We evaluated the influence of landscape composition on bird use of rowcrop
(corn and soybean) fields in 6 watersheds in Iowa from mid-May to late July
1993 and 1994. We counted birds within 50-m-radius circular plots position
ed randomly within rowcrop fields and determined coverages for 21 habitats
within 800-m-radius circles centered on each bird census plot. We evaluated
the relationships between bird abundances in rowcrop fields and the habita
t coverages in the landscape by using 2 multivariate procedures. We derived
3 landscape scenarios from a cluster analysis of the original habitat vari
ables; the abundances of 7 bird species different significantly among the 3
scenarios. Species abundances in rowcrop fields were greater in landscapes
with more grassland block-cover and/or more wooded block-cover and strip-c
over. Principal component analysis illustrated the responses of bird specie
s to landscape composition: species responses depended upon the relative us
e (ranging from resident to occasional) that the birds made of the lowcrop
fields. Habitat selection and use in birds is a multiscale phenomenon, and
the landscape context should be considered when evaluating bird use of rowc
rops.