The green toad was at one time fairly common in coastal areas in the south and south-east of Sweden. Today, the species is our most endangered amphibian and is classified on the Red List as Critically Endangered.
There are many reasons for the species’ decline, including eutrophication and overgrowth of once nutrient-poor open land, lowering of groundwater and drainage of spawning grounds, deteriorating water quality, and the introduction of fish and crayfish in many ponds. Following inventories and restoration of a number of habitats, breeding and releases have taken place at many sites within the species’ former known range. However, the results have not been as good as for many other threatened amphibians released after rearing in different facilities.
Nordens Ark has been involved for many years in conservation of the green toad. We have successfully reared larvae, newly metamorphosed and adult toads which were released in Skåne and Blekinge, and on Öland and Gotland.
From 2009 to 2014, between 200 and 400 green toads (a mixture of adults and youngsters) were released each year – altogether about 1,600 individuals. The releases were concentrated on Öland, principally the southern headland, and a bird sanctuary near Högbyhamn on the island’s north-eastern side. Many sightings have since been reported and spawning has occurred repeatedly. This means there is now a small but viable population on Öland’s southern tip. In Högbyhamn, two over-wintering places were created to make sure that the released toads would get through the winter. At both sites on Öland, restorations have taken place with new shallow spawning grounds.
All the toads were raised at Nordens Ark in a sterile quarantine area. Eggs and larvae were kept indoors to maximise survival. The transformed baby toads were then gradually introduced to a more natural environment outdoors and fed with a variety of small insects. Before leaving Nordens Ark, they were tested and declared free of the fungal disease ‘chytrid fungus’ and Ranavirus, and were photographed to enable us to identify them in the event of future sightings.
Green toad releases are a collaborative venture between Nordens Ark Foundation and Kalmar county administrative board and are supported by the Swedish Postcode Lottery.