Spatial and temporal patterns of bird use of farmland in southern Ontario

To assess the factors behind possible global declines in some birds and to investigate the vulnerability of birds to agricultural practices, information is needed on bird use of farmland in much of Canada, including the Mixedwood Plains ecozone of southern Ontario. We examined the pattern of bird use of four crop types in three counties of southern Ontario (6 corn and 6 soybean fields, Essex County; 5-6 cornfields and 5-6 apple orchards, Norfolk County; 6 cornfields and 6 vineyards, Niagara County) during July-September 1987 and May-September 1988. Of the 138 species recorded in all three counties (1987-1988 combined), 25 were seen on 50% of visits and 16 at frequencies between 25 and 50% of visits in at least one crop during any one month. Cornfields had more species than orchards in Norfolk and vineyards in Niagara, whereas in Essex, soybeans had more species than corn. The species most frequently observed in cornfields were Song Sparrow (Melospiza melodia), European Starling (Sturnus vulgaris), Red-winged Blackbird (Agelaius phoenicens) and Common Grackle (Quiscalus quiscula). In soybean fields, the most frequently recorded species were Horned Lark (Eremophila alpestris), Song Sparrow and Common Grackle, whereas in orchards, Chipping Sparrow (Spizella passerina) was the most frequently recorded species. In vineyards, American Robin (Turdus migratorius), Savannah Sparrow (Passerculus sandwichensis) and American Goldfinch (Carduelis tristis) were the species most commonly observed. Most species occurred uncommonly (recorded on < 25% of visits) in all months, and very few species were recurrent (75% of visits). Omnivorous and insectivorous species were most abundant in all crop types, and more ground feeders were observed than species foraging in the canopy, aerially or in aquatic habitats. Thirty-five species were only recorded during the migration period of August/September.