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.