BREEDING BIRD ABUNDANCE AND HABITAT ON TWO LIVESTOCK GRAZING REGIMES IN NORTH DAKOTA

To help sustain prairie wildlife habitat on privately owned lands in North Dakota, prescribed rotational grazing (RG) systems have been implemented as part of the Prairie Pothole Joint Venture (PPJV) of the North American Waterfowl Management Plan. However, impacts of these systems on nongame breeding birds are unmeasured. During 1996 and 1997 we assessed the relative abundance, species richness, and habitat of breeding birds especially passerines on five PPJV-prescribed RG pastures in central and northwestern North Dakota. Each RG pasture was paired with a nearby traditional, continuous-grazed (CG) pasture for comparison. Using 5-minute point counts on 100-m radius plots to survey breeding birds, we recorded 30 species in 1996 and 29 species in 1997. We detected no differences in relative abundance or species richness between grazing regimes in 1996 (P = 0.29 and 0.58), but relative abundance and species richness were greater on RG pastures than on CG pastures in 1997 (P = 0.08 and 0.04), a relatively dry year. A group of five species (savannah sparrow [Passerculus sandwichensis], grasshopper sparrow [Ammodramus savannarum], western meadowlark [Sturnella neglecta], bobolink [Dolichonyx oryzivorus], Baird’s sparrow [Ammodramus bairdii]) considered sensitive to heavy grazing in previous studies had a higher collec