Bird monitoring provides one of the most robust and globally recognised methods for measuring changes in the state of biodiversity and the broader environment. Currently the UK Farmland Bird Indicator is one of the UK Government’s 15 sustainable development indicators (the only biodiversity indicator) and the European farmland bird indicator, led by Birdlife International is part of the key EU indicator set. The prevalence of this indicator is partly due to the biology of birds as they are high in food chains and respond rapidly to change, but is also because birds are visible, inexpensive to survey and are therefore very popular with amateur naturalists. Analyses of pan-European farmland bird data have shown the impact of intensive farming practices on bird numbers and have been responsible for major policy changes. Monitoring of seabirds is increasingly showing the public exactly what is happening in marine environments.
In order to determine trends, birds must be monitored in systematic and easily repeated ways using the same criteria such as location, time of the year, recording methodology etc. each time. It is often easy for observers to get a feel for species and to see that the population has changed over time, for example everyone ‘knows’ that skylark Alauda arvensis is now not as common in Jersey as it once was. However, can we show that decline and see when it happened and at what speed?