In areas of conventional oil and gas development, the amount of cleared area, length of roads and amount of edge all increased with increasing well density and amount of core forest declined. At high well densities, 85 percent of the study site remained forested, but the mean amount of core forest declined from 68 to 2 percent. Forest Service scientists found that ovenbird, Blackburnian warbler, and black-throated green warbler had lower abundance at well sites than at reference sites. Six species, including American robin, chestnut-sided warbler, and brown-headed cowbird, were more abundant at well sites than reference sites. Avian communities differed between northern hardwood and oak forest types at reference sites but became more similar when wells were present at both scales. The bird communities associated with northern hardwoods and oaks still retained their unique characteristics at low well densities but became similar at high well densities, suggesting a threshold somewhere between the low and high well density sites. Consequently, if well development is to occur in extensively forested landscapes, conventional oil and gas well development should be limited to a maximum of 20 wells per square kilometer to minimize impacts to forest birds.