James L. Pease, Faculty, Natural Resource Ecology and Management
Population trends for many grassland bird species have been in decline for years, concurrent with the intensification of agricultural production. Grazing systems provide a possible alternative to row-crop production that, properly applied, could yield economic returns for producers and still provide perennial cover for wildlife, especially birds.
To determine if a system of rotational grazing on warm- and cool-season grass pastures in southern Iowa can be devised that is valuable for both cattle and ground-nesting grassland birds.
We studied a system of rotational grazing on cool-season grass paddocks (May-June) and warm-season grass paddocks (July-August) on pastures in southwestern Iowa over a two nesting seasons and compared them to nesting in non-grazed cool-season and warm-season CRP fields. From earlier research on these and other southern Iowa fields, we knew that grassland birds use these paddocks for feeding, loafing, and other things but actual nesting use had not been documented. Using intensive nest-searching, nest monitoring, vegetation measurements, and careful pasture grazing pressure management, we have documented bird and cattle production on these paddocks. Results show considerable between-year variation in bird species abundance and use. The CRP warm-season control fields contained the highest rates of nesting success and bird diversity and cool-season CRP control fields had the fewest nests and bird species diversity. The grazed paddocks had mixed success between years but both had more nests than the cool-season CRP control. Based on our studies, we have made recommendations to area land-owners on how to manage grazing, in recommended plantings for warm-season paddocks, and in vegetation management. Such a system of warm-season refugia for birds during the critical nesting season, while requiring more management, does show compatibility between ground-nesting birds and cattle grazing.
Results have been shared at field days in conjunction with the Southern Iowa Livestock Forage and Livestock Committee and at two statewide grazing conferences and will be shared with wildlife professionals at the Midwest Fish and Wildlife Conference in December, 2007. In total, some 200 people have received the results thus far.
160 Natural Resources and Stewardship
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April 11, 2007
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