AS an estimated 16 million migrant birds make their way to Britain, people across the world will be celebrating World Migratory Bird Day this weekend to mark the incredible journeys that many of these birds make as they migrate to their summer breeding grounds.

World Migratory Bird Day will take place on 9-10 May. Over the next few weeks an estimated 16 million birds will arrive in the UK, after spending the winter as far away as South Africa.

For some birds, like the common tern, a dainty gull-like bird with a black cap and long forked tail, the journey here will involve a gargantuan effort, flying up the west coast of Africa, across the mouth of the Mediterranean, along the coasts of Iberia and France, and finally a relatively short hop to their nest site, which could be on a gravel pit in Yorkshire.

The total distance covered will be around 4,500km and will take approximately 20 days . This route is known because of the efforts of volunteer ringers, who give their time freely to trap these birds and fit them with unique metal rings under license to the British Trust for Ornithology. And this year bird ringing in Britain marks its 100th anniversary.

The majority of Common Terns that have been ringed in this country are found during the winter in Ghana and Senegal. However, one exceptional individual ringed in Northern Ireland was found dead in Victoria, Australia, 17,641 km from where it was ringed!