Britain's biggest butterfly threatened by rising seas

New charity warns Britain’s largest butterfly could be lost within four decades as rising seas turn its habitat into saltmarsh

Patrick Barkham

Fri 29 Jun 2018 12.27 BSTLast modified on Fri 29 Jun 201813.40 BST

Britain’s biggest butterfly, the swallowtail, could become extinct within four decades because of rising sea levels, a new charity has warned.

New inland habitat needs to be created for the swallowtail because rising seas are predicted to turn much of its current home, the Norfolk Broads, into saltmarshes later this century.

The British swallowtail caterpillar’s only food plant, milk parsley, cannot survive in saltwater, and so the plant and the butterfly will need to be translocated to the Cambridgeshire fens, according to butterfly experts.

“At least 90% of the current swallowtail breeding sites will become salt marsh with a sea level rise of 50cm,” said Mark Collins, chair of the Swallowtail and Birdwing Butterfly Trust, a new charity working to save the 500 swallowtail and birdwing butterfly species worldwide. “We could be looking at 30 or 40 years and these sites will be gone, given the rate of sea-level rise and also tidal surges and ‘salination events’, where saltwater comes rushing up the Broads’ rivers.”

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