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The Center for Native Grasslands Management




Title: Effects of grazing Conservation Reserve Program lands in North Dakota on birds, insects, and vegetation
Year: 2001
Author(s): Kennedy, C. L., Jenks, J. A., Higgins, K. F.
Source Title: South Dakota Academy of Science
Source Type: Journal
pages: 213-226
Original Publication: http://  
Abstract: This study evaluated the effects of various land use practices on nongame birds, insect biomass, and vegetation structure on nongame birds, insect biomass, and vegetation structure in Conservation Reserve Program (CRP) grasslands in North Dakota. Breeding bird surveys were conducted and insect collections and vegetation measurements were taken in 3 of the 4 CRP tracks that were selected for the North Dakota CRP Demonstration Project, located in Bowman, Ward, and Stutsman Counties, North Dakota. Demonstration project treatments include a 3 pasture twice-over deferred rotation and season-long grazing system and haying. Twelve species of nongame passerine birds in 1992 and 10 species in 1993 used the demonstration project CRP fields. The lark bunting, grasshopper sparrow, red-winged blackbird, and brown-headed cowbird composed a majority of the species composition in 1992 and 1993. Mean density of male birds (all species combined) exhibited a downward trend from 1992 to 1993 which was most likely due to colder temperatures and greater precipitation in 1993. Among treatments, CRP tracts subjected to rotation or season-long grazing systems maintained equal or higher bird densities than idle fields (controls). Terrestrial insect biomass and, for the most part, vegetation height and effective leaf height, was lower in 1993 than in 1992. As expected, bird density, insect biomass, and vegetation structure values varied considerably among grazing treatments and controls, and by counties and years. Although some grazed treatments supported comparatively high bird densities, these pastures tended to have lower insect biomass and higher visual obstruction readings. Results suggest that high insect biomass in pastures with dense cover does not necessarily equate to high nongame bird use. Perhaps, open or less densely vegetated areas within CRP pastures are important components of cover-forage complexes that birds use. Results of this study also indicate that at certain stocking rates, grazing of CRP lands in North Dakota may be an acceptable practice; that is, a land use that provides benefits to the landowner and to nongame birds. Since grazed or hayed CRP is more valuable to wildlife than the annually tilled cropland it replaced, some grazing practices should be considered as an alternative to offer in negotiations in any extensions or modifications of CRP contracts in the future.
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