Stay up to date with notifications from The Independent

Notifications can be managed in browser preferences.

Frogs that croaked with a Norfolk accent come home Returned to Norfolk,

Matthew Beard
Saturday 13 August 2005 00:00 BST
Comments

Conservationists puzzling over the disappearance from East Anglia of the northern pool frog discovered during research that its croak had taken on a "characteristic inflection" compared to the mating calls of its relatives in Scandinavia.

Before the frog - scientific name Rana lessonae - died out, its mating call was recorded and compared with the others in Norway and Sweden. "In a given area, you have a certain accent because the frogs are used to listening to certain frequencies," said Jim Foster, an amphibian expert with English Nature.

The mating calls, emitted by the male only, differed in the frequency of their chirping, he added.

About 70 of the frogs were released near Thetford yesterday at a secret location to protect them against amphibian collectors tempted to steal specimens. The last known populations lived near the site but surveys in the past 10 years have failed to find the frog there or at other locations.

It is hoped that the frogs, captured in Uppsala, south central Sweden, will live happily among the pools of Norfolk. There are plans to reintroduce it elsewhere.

Spearheaded by English Nature, the partnership project set out to research the frog's English history.

At first it was thought they were a European import but genetic studies pinpointed their origins in East Anglia. Researchers found they formed a distinct northern group along with Norwegian and Swedish pool frogs.

Archaeological digs unearthed pool frog remains around Saxon sites in Ely, Cambridgeshire, and Gosberton in Lincolnshire, but fenland drainage caused the pool frogs to die.

More recently, pool frogs have suffered from the destruction of breeding ponds, water abstraction and lack of habitat management.

Experts said the Norfolk pool frogs had close links to Scandinavian pool frogs because Britain was joined to Scandinavia and continental Europe via a land bridge until around 8,500 years ago. Species such as the pool frog and water vole colonised East Anglia from northern Europe using the natural bridge.

Mr Foster added: "Piecing together what happened to pool frogs has proved to be a real detective story. The frog's distinctive Norfolk accent, the buried remains and genetic studies all provided crucial clues.

"It has taken nearly 10 years of research, involving people across Europe, to get to the bottom of this mystery, and today is the culmination of all that effort."

Join our commenting forum

Join thought-provoking conversations, follow other Independent readers and see their replies

Comments

Thank you for registering

Please refresh the page or navigate to another page on the site to be automatically logged inPlease refresh your browser to be logged in