The Maud Island population were named as a separate species (Leiopelma pakeka) in 1998 as a result of allozyme DNA studies, which suggested they were a distinct species. Further genetic studies ensued, it was later postulated that the allozyme data reflected a genetic bottleneck (resulting from the isolation and small size of the populations), and the two groups are now considered to be a single species.
Description
The largest of New Zealand’s native frogs, with females reaching SVLs (snout-vent-lengths) of up to 49mm, with males reaching SVLs of 43mm. Dorsal (upper) surfaces are light to dark brown, often with a pattern of black patches; ventral (lower) surfaces are light brown. Hind feet have almost no webbing, an adaptation to living on rocky ground.
Life expectancy
Largely unknown.
Distribution
Hamilton’s frog were once spread from Waikato to Punakaiki, however, now only found in the Marlborough Sounds area and within mainland sanctuaries such as Zealandia.
Ecology and habitat
A nocturnal species, Hamilton’s frog inhabit rocky areas among logs and moss. The species can climb several meters in trees and ferns.
Social structure
Largely unknown.
Breeding biology
Tadpoles remain within the egg. Eggs are laid in damp recesses on the ground, in trees, or in the crown of tree ferns.
Diet
Invertebrates.
Disease
Hamilton’s frog are at risk of diseases such as amphibian chytrid fungus.
Conservation
Hamilton’s frog are listed as ‘vulnerable’ on the IUCN red list. In the 2013 threat classification series DOC listed the Maud Island and Hamilton Island populations separately with Leiopelma hamiltoni categorised as ‘nationally critical’ and Leiopelma pakeka as ‘nationally vulnerable’ (both groups are now considered to be one species).
Threats to Hamilton’s frog include introduced predators, disease, habitat change and destruction. Intra and inter island translocations took place in 1992, 2004 and 2006. On Stephens Island tuatara were preceived to be a threat to Hamilton’s frog due to their abundance and the small area the frogs were occupying. In 2006 a group of 21 frogs were translocated from Maud Island to Zealandia Sanctuary.
References
- Cash, B., & Gaze, P. (2008). A history of wildlife translocations in the Marlborough Sounds. DOC: Wellington.
- Jewell, T. (2011). A photographic guide to reptiles and amphibians of New Zealand. Auckland: New Holland Publishing Ltd.
- Newman, D.G., Bell, B.D., Bishop, P.J., Burns, R.J., Haigh, A., & Hitchmough, R.A. (2013). Conservation status of New Zealand frogs, 2013: In New Zealand Threat Classification Series 5. DOC: Wellington.