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The article discusses a study on the presence of Streptocara formosensis in Chubut steamerduck, Tachyeres leucocephalus, which is endemic to the Patagonian Coast. This is the first record of the parasite in South America and from the Chubut steamerduck. The difference of Streptocara formosensis from other species in the genus is the absence of a collarette in both sexes.

The article discusses a study on the first record of the intermediate host of cystacanths, Pseudocorynosoma constrictum, in central Mexico in 1918. Pseudocorynosoma constrictum is an endoparasite affecting waterfowl species. The study found the presence of this endoparasite in seven species of waterfowl from the region. Its intermediate host was the freshwater amphipod Hyalella azteca.

We documented the breeding distribution and estimated abundance of Chubut Steamerducks Tachyres leucocephalus, a flightless waterbird endemic to a relatively small section of coastline in Patagonia, Argentina. The distribution of Chubut Steamerducks is restricted to approximately 700 km of coast. We counted 1,703 adult steamerducks at a subset of shorelines within their range and estimated 1,841 adults after correcting for visibility for shore-based surveys. To estimate adult densities in unsurveyed areas, we used two different methods of extrapolation, resulting in estimates of 1,587 and 1,832 adults. Combined with numbers from surveyed shorelines, the total breeding population size is estimated to be between 3,428 and 3,673 adults. In addition, we counted 1,899 juvenile steamerducks, which occur in irregular aggregations. The Interjurisdictional Marine Park in San Jorge Gulf contains about 46% of the entire population, which may provide some protection from disturbance and habitat destruction. However, oil pollution, other anthropogenic activities, and invasive species still pose potential threats to the population. [ABSTRACT FROM PUBLISHER]

Although several studies have analysed spatial or temporal variation in the size of eggs in waterfowl (Anseriformes), no study has analysed variation throughout the breeding range of a species. Chubut Steamer Ducks (Tachyeres leucocephalus) are flightless marine waterfowl endemic to a small section of coastline in Patagonia, Argentina. We partitioned and analysed sources of variation in the size of 989 Chubut Steamer Duck eggs, from 175 clutches, obtained during the breeding seasons of 1998 and 2004-08 at 31 islands throughout the range of the species. In relation to other Anseriformes, we found a low level of variation (coefficient of variation = 6.4%) at the species level. Most variation in the size of eggs were within clutches (59.0%) and among clutches (34.5%); variation between islands within geographical areas accounted for only 6.5% of variation, and there was no variation among geographical areas. Variation in size of eggs was not related to year, apparent clutch-size or latitude. The low variation at the species level and the lack of variation in size of eggs between geographical areas could be a consequence of the low genetic diversity and restricted distribution of the species. This study highlights the potential importance of variation in egg-size for understanding ecological processes linked to the natural history of avian species. [ABSTRACT FROM AUTHOR]

We studied nest-site selection of the flightless Chubut Steamer Duck (Tachyeres leucocephalus) along 292km of continental coastline and 59km of island coastline in Patagonia, Argentina, between 2004 and 2006. This area encompasses the main breeding range of the species. Almost all nests were on islands and islets, which ranged in area from 0.5 to 54.4ha and were 0.01–5.6km from the mainland. Nesting sites were within bays and inlets with shallow waters and protected from waves, winds and strong currents. Using logistic regression analyses in an information-theoretic framework to compare habitat characteristics between nesting sites and randomly chosen sites, we found that Chubut Steamer Duck nesting sites were strongly and positively associated with higher proportions of shrub vegetation cover. To a lesser degree, the percentage of silt–clay sediment was also positively associated with nesting sites. Nest-site selection is thought to be associated with concealment from aerial predators and protection from weather. This is the first study of breeding habitat and nest-site selection of Chubut Steamer Ducks, and will contribute to management and habitat conservation for this rare flightless duck through identification of both general and specific habitat features that should be preserved or enhanced. [ABSTRACT FROM AUTHOR]

The article offers information on the observations regarding the distribution and locations of a Cape Gannet Morus capensis in Patagonia, Argentina. It mentions that the Cape Gannet was in a colony of Imperial Cormorants Phalacrocorax atriceps or of Imperial Cormorants and Rock Shags P. magellanicus. It notes the breeding seasons of Cape Gannet and suggests that these species could survive in Argentine waters on anchovy.