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Northern Prairie Wildlife Research Center

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Area Requirements of Grassland Birds: A Regional Perspective


Table 1.  Number of Conservation Reserve Program fields in the northern Great Plains in which point counts were conducted; number of point counts; and minimum, median, and maximum size of grassland patch containing fields.
County Number of fields Number of
Point Counts
Size of grassland patch (ha)
Minimum Median Maximum
Great Plains Roughlands
Butte, SD
27 72 54.6 142.7 269.7
Fallon, MT
29 59 27.8 112.2 231.4
Hettinger, ND
29 74 8.4 76.0 270.5
Missouri Coteau
Kidder, ND
40 93 14.6 123.8 224.0
McPherson, SD
37 105 16.2 118.2 206.9
Sheridan, MT
29 81 2.2 99.6 197.1
Drift Prairie
Day, SD
44 77 9.0 64.6 134.5
Eddy, ND
37 81 4.2 74.3 200.8
Black Prairie
Grant, MN
31 57 7.1 48.3 168.6
Total 303 699  


Table 2.  Effects of patch size on grassland birds in CRP fields in nine counties in the northern Great Plains.
Species Butte Day Eddy Fallon Grant Hettinger Kidder McPherson Sheridan
Northern Harrier
Mourning Dove
Eastern Kingbird
Sedge Wren
Common Yellowthroat
    +D -P    
Clay-colored Sparrow
    +PFD   +D   +D
Grasshopper Sparrow
      +PFD   +PD   -PFD  
Baird's Sparrow
+PFD   +D          
Le Conte's Sparrow
Lark Bunting
Savannah Sparrow
-P             +D
  +PF +P +PFD +D  
Western Meadowlark
      +D -P      
Red-winged Blackbird
+D     +D     -P -PF  
Brown-headed Cowbird
Results are denoted "P" for logistic regression on presence or absence data, "F" for linear regression on frequency of occurrence, and "D" for linear regression on density. Upper-case letters indicate that patch size was included in model selected by Akaike's Information Criterion. Plus sign (+) indicates that patch size had positive effects on response variable; minus sign (-) indicates negative effects. No entry indicates that patch size was not included in the model. A dash (—) indicates that the species was not common enough in that county to analyze.