Current US energy policy seeks alternatives to fossil fuels to meet domestic energy demands. Lignocellulosic ethanol produced from native grasses has been proposed as an alternative source for transportation fuel. This could lead to widespread establishment of switchgrass fields to meet this need. Such plantings have the potential to create habitat for many grassland bird species with declining populations. Will these newly established grasslands provide adequate habitat for grassland birds? To address this knowledge gap, we characterized the avian community within 11 fields of varying plant species composition. We used distance sampling to characterize the avian community. We characterized the territories of three common birds, Sedge Wren, Common Yellowthroat and Song Sparrow, in each field and used territory size as an index of habitat quality. The composition of the floristic community was determined in 30 plots in each field by identifying species and percent cover. These vegetation data were used to determine a field-level Floristic Quality Index (FQI). Regression analysis was used to determine relationships between the vegetation and the avian community characteristics. We hypothesize that a.) avian community richness be positively correlated with FQI and b.) territory size will decrease and density will increase as FQI increases.
Results/Conclusions Regression analysis suggests a relationship between the territory size of Song Sparrows and FQI, however no relationship was found between the size of Sedge Wren or Common Yellowthroat territory size and FQI. Bird species richness showed no relationship to FQI, nor did Common Yellowthroat density. These preliminary results indicate that differences in bird species richness and territory size are not entirely dependent upon the composition of the floristic community. Other analysis, examining the relationship between plant species diversity and territory size, bear similar patterns to that seen in the presented analysis. Differences in species richness and territory size of each species across fields are apparent, but what factors are driving this difference? Landscape composition may influence the presence of certain species of birds. Some mean territory sizes are driven by single extremely large or small territories, which may be due to within-field variation in habitat quality. Further analysis will consider within-field floristic variation and its effect on territory size. We will also explore the relationship between the composition of the arthropod community within each field and territory size and bird species diversity.
