Final Report: Surveys and Investigations Projects as Required by Federal Aid inWildlife Restoration Act, Missouri. (Includes Study No. 1, Job No. 1, and Job No. 2)

摘要

During 1993-1995, we monitored vegetative conditions and avain abundance,composition, and productivity on 8 blocked sites in northern Missouri containing CP1 (cool-season grass), CP2 (warm-season grass), and rowcrop fields. Total bird abundance (P less than 0.0001 in 1994), grassland bird abundance (P less 0.05 in 1994 and 1995), nest density (P less than 0.001 each year), and number of nesting species (P less than 0.05 each year) were all lower on crop fields than on CRP fields. The bird community using crop fields markedly differed from that of CRP fields, with short-grass and open-ground feeding birds predominant on crop fields. Grassland bird species richness (P equals 0.057 in 1993, P less than 0.0001 each year), Henslow's sparrows (Ammodramus henslowii) (P less than 0.001 in 1993 and 1995), meadowlarks (Sturnella spp.) P less than .01 in 1993 and 1995, and American goldfinches (Carduelis tristis) (P less than 0.01 in 1994 and 1995) were higher on the structurally diverse than on CP2 fields. CP2 fields were tall, dense warm-season grass monocultures having higher abundances of red-winged blackbirds (Agelaius phoeniceus) (P less than 0.05 in 1994) and common yellowthroats (Geothylpis trichas) P less than 0.001 each year than CP1 fields. Difference in nesting success and nest densities of species between CP1 and CP2 fields, although rarely significant, were similar to those of relative abundance. The conservation value of CRP fields for declining grassland bird species was higher for CP1 fields than for CP2 fields; species of concern were either more abundant in both CP types. Monotypic stands of both warm-season and cool-season grasses should be avoided to increase the potential wildlife benefits of CRP and other idle grassland habitats.