C. Boutin et al., Farmland birds in southern Ontario: field use, activity patterns and vulnerability to pesticide use, AGR ECO ENV, 72(3), 1999, pp. 239-254
The use of cropfields by birds is largely unknown in southern Canada and co
nsequently the risk incurred by pesticide use on bird populations cannot be
adequately characterised. The activity patterns and relative interior to e
dge use of bird species were examined for four crops in southern Ontario to
assess the susceptibility of different species to pesticide use. Altogethe
r 138 species were identified in the four crops over the 2 year period but
only 25 species were recorded during 50% of visits in at least 1 month: 14
in corn (Zea mays L.), 16 in soybean (Glycine max L. Merr,), 14 in apple (M
alus spp.) orchards and eight in vineyards (Vitis spp.). Territorial behavi
our was an important activity for several species from May through July in
the four crops. Nesting was confirmed in May June and July for most species
, with the exception of American Goldfinch Carduelis tristis, Chipping Spar
row Spizella passerina and Cedar Waxwing Bombycilla cedrorum which nested i
n August/September. Foraging was the most important activity for most speci
es in all months (7/10 species in May, 6/8 species in June, 4/8 species in
July, 5/8 August/September). Few fledgling young were observed. Most specie
s used field edges consistently more often than expected in corn and soybea
n fields, according to the edge/interior ratio, Yellow Warbler Dendroica pe
techia being the exception. In apple orchards, relatively few species diffe
rentiated between edge and interior. Based on their frequency of occurrence
(>50%), behaviour and temporal coincidence with pesticide applications, 13
species were considered most at risk: Killdeer Charadrius vociferus, Horne
d Lark Eremophila alpestris, American Crow Corvus brachyrhynchos, American
Robin Turdus migrator-ius, European Starting Sturnus vulgaris, Chipping Spa
rrow, Vesper Sparrow Pooecetes gramineus, Savannah Sparrow Passerculus sand
wichensis, Song Sparrow Melospiza melodia, Red-winged Blackbird Agelaius ph
oeniceus, Common Crackle Quiscalus quiscala, Brown-headed Cowbird Molothrus
ater and Barn Swallow Hirundo rustica. The latter species, because of its
foraging habit, is less likely to be exposed to pesticides. This study was
important to identify focal species that can be used for detailed investiga
tions on exposure to pesticides. (C) 1999 Elsevier Science B.V. All rights
reserved.