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Effects of Grazing on Nongame Breeding brids, Insects, and Vegetation in Conservation Reserve Program Grasslands in North Dakota
Thesis - University Access Only
Master of Science (MS)
Department / School
Wildlife and Fisheries Science
Kenneth F. Higgins
This study evaluated the effects of various land use practices 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 rotational 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.
Library of Congress Subject Headings
Conservation Reserve Program (U.S.)
Grazing -- North Dakota
Grassland ecology -- North Dakota
Habitat conservation -- North Dakota
Includes bibliographical references (page 59-64)
Number of Pages
South Dakota State University
Copyright © 1994 Carmen L. Kennedy. All rights reserved.
Kennedy, Carmen L., "Effects of Grazing on Nongame Breeding brids, Insects, and Vegetation in Conservation Reserve Program Grasslands in North Dakota" (1994). Electronic Theses and Dissertations. 498.