Anglesey's Very Own Invasive Species - Crossing The Menai Strait.

 Island fights back grey squirrel invasion

For a decade only native red squirrels lived on Wales' Anglesey island, following a massive cull of their invasive grey cousins. But now the greys are somehow getting back across the Menai Strait. Dr Craig Shuttleworth is on a mission to stop them.Video produced by Justin Rowlatt and Gwyndaf Hughes.