Snails on the menu at Crymlyn Burrows

Song Thushes will occasionally eat snails and it is well known that they use rocks as 'anvils' in order to smash the shells open. But I have never seen an anvil-technique like this one before. The recent very cold weather has forced large numbers of Song Thrushes to our coast in search of food. Near where I took this photo on the dunes at Crymlyn Burrows there were 40+ Song Thrushes within a 50m radius along with smaller numbers of Blackbirds and Redwings.
The recent cold temperatures have frozen the dunes solid and the thrushes have been making use of the rock-hard, frozen sand to smash the shells, in the absence of their traditional anvils.
Many snails are sheltering at the base of Marram Grass (Ammophila arenaria) but the Song Thrushes have discovered this and the shell fragments that can be seen scattered along the paths in the dunes are evidence. It will be interesting to find out whether this will have any effects on the dune system's vegetation come the summer?