Rare Hamilton’s frog species released into the wild in Zealandia

Hamilton’s frog is one of the most endangered frogs in the world.
photo: Hayley May

Wellington Ecological Reserve has released a group of rare captive-bred Perektua back into the wild.

Hamilton’s frog is one of three species of frog native to New Zealandand is one of the most endangered species in the world.

The frog is listed as “Threatened – Nationally Vulnerable” with no other wild populations left on the mainland as they are severely affected by habitat loss, disease and predation.

After 20 years of monitoring and research, the last of the captive population were released from Zealandia’s enclosure last week, and a boardwalk built to protect them from human trampling was officially opened.

The boardwalk is designed to prevent frogs from climbing it because frogs are small, well camouflaged, and silent.

The decision was made in partnership with the Department of Conservation’s frog recovery team and kaitiaki Ngāti Kuia and Taranaki Whānui ki Te Upoko o Te Ika.

Zealandia conservation and restoration general manager Joe Ledington said the research showed the species could survive in the presence of kiwis and mice, which was vital for future populations to be established.

“Now that the species is fully wild, we can also explore complex issues that will have further implications for the conservation of the species at a national level.”

Due to their sensitive skin, frogs are extremely vulnerable to disease, pollution and environmental damage.

Introduced mammalian predators also pose a serious threat to these endangered species.

Hamilton frogs from Te Pākeka/Maud Island and a captive population at the University of Canterbury were transferred to mainland Zealand in 2005. They were placed in three fully enclosed enclosures as it was not known how they would interact with the kiwi and small number of rats present in the reserve.

In 2012, a further 100 frogs were placed into an inner enclosure to protect them from kiwis, to assess how they would fare in the face of rats, while also protecting them from local birds.

Some frogs have spread outside the fence and surveys have shown they are doing well in the presence of kiwis and mice.

Surveys conducted in Zealandia over the past few years have found frogs of all sizes, including pregnant females and young frogs in both captive and wild populations, suggesting the population is doing well.

The newly released Perpetua population will continue to be monitored by Zealandia as they disperse.