Numbers, densities and distribution of mallards released for shooting in the UK over the last 20 years

Quantifying numbers of birds released for shooting is an important step towards understanding the ecological consequences of releasing. For Mallard, this has become urgent with the recent rise of Highly Pathogenic Avian Influenza (HPAI). By adapting a previous approach to generating UK-level estimates of numbers of huntable birds shot using the Game and Wildlife Conservation Trust’s National Gamebag Census (Aebischer NJ (2019) Fifty-year trends in UK hunting bags of birds and mammals, and calibrated estimation of national bag size, using GWCT’s National Gamebag Census. Eur J Wildl Res 65:64. https://doi.org/10.1007/s10344-019-1299-x), the number of Mallards released annually in the UK rose from 870,000 in 2004 to 1.3 million in 2022. Mallards were shot at just over half of NGC sites; of those a fifth released Mallards for shooting, accounting for 87% of the total Mallard bag in 2022. In that year, mean release size was 792 (median 300) and mean release density was 1.39 birds/ha (median 0.52). One fifth of release sites released over 1000 birds each, mostly in southern England and Scotland, corresponding to just 2% of UK shoots. The low percentage combined with low dispersal of released Mallards suggests that scope for them to spread disease is limited, and that any spread is more likely to occur by infection from and transmission to wild birds on passage than from dispersed released ducks.