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D.E. Blanco

Publications and source records attributed to D.E. Blanco.

2 recordsLinked to original sources

The conservation and population status of the world's waders at the turn of the millennium

Using information from many sources, but especially data collated for the third edition of Wetlands International’s Waterbird Population Estimates, we review the status of the world’s waders in the late 1990s. There are widespread declines in most regions and biotopes caused principally by loss and degradation of wetland (and other) habitats. On different flyways, between 33%and 68% of populations are in decline, compared with only 0% to 29% increasing. Non-migratory, island species have especially poor status, with about half of all island waders being globally threatened with extinction. Of particular conservation concern is the declining environmental status of several key staging areas,which provide energetic ‘spring-boards’ for long-distance migrants. The degradation of these areas compromises the status of many migrant waders. The rapid collapse of populations, forced below threshold levels, has been predicted theoretically, and now appears to be occurring in a number of rapidly declining populations. Conservation responses must urgently address causes of wetland loss and degradation, as well as enhancing monitoring and research so as better to inform appropriate conservation policies. National and international strategies and conservation instruments have scope to help, but need to be much more strategic in their implementation so as to address root causes.

Conference Paper↗

Conservation status of the buff-breasted sandpiper: Historic and contemporary distribution and abundance in south America

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.

The Wilson Bulletin↗