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A scientific study has revealed both polar regions are rapidly heating up
Hundreds of swans that usually come to Norfolk to escape the cold winter in Russia have so far failed to turn up.
Officers at the Wildfowl and Wetlands Trust reserve at Welney said they would have expected to see Bewick swans arrive by now.
Sarah Graves, of the Wildfowl and Wetland Trust, said so far they had not seen one swan.
She said the delay in coming to Norfolk may be due to milder conditions across central and northern Europe.
"Here we are coming to the end of October and we usually have between 100 and 200 Bewick swans, but as yet we haven't seen any," she said.
"They've had some mild conditions in central and northern Europe, so the swans don't see the need to hurry."
She said there were still plenty of other swans at Welney.