Here Gordon Orians presents the results of his many years of research on how blackbirds utilize their marsh environments during the breeding season. These results stem from information he gathered on three species during ten breeding seasons in the Pacific Northwest, on Red-winged blackbirds during two breeding seasons in Costa Rica, and on three species during one breeding season in Argentina. Professor Orians concludes with an overview of the structure of bird communities in marshes of the world and the relation of these patterns to overall source availability in these simple but productive habitats.
