BIRDS OF THE ST. CROIX RIVER VALLEY 



17 



warbler, yellow warbler, northern waterthrush* (local), common yellow- 

 throat, red-winged blackbird, swamp sparrow*, and song sparrow. 



Agricultural Communities 



Cropland 



One of the most prominent aspects of the landscape in the lower Valley is 

 the presence of agricultural fields. According to figures from the U.S. 

 Department of Agriculture, there were at least 158,540 ha in the Valley 

 devoted to row crop or cereal crop production (row crop = 62.6%, cereal crop 

 = 37.4%) in 1967. By 1977, the totals had increased to 195,587 total ha 

 (73.2% in row crops, 26.8% in cereal crops). Of the nearly 1.8 miUion ha of the 

 Valley included in this report, 8.8% was devoted to row and cereal crop pro- 

 duction in 1967 and 11% in 1977. 



During the initial stages of agricultural development, important habitats 

 including native tall grass prairie, deciduous forest, and prairie wetlands 

 were destroyed to accommodate expanded production. Changes in land use 

 of the magnitude attributed to Cropland have had a serious impact on bird 

 populations and bird species diversity. Current agricultural practices of 

 fencerow to fencerow farming, clean farming, fencerow removal, and wind- 

 break removal to faciHtate center -pivot irrigation systems, produce addi- 

 tional stresses on bird populations. 



Corn, soybeans, oats, barley, and to a Umited extent, wheat, are the promi- 

 nent crops produced in this region. Although a common practice in western 

 Minnesota, summer fallowing the soil has only recently become popular in 

 this region. Characteristic breeding bird species that use Cropland include 

 gray partridge*, killdeer*, horned lark*, western meadowlark, red-winged 

 blackbird, and vesper sparrow. 



Hayland 



Domestic hay was produced on 128,927 ha in 1967 and 139,393 ha ( + 7.5%) 

 in 1977. Hayland accounted for 7.2 and 7.8% of the total area of the Valley in 

 1967 and 1977, respectively. This temporary habitat is important to a 

 variety of early nesting species. Hayland is also important in soil conserva- 

 tion because the soil is not laid bare each year and is not exposed to the 

 ravages of wind and water erosion as it is with row crops. Principal plant 

 species used in hay production include alfalfa, timothy, brome grass, and red 

 clover. 



Characteristic breeding birds associated with Haylands include American 

 bittern, mallard, blue-winged teal, pintail, marsh hawk, short-billed marsh 

 wren, bobolink*, eastern meadowlark*, western meadowlark, red-winged 

 blackbird, dickcissel*, savannah sparrow*, grasshopper sparrow*, Hen- 

 slow 's sparrow*, LeConte's sparrow, and song sparrow. 



Old Field Community 



The Old Field community represents a relatively small proportion of the 

 land area in the Valley. This habitat type develops when land is taken out of 

 agricultural production and allowed to develop by natural succession. Inva- 



