Pablo F. Petracci

CONSERVATION STATUS OF THE BUFF-BREASTED SANDPIPER: HISTORIC AND CONTEMPORARY DISTRIBUTION AND ABUNDANCE IN SOUTH AMERICA

Abstract We present historic and contemporary information on the distribution and abundance of Buff-breasted Sandpipers (Tryngites subruficollis) in South America. Historic information was collated from the literature, area ornithologists, and museums, whereas contemporary data were derived from surveys conducted throughout the main wintering range in Argentina, Uruguay, and Brazil during the austral summers of 1999 and 2001. Variable circular plot sampling was used to estimate population densities. During 1999, the highest concentration of Buff-breasted Sandpipers in Argentina was in southern Bahía Samborombón (General Lavalle District) and areas north of Mar Chiquita coastal lagoon. During 2001, the highest concentrations in Brazil were at Ilha da Torotama and Lagoa do Peixe National Park. During 1999 and 2001, the highest concentrations of Buff-breasted Sandpipers in Uruguay were found along three lagoons (Laguna de Rocha, Laguna de Castillos, and Laguna Garzón) bordering the Atlantic Ocean. Population densities (birds/ha) of Buff-breasted Sandpipers were 0.11 (95% C.I. = 0.04–0.31) in Argentina, 1.62 (0.67–3.93) in Brazil, and 1.08 (0.37–3.18) in Uruguay. High turnover rates at survey sites, due to the formation of large, mobile flocks, contributed to moderately large confidence intervals around our population density estimates. Nevertheless, compared with historic accounts of Buff-breasted Sandpipers, our survey data indicate the population size of this species has declined substantially since the late 1800s and contemporary information suggests the species has continued to decline during the past three decades. Buff-breasted Sandpipers were found almost exclusively in pasturelands and appear to depend heavily upon intensive grazing by livestock, which maintain suitable short grass conditions. We discuss the need for protection of critical areas and proper range management to ensure appropriate habitat remains available for the species, and provide suggestions for future research needs.

Distribution and Abundance of Non-Breeding Shorebirds Along the Coasts of the Buenos Aires Province, Argentina

Abstract The coast of the Buenos Aires province, Argentina, includes a remarkable diversity of habitats and is used by more than fifteen Nearctic shorebird species during the austral summer months. We evaluated non-breeding shorebird distribution and abundance patterns along the Buenos Aires coastal zone and determined shorebird use of different coastal landscapes. Surveys were conducted in December 2000, and January and February 2001, using line-transect methods. The data were classified based on five previously defined coastal landscapes. Fifty four localities were surveyed covering 93 kilometers of coastline. A total of 44 waterbird species corresponding to 13 families were recorded. Shorebirds (Scolopacidae, Charadriidae, Haematopodidae and Recurvirostridae) accounted for approximately 45% of recorded waterbirds, including 14 nearctic species. Shorebird species recorded per locality varied from one to eleven, with 61% of the localities having one to four species. The most common were the American Oystercatcher (Haematopus palliatus), White-rumped Sandpiper (Calidris fuscicollis), Two-banded Plover (Charadrius falklandicus), American Golden-Plover (Pluvialis dominica) and the Sanderling (Calidris alba). Shorebird species richness and abundance varied significantly among coastal landscapes, with the highest values recorded in estuarine saltmarshes of Bahía Samborombón and Bahía Blanca. Among marine landscapes, the highest abundance and number of species were recorded in sandy beaches with “restinga” patches. This study confirms that shorebirds are an important component of the birdlife in the Buenos Aires coastal zone during the austral summer months, and that their distribution is not homogeneous along the coast, with species richness and abundances varying among localities depending on coastal landscapes.

Diet of Sanderling in Buenos Aires Province, Argentina

Abstract The diet of the Sanderling (Calidris alba) was studied using 105 droppings, 34 pellets and direct observations of feeding behavior. This study was carried out during the non-reproductive seasons of 1996 to 2000 in Monte Hermoso, SW of Buenos Aires, Argentina. A total of eleven prey items were identified, with beetles (Coleoptera), Mussels (Brachydontes rodriguezi), clams (Corbula sp.), amphipods (Corophium sp.) and Diptera being the most frequent. The consumption of polychaetes, algae, ants and small fish was also recorded. Sanderlings followed foraging American Oystercatchers (Haematopus palliatus) and cleaned out the valves of mussels and clams (Mesodesma mactroides) left by them. Mussels and beetles were the most constant and dominant prey during the study period. The association of Sanderlings with sandy coasts with rocky patches or restingas is probably due to the rich and diverse invertebrate communities present in this kind of environment, which allow birds to change feeding techniques between different substrates.

Anthropogenic Nesting Sites Allow Urban Breeding in Burrowing Parrots Cyanoliseus patagonus

Summary. How birds adapt to urban life is a key question in evolutionary and conservation biology since urbanisation is one of the major causes of habitat loss worldwide. Some species are able to deal with these anthropogenic changes but a shortage of nesting sites may preclude them from breeding in cities. We conducted a baseline survey of the cliff-nesting burrowing parrot Cyanoliseus patagonus around Bahía Blanca (Argentina), estimating a minimum total of 1,361 pairs breeding at 24 sites (colonies) in 2013. The species showed facultative colonial behaviour, colony size varying between 1 and 300 pairs. Most colonies (68%) and pairs (74%) occupied human-made substrates, mostly quarries but also water wells. Colony size was strongly correlated to the extent of both natural and anthropogenic nesting substrates, suggesting an ideal free distribution of pairs according to the availability of nesting resources. Anthropogenic substrates have certainly allowed population expansion in what is a rather flat landscape with a shortage of cliffs and ravines, as well as urban breeding by a large part (61%) of the surveyed population. This is currently one of the largest populations of burrowing parrots, a previously abundant species that is progressively threatened by persecution and nest poaching for the international pet trade.

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

Fil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Nacional Patagonico; Argentina