We're all used to seeing and enjoying the birds in the summer in our gardens but winter is an equally fascinating because of the flocks of birds that arrive in Wales from their nesting and breeding grounds. At this time of year at the RSPB nature reserve at Ynys-Hir, near Machynlleth a flock of around 60 Greenland white-fronted geese are overwintering and will be in residence there until the third week of April. This is the only flock in England and Wales and they return every year to this traditiona spot on the Dovey estuary to feed on the saltmarches and lowland wet grassland. Mel Doel meets the wardens and volunteers working on the reserve and finds out what's being done to conserve the natural environment.