Northern Prairie Wildlife Research Center
Because CRP habitat is new, evaluations of its value to wildlife are limited. Studies have been completed on nesting in CRP fields by ducks (Luttschwager 1991; Kantrud 1993) and by Ring-necked Pheasants (Berthelsen et al. 1990; see American Ornithologists' Union 1983 for scientific names). King (1991) surveyed birds on 4-6 CRP fields and some alternative habitats in eastern Nebraska during 1989-1990. Attempts have been made to measure habitat changes resulting from CRP and to predict subsequent effects on certain birds through various models (Hays et al. 1989; Stauffer et al. 1989). As yet, however, little published information exists on actual use of CRP fields by birds, especially nongame species. Elsewhere we (Johnson and Schwartz, in press) documented the significance of CRP fields to breeding grassland birds in the northern Great Plains. The present paper describes in greater detail some of the characteristics of the CRP fields we studied in 1990-1992. We also develop models assessing the influence of certain variables on the density of the most common species. Explanatory variables include geographical and temporal indicators, conservation practice employed, and vegetation structure.