Driving over Kingston bridge one foggy morning in late February, I was thinking about the swallows that nest below me along the riverside and looking forward to their return for the summer.

For, as February draws to a close swallows (male pictured) , having spent our winter sunning themselves among the Capetown reed beds are beginning their epic hazardous six week journey from South Africa back to Britain.

They overfly fourteen countries and the Sahara desert en route beginning at Namibia thence Zambia; Congo; Cameroon; Nigeria; Algeria; Morocco; Gibraltar; Spain; France then finally across the English channel to the British Isles.

Males arrive first looking resplendent in fresh plumage and begin consolidating territories, often the same ones and nesting sites used in previous years. Females fly in a little later but they should all be back by the beginning of April.

Arriving at the same time as the swallows or sometimes a little earlier are the house martins, resembling swallows in some ways but smaller, dumpier, with shorter wings and tails.

They too nest along Kingston riverside and often mix with the swallows as they hunt insects over the river. Whereas swallows skim the water house martins hunt at slightly higher levels as do sand martins but they have declined along the river in recent years although good numbers nest at the London Wetland Centre every season.