2015b), we found that tall, dense vegetation with a high percentage of forb cover is important for the sedge wren.
Loess plots of sedge wren (SEWR) density at (i(> sites within the Prairie Parkland Province ecoregion of Minnesota in 2013 and 2014, in relation to (A) lilter depth, (B) vegetation height, (C) percent grass cover within 4 in, (D) percent forb cover within 4 m, (E) percent shrub cover within 4 m, (F) percent standing dead vegetation cover within 4 m, (G) percent bare ground cover within 4 m, (H) visual obstruction reading (VOR).
During the 2 y of our study we recorded a total of 2967 grassland birds: 293 sedge wrens, 212 Savannah sparrows, 610 grasshopper sparrows, 111 Henslow's sparrows, 255 dickcissels, 1190 bobolinks, 129 western meadowlarks, and 167 individuals of other grassland bird species.
These site differences were consistent among species, though not significantly so in the case of sedge wrens (or for dickcissel, for percent tree cover).
Our results indicate that vegetation height was the most consistent variable for modeling three of the four species analyzed, with the probability of occurrence of Le Conte's Sparrow and Sedge Wren increasing with greater vertical structure, whereas Smith's Longspurs were more likely to occur in short structure.
Unlike Le Conte's Sparrow and Sedge Wren, this species typically occurs in flocks in winter, presumably to reduce predation risk in pastures with lower structure (Grzybowski, 1983).
Model-averaged parameter estimates, standard errors, 85% confidence intervals for parameters, scaling unit, and scaled odds ratio for competitive models predicting occurrence of Le Conte's Sparrow (Ammodramus leconteii), Sedge Wren (Cistothorus platensis), Savannah Sparrow (Passerculus sandwichensis), and Smith's Longspur (Catcarius pictus) at the Tallgrass Prairie Preserve, Oklahoma, 2008-2010.
We detected Sedge Wrens in 10 of 78 (13%) 1 ha plots surveyed in 2009 and five of eight patches.
For sedge wrens, the best detection model incorporated two cosine adjustments.
For both the mesic fields included in this study and the hydric fields, strip-shaped plots distributed the affected area throughout a field and may have diffused rather than concentrated any potential effects, although disking in strips likely better preserves habitat for dense-habitat specialists like common yellowthroats and sedge wrens (Benson, 2003).
The decreased vegetation density created by disking, if done at a larger scale, would possibly also benefit other species that prefer relatively sparse herbaceous vegetation such as grasshopper sparrows, although species dependent on dense herbaceous vegetation such as common yellowthroats and sedge wrens would likely decline (Fletcher and Koford, 2002; Benson, 2003; Murray and Best, 2003).
Species associated primarily with remnant prairie and CRP habitats were bobolink, eastern meadowlark and dickcissel, whereas sedge wren and Henslow's sparrow were found primarily in CRP (Fig.
Henslow's sparrow and sedge wren were indicator species for CRP habitat in both years (Table 1).