Almost 500 natterjack toadlets bred in captivity were released into the wild at Castlegregory, Co. Kerry on Monday as part of a conservation project run by the National Parks and Wildlife Service (NPWS) and Fota Wildlife Park.
Unlike previous conservation programmes which relied on spawn gathered from ponds in the wild, the spawn for this breeding programme came from adult toads reared in captivity — a first for Ireland and a significant milestone in the conservation of the species which endures loss of large numbers every summer due to predators and ponds drying out.
Natural mortality rates for the natterjack toadlets can be as high as 90 per cent.
The natterjack toad is one of only three amphibians in Ireland. The other two amphibious species, the common frog and the smooth newt are widespread. But the natterjack toad is restricted to coastal areas of West Kerry where its natural range is restricted to the coastal zones of Castlemaine Harbour and Castlegregory.
The species suffered significant losses in range and population in the early 20th century due to land reclamation and changes in agricultural practises. The latest estimates put the population at less than 10,000 individuals in the wild in Ireland and as a result the species is considered to be endangered. As an endangered species it is protected under the EU’s Habitats Directive.
NPWS efforts to address habitat loss for the toad have focused on pond creation schemes, with some success. Captive rearing plays an important role in the conservation of the natterjacks and more than 6,000 individuals have been successfully released into the wild to date.
This year has, however, been challenging for the toads, with the dry spring and summer meaning that spawning in the wild was very limited.
Through this project, staff from NPWS collect toad spawn and tadpoles from ponds in the wild and transport them to Fota where they are carefully looked after in special holding tanks over the summer months. Following metamorphosis, the resulting toadlets are then returned to the species’ native range in Kerry.
For the first time, the project also produced its own toadlets this year. A small number of mature natterjacks were held in Fota and these produced spawn (captive breeding), providing a potentially important boost to the conservation efforts to save the species.
Minister for Heritage, Malcolm Noonan said the project was “a fantastic example of scientists, conservationists and communities coming together to protect this rare amphibian and the habitat it depends on”.
Under a new scheme local farmers can benefit from a results-based scheme specifically for Natterjack toads, Mr Noonan said. “This scheme will pay farmers to manage their land in a way that helps ensure the conservation of this endangered species, and I hope that everyone will get involved,” he added.
Dr Sean McKeown director of Fota Wildlife Park said predation of natterjack tadpoles was a significant cause of mortality in the wild. “To avoid predators, natterjacks typically breed in shallow sunny ponds. However, these ponds are susceptible to drying up early. Desiccation of breeding ponds before metamorphosis accounts for significant mortality in Irish natterjacks in some years” he said.
Dr Ferdia Marnell, the amphibian specialist with the NPWS who has been overseeing the project said “the natterjack is a boom or bust species. This year was not one of the good ones.”
