Winter worries

spend the next nine months without making landfall. And it is becoming increasingly clear that very little is known about the birds during this time. As they breed only above 50 degrees latitude, they are considered cold-water birds, but researchers working with puffins breeding at England's largest colony on the Farne Islands are concerned about their winter environment as there has recently been an alarming fall in the number of adults returning. So this summer, researchers at Newcastle University working with wardens from the National Trust, have been fitting transmitting devices to chicks that can be tracked by GPS to help researchers discover why their numbers are falling during the long winter months. Scientists do not know where the birds spend the winter, so they hope the devices will help them pinpoint the location and help explain a dramatic decline in numbers over the past five years. The researchers have glued the devices to the birds' feathers and they will drop off after a week or two. But researchers hope this will be enough time to locate their wintering sites. A survey carried out in summer 2008 found that numbers were down a third to 36,500 from 55,600 recorded in the previous survey in 2003. The puffins will also be weighed and measured to make sure the tags do not affect their feeding habits. In addition, the puffins will be fitted with small time-depth recorders, which will help scientists find out more about the way puffins dive in search of food. The researchers were also keen to determine that there was sufficient local food for the breeding birds. John Walton, the National Trust Farne Island manager, said that Newcastle University had carried experimental trawls and had found abundant sand eels — the staple food species for both adults and chicks. " Puffins on the islands produce more than enough young to sustain or grow the population. " The recorders will give detailed information about how often and how deeply they dive, and at what sea temperatures — helping to explain how puffins at sea might be affected by climate change and possible changes in sea temperature. " Technological developments now mean that we are getting closer to finding the pieces of the jigsaw to help solve the puffin puzzle, " says Richard Bevan from Newcastle University. " The new data will help explain what the puffins are doing when they …