Abundance and diversity of waterbirds in a marine wetland of Golfo San jorge, Argentina

Se estudiaron la diversidad y la abundancia de aves acuáticas que utilizaron los ambientes intermareales y aguas someras de la caleta Malaspina, Golfo San Jorge, Chubut, mediante conteos semanales durante la primavera de 2000. Para esto se ubicaron siete estaciones de muestreo en ambientes intermareales representativos de la heterogeneidad ambiental presente a lo largo de la línea de costa de la caleta. El ensamble estuvo compuesto por 31 especies y mostró una alta diversidad específica de aves acuáticas. La composición del ensamble mostró un núcleo de especies dominantes y muchas especies con abundancias menores, y varió a lo largo del estudio, debido principalmente a la disminución en abundancia de la Gaviota Cocinera (<i>Larus dominicanus</i>) y a la llegada de los primeros pulsos migratorios del Playerito Rabadilla Blanca (<i>Calidris fuscicollis</i>). La zona norte del Golfo San Jorge, incluida la caleta Malaspina, ha sido propuesta para la creación de una futura área marina protegida. La información obtenida en este trabajo contribuirá para generar pautas de manejo eficientes para la conservación de éste y otros humedales marinos patagónicos.We studied the diversity and abundance of waterbirds using the intertidals and shallow waters of Malaspina inlet, San Jorge Gulf, Chubut, by means of weekly counts during the spring of 2000. We selected seven survey stations along the coastline of the inlet, representing the habitat heterogeneity of the whole wetland. The waterbird assemblage showed a total of 31 species and exhibited high species diversity, with a core of dominant species and several others that showed low abundance. The composition of the assemblage varied throughout the study, mainly due to the decrease in the number of Kelp Gull (Larus dominacus) and the increase in numbers of the migratory White-rumped Sandpiper (Calidris fuscicollis). The northern sector of San Jorge Gulf, including the Malaspina inlet, has been included in a proposal for a new marine protected area. The information obtained in this study will contribute to the development of management guidelines aimed at the conservation of this and other marine wetlands of Patagonia

Abundance and diversity of waterbirds in a marine wetland of Golfo San jorge, Argentina

Se estudiaron la diversidad y la abundancia de aves acuáticas que utilizaron los ambientes intermareales y aguas someras de la caleta Malaspina, Golfo San Jorge, Chubut, mediante conteos semanales durante la primavera de 2000. Para esto se ubicaron siete estaciones de muestreo en ambientes intermareales representativos de la heterogeneidad ambiental presente a lo largo de la línea de costa de la caleta. El ensamble estuvo compuesto por 31 especies y mostró una alta diversidad específica de aves acuáticas. La composición del ensamble mostró un núcleo de especies dominantes y muchas especies con abundancias menores, y varió a lo largo del estudio, debido principalmente a la disminución en abundancia de la Gaviota Cocinera (<i>Larus dominicanus</i>) y a la llegada de los primeros pulsos migratorios del Playerito Rabadilla Blanca (<i>Calidris fuscicollis</i>). La zona norte del Golfo San Jorge, incluida la caleta Malaspina, ha sido propuesta para la creación de una futura área marina protegida. La información obtenida en este trabajo contribuirá para generar pautas de manejo eficientes para la conservación de éste y otros humedales marinos patagónicos.We studied the diversity and abundance of waterbirds using the intertidals and shallow waters of Malaspina inlet, San Jorge Gulf, Chubut, by means of weekly counts during the spring of 2000. We selected seven survey stations along the coastline of the inlet, representing the habitat heterogeneity of the whole wetland. The waterbird assemblage showed a total of 31 species and exhibited high species diversity, with a core of dominant species and several others that showed low abundance. The composition of the assemblage varied throughout the study, mainly due to the decrease in the number of Kelp Gull (Larus dominacus) and the increase in numbers of the migratory White-rumped Sandpiper (Calidris fuscicollis). The northern sector of San Jorge Gulf, including the Malaspina inlet, has been included in a proposal for a new marine protected area. The information obtained in this study will contribute to the development of management guidelines aimed at the conservation of this and other marine wetlands of Patagonia

Abundance and diversity of waterbirds in a marine wetland of Golfo San Jorge, Argentina

Se estudiaron la diversidad y la abundancia de aves acuáticas que utilizaron los ambientes intermareales y aguas someras de la caleta Malaspina, Golfo San Jorge, Chubut, mediante conteos semanales durante la primavera de 2000. Para esto se ubicaron siete estaciones de muestreo en ambientes intermareales representativos de la heterogeneidad ambiental presente a lo largo de la línea de costa de la caleta. El ensamble estuvo compuesto por 31 especies y mostró una alta diversidad específica de aves acuáticas. La composición del ensamble mostró un núcleo de especies dominantes y muchas especies con abundancias menores, y varió a lo largo del estudio, debido principalmente a la disminución en abundancia de la Gaviota Cocinera (Larus dominicanus) y a la llegada de los primeros pulsos migratorios del Playerito Rabadilla Blanca (Calidris fuscicollis). La zona norte del Golfo San Jorge, incluida la caleta Malaspina, ha sido propuesta para la creación de una futura área marina protegida. La información obtenida en este trabajo contribuirá para generar pautas de manejo eficientes para la conservación de éste y otros humedales marinos patagónicos.We studied the diversity and abundance of waterbirds using the intertidals and shallow waters of Malaspina inlet, San Jorge Gulf, Chubut, by means of weekly counts during the spring of 2000. We selected seven survey stations along the coastline of the inlet, representing the habitat heterogeneity of the whole wetland. The waterbird assemblage showed a total of 31 species and exhibited high species diversity, with a core of dominant species and several others that showed low abundance. The composition of the assemblage varied throughout the study, mainly due to the decrease in the number of Kelp Gull (Larus dominacus) and the increase in numbers of the migratory White-rumped Sandpiper (Calidris fuscicollis). The northern sector of San Jorge Gulf, including the Malaspina inlet, has been included in a proposal for a new marine protected area. The information obtained in this study will contribute to the development of management guidelines aimed at the conservation of this and other marine wetlands of Patagonia.Facultad de Ciencias Naturales y Muse

Variation in the size of eggs of Kelp Gulls (Larus dominicanus) at two colonies in Patagonia, Argentina

Although several studies have reported basic information about the size of Kelp Gull (Larus dominicarius) eggs, no attention has been paid to the comparison of patterns of intra-clutch variation at different breeding sites. Here, the variation in egg size of Kelp Gulls at two colonies from Patagonia, Argentina, was analyzed. The objectives were to characterize egg size variation in Kelp Gulls breeding at a recently established colony in Punta Loma that primarily relies on natural prey; and to evaluate if patterns of intra-clutch variation in that colony differ from those at Vernaci Sudoeste Island, a larger and well-established colony with access to supplementary food in the form of fishery waste. In two-egg clutches, first-eggs were larger than second-eggs. Neither average egg size nor intra-clutch patterns differed between study sites. Also, in two-egg clutches, egg size decreased as date of laying increased, probably due to younger birds laying smaller eggs later in the season. The pattern of intra-clutch variation in three-egg clutches differed between sites. Three-egg clutches at Vernaci Sudoeste Island presented similar sizes for first- and second-eggs and these were larger than third-eggs. This pattern contrasted with the steady decrease in relation to laying order that was observed at Punta Loma. Also, second-and third-eggs from Vernaci Sudoeste Island were larger than corresponding eggs from Punta Loma. Our data suggest that differences in egg size between colonies could be the consequence of enhanced food availability at Vernaci Sudoeste Island in the form of discards generated by trawl fisheries. Future studies to evaluate age of birds and inter-annual environmental stochasticity are needed to elucidate the effect of these factors on egg size variationFil: Svagelj, Walter Sergio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Lisnizer, Nora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Garcia Borboroglu, Jorge Pablo. 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

GENETICS AND DEMOGRAPHY OF KELP GULLS IN PATAGONIA

The Kelp Gull (Larus dominicanus), a common seabird in coastal Patagonia, has recently increased in overall abundance and distribution, creating some concerns for the protection and conservation of other native, threatened species. We combined genetic and demographic data of four large Kelp Gull colonies distributed along 1800 km of the northern Patagonian coast of Argentina to further understand patterns of population growth and migration of the species. DNA analysis of variable intron sequences of two separate genes (myelin proteolipid protein, β-fibrinogen) revealed similar intra-colony levels of DNA sequence diversity. Pairwise FST comparisons revealed significant differentiation of the northernmost colony, Islote La Pastosa, from the two southern colonies, Punta Tombo and Isla Vernaci Sudoeste (p &lt; 0.05). Indirect estimates of gene flow suggest significant mixing among colonies (Nm &gt; 6). Demographic estimates revealed that Islote La Pastosa showed an increase in the number of breeding individuals over time (λ = 1.075), representing an area of potential population expansion. This is consistent with previous studies that have suggested that the demographic connectivity among Kelp Gull colonies in Patagonia may follow a source-sink dynamics, where growth rates of growing colonies are fuelled by the immigration of individuals from nearby colonies. The observed pattern also reflects the overall expansion of the species in the Patagonian region. This study suggests that proper management strategies for the Kelp Gull should take into account the genetic and demographic dynamics of this species

Apparent selective advantage of leucism in a coastal population of Southern caracaras (Falconidae)

ABSTRACT Background: Southern caracaras are medium-sized raptors with a large range stretching to the southern tip of South America. An aberrant, leucistic plumage is found commonly along the coast of Chubut Province (Patagonia, Argentina). Leucistic birds do not produce dark melanin in their feathers. However, they are not albinos because their eyes are not red. No genetic studies of caracara plumages are known. Hypothesis: The high frequency of leucistic birds in Chubut Province arises because of natural selection. Methods: Map the distribution of leucistic individuals relative to normal individuals. Combine a variety of anecdotal natural history observations, collected over 20 years, into a logical inference. Observations: Leucistic caracaras were found only along a 250-km stretch of rocky oceanic islands and continental outcrops with large seabird colonies in Chubut Province. In the rest of their range, Southern caracaras have dark plumage. Where they do occur, leucistic birds are frequent and co-occur with dark-plumaged birds. Intermediate individuals, presumabl

Trophic niche expansion during the non‑breeding season in kelp gulls of known breeding colony

Year-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

Trophic niche variation throughout the year in the opportunistic Kelp Gull at different trophic scenarios in Patagonia, Argentina

Changes in foraging strategies throughout the year are key determinants of seabird population dynamics. However, due to seabird post-breeding dispersal, year-round trophic ecology studies rarely focus on individuals from known colonies. Using stable isotope analysis (δ15N, δ13C) of blood and primary feathers, we tested during 2012 the trophic niche variation throughout the year in Kelp Gulls Larus dominicanus from three colonies in Patagonia, Argentina, located in areas with different availability of anthropogenic food subsidies. Isotopic niche width, measured using multivariate ellipse-based metrics, was wider at all colonies during the non-breeding season, suggesting that during this period gulls forage on a greater variety of food sources possibly related to post-breeding dispersal, seasonal changes in food resources, and/or the relaxation of central place foraging. Individuals from the colony with yearround availability of fisheries discards (Isla Vernaci) presented the lower isotopic niche width year-round compared to those from the other two colonies, one with discards only available during the breeding season (Punta Tombo) and the other with only open-air refuse dumps available all year-round (Punta León). At Isla Vernaci, an abrupt expansion in niche width occurred later in the non-breeding season, after the start of a fisheries moratorium, suggesting that Kelp Gulls remained in nearby areas and partly associated to trawl fisheries between breeding events. Preliminary diet results indicate that most studied individuals from Isla Vernaci were feeding on demersal prey, only available from fisheries discards as Kelp Gulls are surface feeders. These results suggest that the availability of discards can greatly influence Kelp Gull foraging strategies and non-breeding movements, and that changes in niche metrics can be context dependent. Future studies should complement the assessment of niche variability with studies of diet composition throughout the year.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: Gatto, Alejandro Javier. 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; Argentina3rd World Seabird ConferenceVictoriaCanadáWorld Seabird Unio

Diving behavior and foraging areas of the neotropic cormorant at a marine colony in Patagonia, Argentina

Volume: 116Start Page: 83End Page: 8