Bird use of terraces in rowcrop fields was evaluated during 1996–1997 in southwestern Iowa by line transect counts of birds, nest searches and nest monitoring. Twenty-six bird species were observed in terraces. Red-winged blackbirds (Agelaius phoeniceus) and dickcissels (Spiza americana) were most abundant, accounting for 58% of the total bird abundance. Bird abundance in terraces (x̄ = 463.0 birds/100 ha, se = 33.0) was less than that in other strip-cover habitats such as grassed waterways and roadsides, but greater than that in rowcrops. Five species nested in terraces. We found 64.8 nests/10 ha of which 76% were red-winged blackbird nests. Predation resulted in failure of 73% of all nests. The relative contribution of terraces to grassland bird conservation is minor, and changes in current terrace management practices would not likely improve conditions for birds nor be economical.
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The American Midland Naturalist
Vol. 145 • No. 2
April 2001
Vol. 145 • No. 2
April 2001