England's biggest puffin colony is bouncing back after numbers of breeding pairs tumbled in the last major survey, the National Trust said today.
Small surveys conducted by wardens on the islands off the coast of Northumbria suggest the birds' numbers have risen by 5% in each of the past two years, but researchers say they do not know what caused the last crash – and another is possible.
They have fitted puffins with "sat-nav" technology to track the birds' movements during the breeding season and throughout long winters at sea as part of efforts to protect the birds.
Richard Bevan from the University of Newcastle has used small GPS trackers temporarily glued on to the back of 12 birds to track their foraging habits, which have revealed puffins raising chicks in burrows on Brownsman Island are heading out to feeding hotspots 20 miles out to sea.
The adult puffins can make several journeys a day, returning to their young with up to 60 small fish known as sand eels in their distinctive orange beaks, the island's wardens said.
Farne Island's head warden, David Steel, said information about where the puffins are foraging for food could help protect habitats that are important for them as part of plans to create conservation zones around the UK's seas.
"If you're looking to protect areas, if you can start pinpointing if the birds are going to a certain area, then you can start protecting those areas," he said.
While the Farne Islands, where the birds breed, were "protected to the hilt", there was also a need to protect the areas in which they were feeding, he added.
Bevan said working out where they were during the winter – and particularly in the run-up to the breeding season when the females need to get into top condition to breed – could help identify what might be going wrong in those areas to lead to reductions in sea bird populations.A spokesman for the environment department said: "The data on this species will be really useful for the ongoing work on marine conservation zones.
"These areas will help protect our marine habitats and species, from the rare and threatened to the more common."