Constant effort: Studying avian population processes using standardised ringing

Bird ringing has played a central role in the study of avian populations, both through providing data and in stimulating the development of analytical methods. Constant‐effort (CE) ringing provides an effective way of monitoring bird populations through standardising ringing effort. In Britain & Ireland CE ringing began in the early 1980s, and CE schemes now operate in nearly twenty countries across two continents where they provide annual information on abundance, productivity and survival for a range of common passerine birds. CE schemes fulfill three aims: to monitor demographic rates in bird populations; to establish links between these demographic rates and population changes and environmental conditions; and to inform habitat management to conserve populations. We give examples of how CE ringing has been used to address these objectives and briefly discuss possibilities for future developments that will further enhance the value of CE data.