In order to carry out comprehensive trend analyses of the bag data for birds, we rely on external funding. The first detailed analysis was carried out in the early 1990s by Dr Stephen Tapper, with the financial support of the Joint Nature Conservation Committee (JNCC). The results were reported in Game Heritage: An Ecological Review from Shooting and Gamekeeping Records, published by Game Conservancy Ltd in 1992.
A second comprehensive analysis was carried out in 2007, thanks to funding from Defra and the Scottish Executive. This joint project with the British Association for Shooting and Conservation (BASC) evaluated the potential of using data collected under the GWCT’s National Gamebag Census and BASC’s Waterfowl Shooting Survey schemes to monitor the harvest of huntable birds and other bird species in the UK (report available for download from Defra).
Unfortunately, we have been unable to obtain the resources to put together pages containing the level of detail on individual bird species that we have been able to do for mammals through the Tracking Mammals Partnership. Hence individual bird pages are restricted to summarising national trends in bags for quarry species of special interest, and are updated as time and resources allow.
We base our analysis on sites that have returned bag records for at least two years. The trends in bags are based on all records received, whether or not releasing has taken place, and are based on numbers shot per 100 ha. The analysis summarises the year-to-year change within sites as an index of change relative to the start year. This means that the first point of each trend series is set to 1, and subsequent index values of 2, 3, etc. represent a doubling, tripling and so on in number of birds shot (or released) since the start of the series. The error bars around each data point represent 95% confidence limits, and give an idea of the accuracy of the point (the smaller the range that they delimit, the more accurate the plotted value). The histograms in the figures for grey partridge, red-legged partridge and pheasant give an index of the annual numbers of birds released each autumn per 100 ha. Trends in numbers released are calculated only for sites and years when numbers released were reported, so are derived from a subset of sites.