Nature film about the birds of the fens, the Harriers and Bearded Tits.
WS Man punting on canal with windmill in background, flat grass lands. MS windmill turning. Wide marshland with expanse of water. Shots of reeds. Montague Harriers flying. Two bird watchers. Shots of bird flying and landing. WS man looking for the nest. He waves when he finds it. MS & CU of nest with five eggs. Pan with hen bird as she sweeps down on her nest. The hen preens herself and sits on the eggs.
Swallow tail butterfly on leafs. Another Harrier with five chicks on her nest. The Bearded Tit on his nest in the reeds, the female (unbearded) on the nest. "By now the sun is beating down on the marshes, and she begins to puff and blow in a very unlady like manner". The Harrier spreads her wings over her nest for protection. The female Harrier takes food from the male in mid air and then feeds it to her chicks.
A wild swan flies low over the marshes. More shots of Harriers on the nest, and passing food in the air. Shots of the chicks getting older. Nest of young Sky Larks and mother. Male Harrier leaves baby Sky Lark for his chicks. The chicks in a line on the nest. The keeper punts his boat towards camera, sailing boat and windmill in background. He catches the Harrier chicks, now looking fully grown, and rings their legs. He notes down the numbers. Young Harrier sits on top of reeds.