This summer I have enjoyed watching terns, those delightfully elegant summer visitors, firstly at the mouth of the Hampshire Avon then recently at the London Wetland Centre and along the Thames.

Superficially resembling but slightly smaller than black-headed gulls, common terns are daintier and more slimline.

They fly with a distinctive graceful jinking bouncing buoyancy, wingbeats slow, deep and rather exagerated and they very rarely glide like gulls.

With heads tilted downwards peering at the surface of the water they patrol low down along the river margins and once fish fry are spotted the birds execute a somersault in mid-air, twist over and plunge-dive just below the surface to snatch unwary prey.

Earlier in the season before fry had hatched the terns would dive to pick off mayflies.

From mid-June shoals of newly hatched fry swarm along the margins of the Thames at Kingston and indeed all along the river in countless billions, offering not only terns but grebes and predatory fish rich pickings.

The young fish are of many species including chub, roach, dace and bream which all congregate tightly together in defensive linear shoals.

As autumn approaches the common terns fly back to their winter quarters in West Africa the will return to Britain next April to breed.