The effect of fine-scale variations in agricultural land use on the abundance of red-winged blackbirds.

Used censuses of breeding Agelaius phoeniceus and of land use to test the prediction that blackbirds should be most abundant where there is a mix of hayfield (breeding habitat) and corn production (feeding habitat) but fewer birds where either habitat predominates. Red-winged blackbird abundance increased in response to increases in both hayfields and cropland. Multivariate analysis including hayfield, cropland, and wetland abundance as explanatory variables explained substantially more variation in blackbird abundance than any of the variables could by themselves. -from Authors