Changes in land use, agricultural practices, and the subsequent reduction of mosaic grasslands, which vary spatially and temporally in structure, have resulted in dramatic and range wide population declines of grassland birds. These grassland species have exhibited more substantial and continuous population declines than any other behavioral or ecological guild. To understand the impact of agricultural practices, we investigated if grassland bird communities differed on dairy pastures and grassland fragments and if vegetation structure and composition contributed to bird community differences in southwest Michigan, United States. Rather than relying on bird counts, we created utilization distributions to analyze these bird communities. Correspondence analysis indicated that pasture and grassland bird communities differed. Based on this analysis, specific species showed a stronger association with dairy pastures or grassland fragments. Canonical correlation analysis confirmed that vegetation structure and composition contributed to variation in species distributions, suggesting that species-specific associations found in the correspondence analysis were, at least partially, due to the vegetation structure of the dairy pastures and grassland fragment. Species-specific models indicated that some grassland birds were associated with unique vegetation characteristic. We concluded that species-specific habitat requirements are generally fulfilled through mosaic grasslands and that both grasslands and agriculture fields should be managed to maintain mosaic vegetation structure, that varies spatially and temporally in order to maintain a diverse community of grassland bird species.
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