Effects of shrub coverages on birds of North Dakota mixed-grass prairies
We studied the distribution and density of passerine birds in relation to Wolfberry (Symphoricarpos occidentalis) and Silverberry (Elaeagnus commutata) shrub coverages on mixed-grass prairies of central North Dakota. Birds were counted along shrubby and shrubless transects during the 1982 breeding season. Species richness and total density of birds were greater on shrubby transects. Five species were more abundant on shrubby transects. Availability of woody nesting substrates best explained differences in bird species abundances. Differences in shrub coverages between transects were probably the result of different land-use practices. Land management practices which modify shrub coverages can alter the composition of passerine bird communities.