Fritz L. Knopf James A. Sedgwick 1987 We studied avian habitat relationships and the impact of grazing on breeding densities of selected migratory birds in a plains cottonwood (<i>Populus sargentii</i>) bottomland in northeastern Colorado. Five 16-ha plots served as controls and 5 were fenced and fall-grazed October-November 1982-84 following a season of pre-treatment study in the spring of 1982. We focused our analysis on bird species directly dependent on the grass-herb-shrub layer of vegetation for foraging, nesting, or both. The guild included house wren (<i>Troglodytes aedon</i>), brown thrasher (<i>Toxostoma rufum</i>), American robin (<i>Turdus migratorius</i>), common yellowthroat (<i>Geothlypis trichas</i>), yellow-breasted chat (<i>Icteria virens</i>), and rufous-sided towhee (<i>Pipilo erythropthalmus</i>). Moderate, late-fall grazing had no detectable impact on calculated densities of any of the 6 species, implying that proper seasonal grazing of a cottonwood floodplain is, at least initially (3 years), compatible with migratory bird use of a site for breeding. Habitat associations suggested that common yellowthroats and yellow-breasted chats were most unique and most likely to respond negatively to higher levels of grazing. We suggest that these latter 2 species are appropriate ecological indicators of the quality of ground-shrub vegetation as breeding bird habitats in lowland floodplains of the Great Plains. application/pdf 10.2307/3801661 en Wildlife Society Breeding bird response to cattle grazing of a cottonwood bottomland article