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, informati on is needed on bird use of farmland in much of Canada, including the Mixed wood Plains ecozone of southern Ontario. We examined the pattern of bird us e of four crop types in three counties of southern Ontario (6 corn and 6 so ybean 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 coun ties (1987-1988 combined), 25 were seen on 50% of visits and 16 at frequenc ies 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 Niag ara, whereas in Essex, soybeans had more species than corn. The species mos t frequently observed in cornfields were Song Sparrow (Melospiza melodia), European Starling (Sturnus vulgaris), Red-winged Blackbird (Agelaius phoeni cens) and Common Grackle (Quiscalus quiscula). In soybean fields, the most frequently recorded species were Horned Lark (Eremophila alpestris), Song S parrow 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) a nd American Goldfinch (Carduelis tristis) were the species most commonly ob served. Most species occurred uncommonly (recorded on < 25% of visits) in a ll months, and very few species were recurrent (75% of visits). Omnivorous and insectivorous species were most abundant in all crop types, and more gr ound feeders were observed than species foraging in the canopy, aerially or in aquatic habitats. Thirty-five species were only recorded during the mig ration period of August/September.