The effects of agricultural change on population size of Corn BuntingsMiliaria calandraon individual farms

Abstract

This paper uses Common Birds Census (CBC) data to examine habitat selection by Corn Buntings and the relationship between population change and land-use change at the scale of the individual farm. On each of 29 farms, structural data and cropping patterns in the year of peak Corn Bunting population size were compared with those in the year of lowest population size (or first year of extinction). Crop diversity, hedgerow length, field size and the areas of all crops except wheat and barley did not differ significantly between years of highest and lowest Corn Bunting population. Barley was more extensive in years of highest Corn Bunting population and wheat more extensive in years of lowest population. Variation in Corn Bunting population density in a sample of 18 farms censused in 1974 could not be explained by variations in habitat diversity, hedgerow length, field size, altitude or the area of different erop types. This variation was also unrelated to either of the first 2 components of an ordination of ...