora una lista de recomendaciones.Three tern and two skua species breed along coastal Argentina. The South American Tern (<i>Sterna hirundinacea</i>), the Cayenne Tern (<i>Thalasseus sandvicensis eurygnatha</i>) and the Royal Tern (<i>Thalasseus maximus</i>) differ in their distribution and abundance. During the last 15 years, 40 South American Tern breeding sites were identified, while 18 and 12 breeding sites have been reported for the Cayenne Tern and the Royal Tern, respectively. The frequent changes in breeding location between years have hindered the proper estimation of their total breeding population for the Argentine coast so far. Since the early 1990 decade, a total of 31 and 15 breeding sites of the Brown Skua (<i>Catharacta antarctica</i>) and the Chilean Skua (<i>Catharacta chilensis</i>), respectively, have been reported. Both skuas show a relatively small total breeding population. Terns and skuas are among the least studied seabirds in Argentina, and even basic aspects of the breeding biology of skuas are still unknown. The distribution and abundance of these terns and skuas is updated, and information on population estimates, both published and unpublished, is reviewed. In addition, aspects of the biology of terns (such as those related to their breeding cycles, feeding ecology and habitat requirements), which could be useful for the development of monitoring programs, action plans and regional conservation strategies, are reviewed. Finally, an evaluation of the current conservation status and management issues and a list of recommendations are presented

Marine protected areas, spatial scales, and governance: implications for the conservation of breeding seabirds

As in many regions worldwide, seabird colonies in Argentina are important conservation targets of marine protected areas (MPAs). Seabirds are wide ranging, often crossing jurisdictional boundaries during foraging. Using a recently designated MPA as a case study, this article discusses the challenges of protecting breeding seabirds given their spatial requirements and use of different jurisdictions. Seabirds breeding at the MPA have distinct foraging strategies. Rock Shags and Olrog's Gulls forage inshore within the MPA. Imperial Cormorants, Magellanic Penguins, and Southern Giant Petrels, in contrast, often feed beyond the MPA's jurisdiction, traveling into provincial, federal, or international waters where they can be affected by fisheries and oil development. This indicates the need of management actions beyond MPA boundaries. The large scale and connectivity of marine ecosystems and the variety of economic pressures require the participation of stakeholders and several government agencies in conservation issues, and thus integrated coastal management and marine spatial planning appear as options to complement the use of MPAs. Although MPAs are a valuable tool to conserve breeding seabirds, increased efforts are needed to design new governance structures and complementary strategies for spatial protection so as to deal with the biological, social, and political complexities of marine systems.Fil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Wildlife Conservation Society; Argentin

Seasonal decline in breeding performance of the Kelp Gull Larus dominicanus

The effects of timing of breeding on reproductive parameters of Kelp Gulls Larus dominicanus were studied in Patagonia, Argentina, during 1998 and 1999. Yearly and spatial variation in the study were assessed by sampling nests during two field seasons and in different areas within the colony, and accounted for variation with respect to breeding synchrony and breeding density. In both years and in three study areas, individuals laying earlier had higher hatching success, a larger number of chicks fledged, heavier chicks at one month and higher breeding success. Significant variation between study areas within the colony and between years was observed only for breeding success and number of chicks fledged. No effects of breeding synchrony on breeding parameters were detected. Timing of breeding, independent of study year and area, had no effect on either clutch size or egg size. Our results document for the first time the seasonal decline in breeding performance in the Kelp Gull, a species widely distributed in the southern hemisphere.Fil: Garcia Borboroglu, Jorge Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Moreno, Juan. Consejo Superior de Investigaciones Científicas; EspañaFil: Potti Sánchez, Jaime. Consejo Superior de Investigaciones Científicas; Españ

Urban and Fishery Waste Tips As Food Sources for Birds in Northern Coastal Patagonia, Argentina

Basurales urbanos y pesqueros como fuentes de alimento para aves en las costas del norte de Patagonia, Argentina. – Los basurales son importantes fuentes de alimento para un gran número de especies de aves en todo el mundo, particularmente especies oportunistas y carroñeras. Efectuamos un relevamiento regional de basurales urbanos y pesqueros en la costa norte de Patagonia para (1) identificar las especies de aves que los utilizan, (2) determinar variaciones estacionales en la presencia y abundancia, y (3) evaluar diferencias en el uso entre localidades. Durante 1996, relevamos 17 basurales urbanos y pesqueros en las costas de las Provincias de Río Negro y Chubut, Argentina. Se efectuaron cuatro visitas a cada basural, una en cada estación del año. Se observaron aves aprovechando los residuos en la mayoría de los basurales visitados. Se identificaron once especies. La Gaviota Cocinera (Larus dominicanus) fue la especie más frecuentemente registrada, estando presente en el 82–88% de los basurales muestreados, en números que variaron dependiendo del sitio y la estación, y mostrando un máximo de 7300 individuos durante el conteo de verano. En contraste, las otras especies de aves fueron observadas menos regularmente y, de estas, sólo la Paloma Doméstica (Columba livia) y el Chimango (Milvago chimango) fueron registrados en números importantes en algunas localidades. La Gaviota Cocinera fue también más abundante en los basurales pesqueros y, en todas las estaciones, el número de adultos fue significativamente mayor que el de las clases de edad más jóvenes. El número de Gaviotas Cocineras presente en los basurales se correlacionó positivamente con el tamaño de los asentamientos humanos en todas las estaciones, salvo la primavera. Las diferencias en el patrón de presencia y abundancia en los basurales entre las especies podrían estar relacionadas con su distribución, tamaño poblacional, y ecología alimentaria.Waste tips constitute important food sources widely utilized by a large number of bird species worldwide, particularly by opportunistic and scavenging species. We conducted a regional survey of urban and fishery waste tips in northern coastal Patagonia to (1) identify bird species that use waste tips, (2) determine seasonal changes in occurrence and abundance, and (3) assess differences in use between locations. During 1996, we surveyed 17 urban and fishery waste tips along the coasts of the provinces of Río Negro and Chubut, Argentina. Four visits were made to each waste tip, once in each of the four seasons. Birds were observed taking advantage of waste at most of the visited tips. Eleven species were identified. The Kelp Gull (Larus dominicanus) was the most frequently recorded species, being present at 82–88% of the tips sampled, with numbers that varied depending on the site and season and showing a maximum of 7300 individuals during the summer count. In contrast, the other bird species were observed less regularly and, of these, only the Rock Dove (Columba livia) and the Chimango (Milvago chimango) were recorded in significant numbers at some of the sites. Kelp Gulls were also more abundant at fishery waste tips and the number of adults was significantly larger than that of younger age-classes in all seasons. Number of Kelp Gulls present at the tips was significantly correlated with the size of human settlements at all seasons except spring. Differences between species in the patterns of occurrence and abundance at waste tips may be related to their distribution, population size and feeding ecology.Fil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Giaccardi, Maricel. Gobierno de la Provincia de Chubut. Dirección de Conservación de Áreas Naturales; Argentin

Current status of the threatened Olrog's Gull Larus atlanticus: global population, breeding distribution and threats

Olrog's Gull Larus atlanticus breeds only in Argentina and is currently categorized as Vulnerable. Knowledge of the location of colonies and an updated understanding of human activities that may impact their breeding populations are crucial to the development of adequate conservation and management actions. In this paper we update the breeding distribution and abundance of Olrog's Gull, using information from three aerial surveys (2004, 2007 and 2009) in its main breeding area, Buenos Aires Province, complemented by additional nest counts in southern Chubut Province, covering its entire breeding range. We also provide an updated and more detailed account of threats faced by Olrog's Gulls at their nesting grounds, and summarise progress made towards their protection. The number of breeding sites was 7-12 per year, with locations differing among years. Five previously unrecorded breeding locations were identified. Colony size ranged from 5 to 3,540 breeding pairs, with the total breeding population 4,860-7,790 pairs, 98% of which nest in southern Buenos Aires Province. The main threats faced by breeding Olrog's Gulls include coastal development, pollution, sport fishing and unregulated tourism and recreational activities. Recent strengthening of the protected area system in Argentina has resulted in all known breeding sites, with the exception of Isla Brightman, falling within protected areas. We need comprehensive, simultaneous surveys to track global population trends. Despite enhanced protection of Olrog's Gull breeding populations, efforts are still needed to ensure that guidelines for their protection are included in management plans and that these are implemented effectively.Facultad de Ciencias Naturales y Muse

Trophic spectrum of kelp gulls <i>Larus dominicanus</i> at three protected areas in Chubut, Argentina

La Gaviota Cocinera (<i>Larus dominicanus</i>) es una especie abundante y de amplia distribución en Argentina. Aunque se han analizado los patrones espaciales y temporales de la dieta durante la temporada reproductiva en el litoral de Chubut, el listado de las especies consumidas en cada localidad no ha sido aún reportado. Se presenta el espectro trófico de la Gaviota Cocinera en tres áreas protegidas durante los ciclos reproductivos de 1994 y 1995. El análisis se efectuó sobre la base de 1331 y 1515 egagrópilas durante 1994 y 1995, respectivamente. La dieta de la Gaviota Cocinera presentó un total de presas de al menos 38 especies diferentes. Estas incluye- ron al menos 8 especies de peces, 11 de crustáceos, 6 de pelecípodos, 10 de gasterópodos y 3 de poliquetos. A estas se agregaron un número de especies no identificadas de octópodos, decápodos, equinoideos, asteroideos, aves e insectos. Aunque algunas presas mostraron una frecuencia de ocurrencia relativamente importante, la mayoría presentaron frecuencias inferiores al 5%. La diversidad observada en la dieta de la Gaviota Cocinera en las tres localidades confirma que es una especie generalista y oportunista.The Kelp Gull (<i>Larus dominicanus</i>) is an abundant and widely distributed species in Argentina. Although spatial and temporal patterns in the diet during the breeding season in coastal Chubut have been analyzed, the list of prey species consumed at each location has not yet been reported. The prey trophic spectrum of the Kelp Gull at three protected areas during the 1994 and 1995 breeding seasons is presented. The analysis was based on 1331 and 1515 pellets during 1994 and 1995, respectively. Kelp Gull diet presented at least 38 different prey species. These included at least 8 fish species, 11 crustaceans, 6 pelecipods, 10 gasteropods, and 3 polychaetes, added to a number of unidentified species of octopods, decapods, echinoids, asteroids, birds and insects. Although some prey showed a relatively important frequency of occurrence, most prey showed frequencies lower than 5%. The observed diversity in the diet of the Kelp Gull at the three analyzed locations confirms it is a generalist and opportunist species

An updatc of the breeding distribution, population status and conservation of the Olrog' s gull (<i>Larus allanticus</i> )

En el presente trabajo se actualiza la distribución reproductiva, el tamaño poblacional y el estado de conservación de la gaviota de Olrog (<i>Larus atlanticus</i> ). La distribución de nidificación conocida se amplía 140 km hacia el norte y 640 km hacia el sur, con colonias en la Isla Brightman, provincia de Buenos Aires, e Islas Vernaci, provincia del Chubut, respectivamente. Se citan 5 colonias de reproducción, todas ellas en islas, 3 de las cuales son descriptas por primera vez. Se estima que el total poblacional de esta especie es de l220± 127 parejas. En base a los resultados obtenidos, se exponen las implicancias para la conservación de esta especie.An updatc of the breeding distribution, population status and conservation of the Olrog' s gull (<i>Larus allanticus</i> ). In this paper we update the breeding distribution, population size and conservation status of the Olrog's gull (Larus allanticus). Its known breeding distribution is extended 140 km north and 640 km south. with colonies at Isla Brightman, Buenos Aires province, and Islas Vernaci. Chubut province respectively. We report 5 breeding colonies, all of them located on islands. and three of which are described for the first time. We estirnate the total population size in 1220 ± 127 breeding pairs. We discuss the implications of the survey results for the conservation of this species

New breeding location for the olrog`s gull <i>Larus atlanticus</i> in the province of Buenos Aires, Argentina

Se presenta información sobre una nueva colonia de Gaviota de Olrog (<i>Larus atlanticus</i>), una especie endémica de la Argentina y considerada internacionalmente como vulnerable. La colonia, visitada el 16 de noviembre de 2001, estaba localizada en un islote ubicado en el Canal Ancla (38°56'S, 62°11'O), unos 13 km al sudoeste de la ciudad de Punta Alta. Los nidos se hallaban distribuidos en cuatro grupos, de entre 17 y 238 nidos, totalizando 340 nidos activos. La colonia de Gaviota de Olrog se encontraba rodeada por nidos de Gaviota Cocinera (<i>Larus dominicanus</i>). La Gaviota de Olrog no se reprodujo en este islote en el año 1995. Debido a que esta especie puede cambiar de sitio de reproducción entre temporadas, futuros trabajos deberían evaluar su dinámica espacio-temporal de uso del hábitat.We present information on a new colony of Olrog`s Gull <i>Larus atlanticus</i>, endemic to Argentina and internationally considered as vulnerable. The colony, visited on November 16 2001, was on an islet located in the Canal Ancla (38°56'S, 62°11'O), 13 km southeast from Punta Alta. Nests were distributed in four groups of between 17-238 nests, add- ing to a total of 340 active nests. The Olrog?s Gull colony was located within a colony of Kelp Gulls (Larus dominicanus). Olrog`s Gulls did not breed in this islet during 1995. As this species may change colony sites between breeding seasons, future work should evaluate their spatial and temporal patterns of habitat use

Temporal patterns in the diet and food partitioning in Imperial Cormorants (Phalacrocorax atriceps) and Rock Shags (P. magellanicus) breeding at Bahía Bustamante, Argentina

We studied the diet of Imperial Cormorants (Phalacrocorax atriceps) and Rock Shags (P.magellanicus) at Bahý´a Bustamante, Argentina, between 1992 and 1994. We analyzed pellet casts (1887 from Imperial Cormorants and 799 from Rock Shags) and regurgitations of stomach contents (260 from Imperial Cormorants and 24 from Rock Shags). Imperial Cormorants and Rock Shags fed on at least 22 and 21 different types of prey, respectively. The main prey species during all study years were fish: Engraulis anchoita for Imperial Cormorants and Patagonothen sp. for Rock Shags. For both species, the consumption of the main food categories as estimated by pellet analysis was similar among years. A significant relationship was found between Imperial Cormorant and Rock Shag diets during the three years, while the diet overlap index was relatively high. During all years, Imperial Cormorants consumed a significantly larger proportion of pelagic or demersal fish than did Rock Shags, while Rock Shags consumed benthic fish in a greater proportion than did Imperial Cormorants. Mean maximum diving depth, determined using capillary tube depth gauges, of Imperial Cormorants (24.4 m 6 18.8 SD) was significantly greater but more variable than that of Rock Shags (9.3 m 6 4.1 SD).Fil: Punta, Gabriel. Dirección General de Intereses Marítimos y Pesca Continental, Chubut; ArgentinaFil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina. Wildlife Conservation Society; Estados UnidosFil: Herrera, Gonzalo. Dirección General de Intereses Marítimos y Pesca Continental, Chubut; Argentin