Many of our garden birds, such as House Sparrows and Starlings, are busy building their nests in April. Some others, like Blue Tits and Great Tits, are laying and incubating their eggs, hopefully timing the hatching of their young with an abundance of caterpillars. Carrion crows and Magpies are repairing last year's nest. Summer visitors are also returning.
Sand Martins are the first hirundines to arrive in Britain, often in mid-March, followed by House Martins and Swallows. Swifts, which aren't actually hirundines, arrive last in late April or early May. All are returning from wintering grounds in southern Europe and Africa to breed in the UK, where there is a relative abundance of insects to feed their young.
Migration reaches its peak this month with hirundines, warblers, flycatchers and Cuckoos arriving on our shores. Why not join the on-line BTO BirdTrack survey and help scientists understand more about migration.