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Bird Use and Nesting in Conventional,
Minimum-tillage, and Organic Cropland

Introduction


Although most of the Prairie Pothole Region of North Dakota is cultivated (Stewart and Kantrud 1972), bird use of cropland is poorly known. The value of croplands as habitat for prairie birds is usually considered low in comparison to grasslands due to the soil-disturbance and possible negative effects from the application of chemicals (Graber and Graber 1963, Higgins 1977, Hill and Fleming 1982, Castrale 1985, Brewer et al. 1988). However, new cropping practices that use less tillage and less chemicals are being implemented on an increasing number of ha in North America. In 1991, North Dakota had more than 260,000 ha in minimum-tillage (Conserv. Tec. In. Cent. 1992) or organic farming (F. L. Kirschenmann, Farm Verified Organic, Medina, N.D., pers. commun.) primarily to reduce soil loss and minimize pesticide use.

There is some evidence that alternative cropping systems provide more food and cover for wildlife than conventional tillage methods in the form of crop residue, waste grain, and increased insects (Castrale 1985). Birds that use cropland during the migration, breeding, and winter seasons should be benefitted by these added food and cover resources. We hypothesized that alternative cropping practices would probably affect grassland passerines, upland-nesting shorebirds, and waterfowl, 3 avian groups that have shown declines in recent years (Robbins et al. 1986).

The primary objectives of this study were: (1) to estimate and compare the number of species and density of birds using fallow, sunflower, and wheat in conventional, minimum-tillage, and organic fields during breeding, migration, and winter seasons, and (2) to estimate and compare the number of species and density of nesting birds in fallow, sunflower, and wheat in conventional, minimum-tillage, and organic fields.

The study was supported by the Northern Prairie Science Center, National Biological Service, and by a grant from the Low Input Sustainable Agriculture program. We appreciate the cooperation of the Northern Plains Sustainable Agriculture Society and the Manitoba-North Dakota Zero Tillage Farmer's Association. We thank R. O. Woodward for leading the field crew, and we thank the field assistants: N. L. Darnall, S. W. Gillihan, J. Gustafson, J. A. Hershner, D. J. Hugelen, P. J. Neal, S. A. Norland, S. G. Peterson, T. M. Stark, J. M. Steiner, and L. C. Wyckoff. We thank L. D. Igl, D. H. Johnson, and R. R. Koford for comments on the manuscript and we appreciate the statistical help from W. E. Newton and T. L. Shaffer.


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