Country diary: dancing and diving, a dipper braves the ice-cold river

Black Banks Plantation, Weardale, County Durham Maintenance of insulating plumage is vital for a bird whose survival depends on feeding underwater

It was a morning of brittle beauty, the best kind of winter day. Last night's magical transformation remained intact; rusty-brown bracken fronds fringed with frost crystals and ice-encrusted leaves that crunched underfoot. No hint of a thaw yet; the low elevation of the sun had left this side of the riverbank in deep shadow. The cold air stung our cheeks.

In still pools beside the river, the 6mm-thick ice must have frozen gradually overnight, from the edges inwards as the water level dropped, creating concentric oval patterns with elegant art nouveau flourishes around their margins. In a few places, ice sheets remained suspended between the trunks of alders, creaking and groaning when the wind disturbed their branches.