The predatory effect of nine species of forest birds on the large-larval and pupal stages of the black-headed budworm was investigated for 3 years. Successive bird collections and subsequent gizzard analyses within a season permitted the development of response curves that show changes in consumption in relation to changes in prey size, density, and other characteristics within the season. Percentage predation varied from 3 to 14% over the 3 years and strongly suggested that birds act in a density-dependent manner.