Bird use of three types of field margins in relation to intensive agriculture in Québec, Canada

Habitat structure and bird use of field margins were studied in intensive farmlands of southern Québec, Canada. The main objectives were: (1) to assess the value of field margins for conserving avian diversity in agricultural landscapes, (2) to document their potential as breeding habitats for bird species particularly those considered as nuisance for crops, and (3) to describe habitat variables that best explained bird use of field margins. Three types of field margins were distinguished: (a) natural hedgerows ( n=27) with well developed tree and shrub strata, (b) planted windbreaks ( n=17) mostly composed of coniferous trees and generally devoid of a well structured shrub stratum, and (c) herbaceous field margins ( n=17) with isolated shrubs. A total of 42 bird species were recorded. Bird use of hedgerows and windbreaks was similar, herbaceous field margins having fewer bird species and individuals than the other two types of field margin. Field margins did not contribute significantly as breeding habitats of bird species that may damage crops, but offered shelter to a broad range of species potentially useful for biological pest control. Bird use of field margins was mostly related to hedges’ structural complexity and dimension. Conserving natural hedgerows, minimising mechanical and chemical control of the vegetation in field margins, and planting a mix of deciduous and coniferous species in windbreaks represent efficient conservation strategies both from a wildlife and an agronomic point of view.