Riparian Width and Neotropical Avian Species Richness in the Agricultural Midwest

Abstract

Neotropical migratory birds have declined in recent decades in the agricultural Midwest and
a conservation need is to determine the minimum size of riparian buffer areas needed to support diverse
populations of Neotropical migrants during the breeding season. Thirty-six sites were surveyed along the west
side of a 17 km stretch of the Mississinewa River in east-central Indiana, each adjacent to an area with
agriculture as the primary land use. Sites were divided into three categories based on the width of the riparian
buffer (< 25 m, 25–75 m, and >75 m) and surveyed three times each during the breeding season. In total,
56 species of birds were identified, including 25 species of Neotropical migrants. A positive correlation was
noted between Neotropical species richness and riparian buffer width, however no difference in species
richness was noted between medium and wide sites suggesting that widening riparian buffers to 75 m in the
agricultural Midwest would be a practical conservation target and help protect all but the most area-sensitive
species such as Acadian Flycatcher (Empidonax virescens) and Wood Thrush (Hylocichla mustelina).
Vegetative characteristics had little impact