Use of farmland riparian strips by declining and crop damaging birds

Abstract

Riparian strips prevent river bank erosion, help to maintain water quality, and contribute to the maintenance of biodiversity in agro-ecosystems. These areas are often perceived by farmers as potential breeding habitats of animals and plants that are harmful to crops. Consequently, the vegetation in riparian strips is periodically subjected to grazing, mowing, burning and/or herbicide spraying. Bird use was compared among six types of farmland riparian strips (grazed, grassy herbaceous, non-grassy herbaceous, low shrubby, tall shrubby, and wooded) in the agricultural landscape of southern Québec (Canada). These strip types constituted a gradient with respect to plant diversity, vegetal structure, and plant cover control or disturbance. The objectives of this study were to document the avian communities of these riparian strip habitats to determine (1) their respective contribution to bird conservation and (2) their role as potential breeding habitats for crop damaging bird species. Bird abundance and species richness were greater in the wooded and tall shrubby strips than in the other riparian strips. Abundance of crop damaging species was significantly greater in wooded strips than in any other type; however, Red-winged Blackbirds, the most abundant bird species recorded and the species most likely to damage crops in the study area, did not differ in abundance among the six strip types, nor in adjacent crop fields. Diversified riparian strip habitats that include trees and tall shrubs can contribute to the preservation of avian diversity in agricultural landscapes, without providing significant breeding habitats for birds harmful to agriculture.