In 1974 I collected data on the growth relationships of Brown-headed Cowbirds and Dickcissels (Spiza americana) in prairie habitat in eastern Kansas (Konza Prairie Research Natural Area). The intensity of cowbird parisitism in this study was extremely high -- I found nests containing as many as nine cowbird eggs and three host eggs. More than one cowbird was evidently laying in many of the nests, behavior that may present some intricate evolutionary problems with respect to clutch-size manipulation of the cowbirds