ONE of the world’s longest-running wildlife projects based in Gloucestershire is turning 50 today.

The Bewick’s swan study began at the Slimbridge Wildfowl and Wetlands Trust (WWT) in 1964.

It began with simple observations as founder Sir Peter Scott and his family encouraged wild Bewick’s swans wintering on the salt marshes near Slimbridge to visit the lake in front of their house.

They noticed that the birds had unique black and yellow bill patterns, which enabled individuals to be identified.

When the swans returned the following winter the family recognised familiar faces in the flock.

Since then the natural markings have continued to be used as a powerful tool for studying the birds.

The research has developed into a sophisticated global study involving scientists and collaborators across the birds’ migratory routes.

More than 9,000 different swans have been identified and a huge amount of valuable data has been collected about the birds’ social behaviour, population dynamics and choice of breeding grounds.

The Bewick’s swan is the smallest of the northern migratory swan species and breeds in Arctic Russia.

The European population rose to a peak of 29,000 in the mid-1990s but has declined by around one-third in recent years as the species has been threatened by habitat loss and climate change.

Collisions with power lines and wind turbines have also caused numbers to drop. This winter WWT is fitting transmitters to a small number of birds to track their exact flight route and height across the North Sea, to inform plans for offshore windfarms.