The RSPB has issued revised guidelines on survey to establish the presence of cirl bunting on a site (March 2014; available here).
The cirl bunting Emberiza cirlus is a Wildlife and Countryside Act Schedule 1 species. Once widespread and locally common across much of southern England, cirl buntings are now rare and very range restricted and, until recently, only bred in south Devon where they are mostly confined to coastal and inland areas between Plymouth and Exeter. The population is now beginning to expand east of the Exe Estuary.
Cirl buntings are birds of mixed farmland and the loss of sources of food (both winter and summer) and nesting sites was identified as the major reason for the cirl bunting’s dramatic decline. During the winter, cirl buntings forage in weedy stubble fields, feeding on seeds and spilt grain. In the summer, they nest in hedges or scrub and forage in unimproved grassland full of invertebrates; grasshoppers are a particularly valuable food for chicks. As cirl buntings are very sedentary only moving up to 2 km between their breeding and wintering areas, it is vital that all these habitats are within close proximity to each other.