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Résumé :
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Mountain Plover (Charadrius montanus) populations are inefficiently sampled by Breeding Bird Surveys. As a result, targeted sampling of select populations of this species (with an estimated global population of 11,000-14,000 birds) can be valuable. Our objectives were to determine the breeding distribution and estimate the size of the Mountain Plover population in Oklahoma. We conducted a randomized point count survey in an area where Mountain Plovers were previously known to breed and conducted additional surveys over a larger area to better delimit the distribution. We used a removal model to estimate detection probability for raw counts obtained from 1104 point counts in 2004 and 2005, and derived a state-level population estimate using the detection-adjusted counts. Mountain Plovers used flat, bare, cultivated fields for nesting, and their distribution was closely tied to the presence of clay loam soils. We estimated that at least 68-91 Mountain Plovers bred in Oklahoma in 2004-2005. The low breeding density we observed may be due to the location of our study area near the southeastern edge of the breeding range of these plovers, the low-quality habitat provided by cultivated landscapes, or a combination of factors. Because the number of birds is small, the status of the Oklahoma population is not likely to have a large effect on the global population. However, additional information is needed to help determine if cultivated landscapes represented population sources or sinks.
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