Bird populations have long been considered to provide a good indication of the broad state of wildlife in the UK. This is because they occupy a wide range of habitats and respond to environmental pressures that also operate on other groups of wildlife. In addition there are considerable long-term data on changes in bird populations, which help in the interpretation of shorter term fluctuations in numbers.
The bird population indices have been compiled in conjunction with the Royal Society for the Protection of Birds (RSPB), the British Trust for Ornithology (BTO) and the Joint Nature Conservation Committee (JNCC).
For more statistics about the status of bird populations internationally, please see the Pan-European Common Bird Monitoring Scheme website.