In 2008 a team of researchers from the Centre for Ecology & Hydrology and Bournemouth University, funded by the Natural Environment Research Council, began a four year research programme into the effects of Mute Swan grazing (Figure 2). This project quantified the effects of swan grazing on the plant community in the River Frome catchment, a chalk stream in southern England. Mute Swan grazing caused substantial reductions in plant cover and biomass, especially in late summer and at high densities swans could eliminate all of the above-ground biomass (Wood et al. 2012). The impacts on plants increased with the numbers of swans present, with non-breeding flocks having greater impacts than breeding pairs and family groups. However, swan impacts on aquatic plant biomass and cover did not persist into the following year, as scouring high-speed flows during winter removed the majority of uneaten plants, and caused swans to move to adjacent pasture fields (Wood et al. in press).