1,721,116 research outputs found
Breeding seabirds of Argentina: Conservation tools for a more integrated and regional approach
No full textFil: Yorio, Pablo Martin. Wildlife Conservation Society; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentin
Marine protected areas, spatial scales, and governance: implications for the conservation of breeding seabirds
Get PDFAs 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
Trophic niche expansion during the non‑breeding season in kelp gulls of known breeding colony
Get PDFYear-round foraging strategies are key determinants of bird population dynamics. However, trophic ecology studies during the non-breeding period rarely focus on individuals from a known breeding colony, precluding links to demographic aspects of the target population or metapopulation. Using stable isotope analysis (δ15N, δ13C) of primary feathers moulted sequentially after breeding, we tested the trophic niche variation during the non-breeding seasons 2010 and 2011 in Kelp Gulls Larus dominicanus from a colony in coastal Patagonia (43º04′S, 64º29′W), Argentina. Isotopic niche position changed gradually from late summer to late autumn/early winter due to a progressive depletion in δ15N. In addition, niche spread showed a progressive expansion in the same study period. This niche expansion was consistent with the observed differences in the among-individual variability in feeding ecology suggested by niche metrics, being lower during the end of breeding compared to the non-breeding period. Low δ13C values of some feathers suggest that this expansion may be in part driven by the utilization of non-marine food resources/habitats by some individuals.Fil: Lisnizer, Nora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentin
Habitat Requirements and Selection by Kelp Gulls (Larus Dominicanus) in Central and Northern Patagonia, Argentina
Get PDFWe analyzed habitat requirements and selection of Kelp Gulls (Larus dominicanus) breeding at 68 colonies along 2,500 km of coastline in Patagonia, Argentina. Kelp Gulls use a wide range of nesting habitats that include areas with shrub, grass, and herbs which provide diff erent degrees of cover; open ground of various substrate types; and slopes of widely diff erent gradients, confi rming the plasticity of the species with respect to habitat recorded elsewhere in the Southern Hemisphere. Eighty percent of the colonies were on islands, the probability of occupation of which increased with distance from mainland and availability of vegetation. Vegetation cover was a key component of nesting habitat for Kelp Gulls in Argentina. Gulls occupied areas with higher cover than random areas; but within vegetated areas, they showed preference for sparser cover that increased visibility and facilitated escape. Kelp Gulls o en nested with other species of seabirds and seals and had a positive association with the Olrog’s Gull (L. atlanticus).Fil: Garcia Borboroglu, Jorge Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina. Wildlife Conservation Society; Estados UnidosFil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina. Wildlife Conservation Society; Estados Unido
Trophic spectrum of Kelp Gulls Larus dominicanus at three protected areas in Chubut, Argentina
Get PDFLa Gaviota Cocinera (Larus dominicanus) 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 incluyeron 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 (Larus dominicanus) 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.Fil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Wildlife Conservation Society; Estados UnidosFil: Bertellotti, Néstor Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentin
New breeding location for the Olrog's Gull Larus atlanticus in the Province of Buenos Aires, Argentina
Get PDFSe presenta información sobre una nueva colonia de Gaviota de Olrog (Larus atlanticus), 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 (Larus dominicanus). 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 Larus atlanticus, 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, adding 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.Fil: Rábano, Daniel. Centro de Estudios Ambientales para la Planificación y el Desarrollo; ArgentinaFil: Garcia Borboroglu, Jorge Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Yorio, Pablo Martin. Wildlife Conservation Society; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentin
Diet specialization of Olrog's Gull Larus atlanticus during the breeding season at Golfo San Jorge, Argentina
Get PDFWe studied the diet of breeding Olrog’s Gulls Larus atlanticus during 1994 at two colonies in Golfo San Jorge, Argentina, through the analysis of 207 regurgitated pellets. The diet at Isla Felipe and Isla Vernaci Sudoeste comprised only a few items (9 vs 7 respectively), of which crabs were the main component. At Isla Felipe, the crabs Cyrtograpsus altimanus and C. angulatus were present in 91.2% and 89.2% of pellets, respectively, while the percentage contribution of each species was 76.1% and 21.7%, respectively. At Isla Vernaci Sudoeste, the figures were similar (96.2% and 80% of pellets, and percentage contributions 79.4% and 19.5%). All other taxa were present in less than 11% of pellets. No significant differences were found between colonies in the number of prey items, prey individuals per pellet, and consumption of crabs. Percentage contribution of crabs differed significantly between stages of the breeding cycle at Isla Felipe but not at Isla Vernaci Sudoeste. At both colonies, the proportion of male C. altimanus in pellets was larger than that of females. The proportion of female C. angulatus in pellets at Isla Vernaci Sudoeste was larger than that of males, but no significant differences were found in the consumption of each sex at Isla Felipe. Mean maximum carapace width of male crabs in pellets was not significantly different from that of females at either Isla Felipe or Isla Vernaci. Our study at Golfo San Jorge confirms that Olrog’s Gull is fairly specialized, feeding mainly on crabs during the breeding season.Fil: Herrera, Gonzalo. Provincia de Chubut. Dirección General de Intereses Marítimos y Pesca Continental; ArgentinaFil: Punta, Gabriel. Provincia de Chubut. Dirección General de Intereses Marítimos y Pesca Continental; ArgentinaFil: Yorio, Pablo Martin. Wildlife Conservation Society; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentin
Habitat and nest site characteristics of Olrog's Gull Larus atlanticus breeding at Bahía San Blas, Argentina
Get PDFOlrog’s Gull Larus atlanticus is a vulnerable species endemic to the Argentine Atlantic coast. We present information on new breeding colonies, update information on known colonies, and describe habitat and nest site characteristics of Olrog’s Gulls breeding at Bahý´a San Blas, southern Buenos Aires Province, Argentina. Information was obtained during the 1998 breeding season. We recorded four colonies on islets, with a total population size of 305 pairs. Colonies were located on open ground, partly bordered by vegetation. The two colonies at Islote Arroyo Jabalý´ Oeste were located more than 150 m from the high tide line, while the two colonies at Banco Nordeste were placed only a few metres from the high tide mark (1–6 m). Most nests were located more than a metre away from low Atriplex patagonica bushes (20–30 cm high) and herbaceous species, although a few nests were a few cm from vegetation. Nests were built on vegetation debris, on low herbaceous vegetation, and on gravel and sand. All nests at the four colonies were built with vegetation debris, mainly Spartina densiflora and some Salicornia sp. Mean external and internal diameters of nests were 40.57 ± 5.14 and 19.71 ± 2.21 cm, respectively. Gulls nested in discrete groups at relatively high densities, which ranged between 0.62 and 1.1 nests/m2. Nest occupation and number of eggs per nest varied among colonies. Kelp Gulls Larus dominicanus were observed nesting in close proximity to all colonies. Further studies are needed to assess habitat partitioning between these two species, particularly considering that they nest in association at all breeding locations in coastal Argentina and that Kelp Gulls have shown an important population increase in recent decades.Fil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Rábano, Daniel. Centro de Estudios Ambientales para la Planificación y el Desarrollo; ArgentinaFil: Friedrich, Pablo. Centro de Estudios Ambientales para la Planificación y el Desarrollo; Argentin
Seabird use of discards and incidental captures at the Argentine hake trawl fishery in the Golfo San Jorge, Argentina
Get PDFWe studied discard use and incidental mortality of seabirds attracted to high-sea trawl vessels operating in the Golfo San Jorge, Argentina, during the height of the fishing season in 2003 and 2004. Fourteen seabird species ate food made available by fishing operations. The most frequent and abundant seabirds (percent occurrence, mean number per haul) were the kelp gull Larus dominicanus (98.9%, 207.0), the black-browed albatross Thalassarche melanophrys (98.9%, 94.2) and the white-chinned petrel Procellaria aequinoctialis (91%, 8.4). Flock sizes for the 3 species var- ied from a few to a maximum of 1600 birds. Total seabird abundance varied significantly between stages of the fishing operation, being higher during discarding and haulback than during towing. Incidental capture of seabirds in nets was recorded in 37% of 89 hauls, with a mean capture rate of 1.2 birds per haul. Species incidentally caught were the great shearwater Puffinus gravis , the imper- ial cormorant Phalacrocorax atriceps and the Magellanic penguin Spheniscus magellanicus , with rates that varied between months and years. Considering the fishery’s fishing effort, the estimated total numbers of birds killed during the study were 2254 great shearwaters (CV = 1.1), 1233 imperial cormorants (CV = 1.1) and 35 Magellanic penguins (CV = 2.4) in 2003, and 311 imperial cormorants (CV = 1.7) and 1516 Magellanic penguins (CV = 1.1) in 2004. Black-browed albatrosses and kelp gulls were also struck by the warp cable while feeding on discards from the surface, and drowned when they were dragged underwater. The results obtained in this study show that the hake trawl fishery operating in the Golfo San Jorge may have a significant effect on some seabird populations through the provision of fishing discards and incidental mortality.Fil: Gonzalez Zevallos, Diego Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia; ArgentinaFil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentin
Intraspecific host selection by kleptoparasitic Kelp Gulls in Patagonia
No full textWe studied kleptoparasitic behavior of Kelp Gulls (Larus dominicanus) feeding on fishery waste at trawl vessels in northern Patagonia, Argentina, through experimental discarding of fish. Intraspecific kleptoparasitism involved gulls of all age-classes and was recorded at all hauls. During experimental discarding, Kelp Gulls attempted to steal fish from other gulls in 23.5% of 1,915 cases. The length of fish handled differed between age-classes, being larger for younger age classes. The size of fish carried by victims of kleptoparasitic attempts was similar between age-classes. On the other hand, adult and sub-adult were more frequently attacked when they carried larger fish, while juveniles were victims of kleptoparasitic attempts independent of the size of the fish carried by them. The lengths of successfully stolen fish were similar between victims of different age-classes. Adult and sub-adult were successfully robbed when they carried larger fish, while juveniles were successfully robbed irregardless of the size of the fish carried by them. Gulls of different age-classes were victims of kleptoparasitic attempts, as expected according to the number of fish handled by each age-classes. However, juveniles were successfully robbed more often than other age-classes. Juveniles lost prey in 83% of kleptoparasitic attempts, while sub-adults and adults lost their fish in 41.0 and 41.5% of cases, respectively. Although selection of juvenile hosts could be more profitable, attack rate on young birds was not higher than expected, suggesting attacks at trawlers are random. This context of high density of potential victims may be advantageous for juveniles compared to other feeding habitats because they are not particularly harassed or displaced by older, foraging gulls. If so, this could contribute to juvenile survival which would greatly increase population size.Fil: Bertellotti, Néstor Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentin
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