Cholsey Marsh | Berks, Bucks & Oxon Wildlife TrustA tranquil riverside marsh with great crested grebe, warblers and a colony of the nationally rare Desmoulin's whorl snail.A tranquil riverside marsh with great crested grebe, warblers and a colony of the nationally rare Desmoulin's whorl snail. Rare haven Once common, riverside marshes such as this are now scarce because of large-scale drainage for farming. Cholsey Marsh https://www.bbowt.org.uk/reserves/Cholsey-Marsh