Avian use and vegetation characteristics of conservation reserve program fields

We compared avian use of Conservation Reserve Program (CRP:I fields enrolled in the CP1 (cool-season grasses and legumes) and CP2 (warm-season native grasses) options in southeastern Nebraska from 1991 to 1995. In winter and in the breeding season CP2 fields had taller, denser vegetation than CP1 fields, However, total bird abundance did not differ between CP1 and CP2 fields (P = 0.47). Dickeissels (Spiza, americana) and grasshopper sparrows (Ammodramus savannarum) were the most abundant species during the breeding season although population numbers varied among years (P ( 0.001). Dickeissels and grasshopper sparrows showed no differences in abundance between CPs, but dickcissels were associated with tail, dense vegetation and grasshopper sparrows with sparser vegetation and a shallow litter layer. Bobolinks (Dolichonyx oryzivorus) were more abundant on CP1 fields (P = 0.001), and common yellowthroats (Geothlypis trichas) and sedge wrens (Cistothorus platensis) were more abundant oil CP2 fields (P = 0.001 and P = 0.05). Average winter abundances did not change over years (P = 0.90). American tree sparrows (Spizella arborea) and ring-necked pheasants (Phasianus colchicus) were the most abundant species during winter and were more abundant on CP2 fields (P < 0.05), Meadowlarks (Sturnella spp.) were more abundant on CP1 fields in winter (P < 0.05).