The migration patterns of nightingales are still largely a mystery to scientists, so the British Trust for Ornithology has teamed up with Anglian Water to fit the tags to shed more light on the subject. Over the next two weeks, the BTO and Anglian Water, who have been working together on this project for two years, will be attaching the new lightweight tags to the birds at Grafham Water reserve, where the habitat is managed by the Bedfordshire, Cambridgeshire and Northamptonshire Wildlife Trusts. The tags weigh one gram each and scientists have carried out tests to ensure they do not affect the welfare of the birds. The BTOs Paul Stancliffe said: Being able to track these birds as they move between Africa and Grafham Water, seeing the routes they take, where they stop to rest and feed, and for how long, would have been the thing of dreams only a few years ago. Anglian Water wildlife scientist, Mike Drew, added: Alongside the BTO, we have already gained real insights into the migration of this enigmatic bird. As the nightingale population in the UK continues to fall, habitat degradation has been cited as a large part of the problem. To coincide with this years tagging operation, the BTO has just released its guide to managing habitats for nightingales. A lot of land isnt managed in the way it used to be, said Wildlife Trust BCN officer Aidan Matthews. At Grafham we clear the scrub down until it lays flat. This keeps it really dense and really helps them. The resulting data wont be available until next spring, but the detailed route maps it produces should prove fascinating.