Researcher Richard Warner says grassland bird populations have declined as farmers turned more land from pasture to crop production.
The study was to determine whether birds might come back, even if the habitat was small.
The study found that birds did return and that their nesting success in the small grassy areas was high.
The researchers also noticed that birds would go into corn and soybean fields for insects to feed their young, something that might benefit farmers.
Warner says more research needs to be done to verify that.