Birdsong warms a frosty Sussex morning

Waltham Brooks, West Sussex The golden reed along the river's edge vibrates with the pulsing, chattering songs of the warblers

It's a cold morning, and a glistening coating of frost clings to the green surfaces of the vegetation that is still in the shade. The sun is reaching through the trees, and plumes of mist rise from the river's surface as it warms.

The golden reed along the river's edge vibrates with the pulsing, chattering songs of reed warblers and sedge warblers - the sound of a wetland summer. They began to return to Waltham Brooks about a month ago, and now I count more than 30 singing around the reserve. I hear a whirring from a sedge warbler in the brambles next to me, and I turn to watch as it inches up to the top of the bush.