Without knowledge of the distribution and size of populations and how they are changing, the actions of conservationists must necessarily be based upon hunches and intuition that have a high chance of failing the species or habitats they wish to conserve. Fortunately, for bird conservationists in the UK, there is a long tradition of volunteer support for ornithological surveys and monitoring, and the British Trust for Ornithology has been the medium for channelling much of these efforts towards well-structured programmes of increasing value. The statutory conservation bodies in the UK were farsighted enough to realise the superb cost-effectiveness of volunteer monitoring by contracting the BTO to provide monitoring data from the early 1960s. This overview covers changes in population size as well as changes in reproductive success and survival that might have caused the population changes. When a declining population is detected, the BTO can inform conservationists of which stage of the life-cycle appears to have been detrimentally affected.
Conservationists are thereby able to target their action or further research effectively.
This is the main function of the BTO's Integrated Population Monitoring programme for UK birds. To identify the stage of the life cycle at which changes are taking place. To provide data that will assist in identifying the causes of change. To distinguish changes in populations induced by human activities from those that are natural population fluctuations. The programme brings together data from several long-running BTO schemes.