Foundation Nordens Ark has been involved in the Swedish Species Action Plan for the European Green Toad (Bufotes variabilis) since 1995 with the main involvement being head-starting wild collected eggs and tadpoles to toads before release into newly restored historical sites in southern Sweden.

Since 2003 Nordens Ark together with the County Administrative Board of Kalmar has worked to bring back the green toads to the Baltic Island of Öland where the toads were once considered the most common amphibian. During the 20thcentury the population started declining and was subsequently considered locally extinct at the end of 1990s.

The main reason for decline and extinction is not confirmed but is most likely a combination of multiple factors such as eutrophication, lowering of ground water and the draining of wetlands and reduced pasture on shore meadows.

During 2020 Nordens Ark was approached by County Administrative officials and asked to carry out surveys on Öland to confirm the presence of toads in any of the release sites. Green toads are notoriously hard to find. The most widely used method is to listen for males calling during the night in late spring early summer. The other way is simply by doing nightly survey walks to look for toads out hunting or to look for eggs and possibly tadpoles later in the summer.

To maximize the possibility of findings we did two periods. The first one in mid-May revealed bufonid tadpoles in two sites on the north western part of the island and one on the north eastern. Two of these are really interesting as one is in the same site as the first reintroductions between 2003 and 2007, and the other is in the area currently used for release.

Survey period number two was conducted during the last week of May. This also included releasing aprox. 15.000 tadpoles and 27 adult toads in Ottenby nature reserve in the south and another 15.000 tadpoles in Högby hamn nature reserve in the north. All tadpoles are the result of captive breeding at Nordens Ark which means collecting eggs from the wild is no longer needed.

During this period all sites used for releasing toads was visited at least once. In Ottenby nature reserve juvenile green toads were observed out foraging at night. Besides this no other confirmed sightings of green toads were done in any of the locales.

The two sites were bufonid tadpoles were found during the last survey did not show any signs of life with one of the ponds complety dried up. Water samples were collected on the other site and handed over to the County Administrative to test for green toad e-DNA. Water samples was also collected by the County Administrative from the other ponds where tadpoles were found during surveys conducted by staff from Nordens Ark.

By Kristofer Försäter, Foundation Nordens Ark