Abstract
A classification system for coding the habitats of British and Irish birds has been designed for use in ‘extensive’ ecological studies, i.e. where data are contributed by many observers. The system is based mainly on the vegetation structure of habitats and requires no expert botanical knowledge. It has advantages over several existing habitat classifications because it embraces agricultural and manmade sites as well as semi-natural ones, and it also includes aspects of land-management and human activity. The system described in this paper has, however, been designed to be as fully compatible as possible with other widely-used classifications. It has been implemented within the BTO Nest Record Scheme and its use will be extended throughout the BTO's Integrated Population Monitoring Programme.