Aerial invertebrate abundance and foraging barn swallows over pasture fields

Aerial invertebrate abundance over pasture fields in lowland mixed farmland in southern Britain was more than double that over silage, and more than three and a half times greater than that over cereal fields. Pasture fields also hosted approximately twice as many foraging barn swallows as both silage and cereal fields. Past reductions in the availability of pasture may have reduced the numbers of aerial invertebrates, and may have contributed to barn swallow Hirundo rustica population declines, and possibly those of other aerial insectivores.

Authors: K. L. Evans, J. D. Wilson and R. B. Bradbury (2007) Agriculture, Ecosystems & Environment 122, 267-273
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T3Y-4N5CSFX-…