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La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

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Titre :	Estimating the abundance of Long-billed Curlews in Nebraska
Auteurs :	Cory J. Gregory, Auteur ; Stephen J. Dinsmore, Auteur ; Larkin A. Powell, Auteur ; Joel G. Jorgensen, Auteur
Type de document :	Article
Dans :	Journal of Field Ornithology (83(2) JUN 2012)
Article en page(s) :	122-129
Langues:	Anglais
Résumé :	Long-billed Curlews (Numenius americanus) are shorebirds of high conservation concern in North America. Populations have declined in the last 150 yr primarily due to habitat loss and conversion. We conducted a 2-yr study to estimate the density and statewide abundance of breeding Long-billed Curlews in Nebraska during 2008 and 2009. Surveys were conducted during the prenesting period in April when Long-billed Curlews were likely to be detected. We used a simple random sample of roadside survey routes (N= 39), each consisting of 40 5-min point-counts at 800-m intervals. We modeled detection probability and found that wind speed negatively affected detectability, but found no evidence of either year effects or observer bias. We estimated there were 0.0038 Long-billed Curlews per hectare (0.38 Long-billed Curlews per km2) along survey routes and, by extrapolation, estimated there were 23,909 (SE = 1685; 95% CI: 20,81027,471) Long-billed Curlews in Nebraska. Our population estimate suggests that similar to 15 to 22% of the United States population of Long-billed Curlews is found in Nebraska. Curlews were not evenly distributed within our survey area, with the highest densities in the central Sandhills, an area dominated by grass-stabilized sand dunes and shallow wetlands, and the lowest densities in predominantly agricultural areas. Because Long-billed Curlews in Nebraska face many potential threats resulting from land-use changes, monitoring of the breeding population should be continued. Our survey method was efficient and yielded interpretable results; other states or regions should consider adopting this approach for estimating curlew abundance.

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