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COPYRIGHT 2005 Wilson Ornithological Society
The Mountain Plover (Charadrius montanus) breeds primarily in the shortgrass prairies of Colorado, Wyoming, and Montana (Graul and Webster 1976) but breeds as far north as Canada and as far south as Mexico (e.g., Graul and Webster 1976, Day 1994, Knopf 1996, Shackford et al. 1999, Manning and White 2001). Colorado is considered the continental stronghold for Mountain Plovers, with over 60% of the population believed to breed there (Kuenning and Kingery 1998). The habitat types used by breeding Mountain Plovers within shortgrass prairie may contain areas grazed by native herbivores, such as bison (Bison bison) and black-tailed prairie dogs (Cynomys ludovicianus), or domestic herbivores, including cattle and sheep. Mountain Plovers also nest in agricultural fields (Knopf 1996, Knopf and Rupert 1999, Shackford et al. 1999). Landscape-level habitat use by breeding Mountain Plovers may be influenced by the distribution of these habitat types.
Landscape-level characteristics, such as the size, distribution, shape, and availability of different habitat types, are important to a species' population dynamics and regulation (Kareiva 1990, McKelvey et al. 1992, Schmiegelow and Monkkonen 2002, Crozer and Niemi 2003). The distribution of individuals among habitats reflects an ability to discriminate between habitat types and assess habitat quality (Poysa et al. 2000), and differences in habitat affinity may partially explain the wide range of avian responses to loss of native habitat (Sekercioglu et al. 2002). Landscape configuration and proximity of resources provided by different habitat types may be critical to the breeding success of Mountain Plovers. Suitable breeding habitats minimize the energetic costs of foraging and reduce exposure to predators (Poysa et al. 2000). Here, we report the relationship between movements and home-range sizes of Mountain Plovers during the brood-rearing period within three different habitat types.
METHODS
Information on brood-rearing activity of Mountain Plovers was collected in eastern Colorado from 2001 to 2003 during other ongoing studies in three different habitat types: rangeland, black-tailed prairie dog towns, and agricultural fields. In high-elevation (2,600-3,500 m) rangeland in Park County, Colorado, the habitat consisted primarily of slimstem muhly (Muhlenbergia filiculmis), and, to a lesser extent, blue grama (Bouteloua gracilis) grazed by domestic bison or cattle (Wunder et al. 2003). Our prairie dog study areas, located in Lincoln and Weld counties in eastern Colorado (also characterized as rangeland) were dominated by blue grama and buffalograss (Buchloe dactyloides). Only 1.94% of eastern Colorado is occupied by prairie dogs (White et al. 2005), and, in our study area, we knew of only one prairie dog complex (>10,000 ha)--a network of small (mean = 80 ha; range = 1-340 ha), active prairie dog towns within 800 m of each...
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