Description These frogs are very cryptically coloured, relying on camouflage as their main line of defence. Their overall colouration is brown (ranging from light tan to almost black), with black patterning over their backs and faces. They do not have an eardrum, but do have a glandular ridge running along their body from behind the eye. They do not produce loud mating calls, although they can produce a faint squeak when molested. There is no webbing on their feet or hands. They are very similar to Leiopelma hamiltoni and up until recently (Bell et al. 1998) they were thought to be the same species.
However, Holyoake et al. (2001) using molecular techniques, found only slight variation between the two taxa and although favor keeping them as one species, they suggest treating them as evolutionarily significant units (ESUs). These frogs look almost identical to Leiopelma hamiltoni but are slightly smaller (about 47 mm SVL). L. pakeka is monomorphic and therefore very difficult to sex.
This species only occurs naturally on Maud Island in the central Marlborough Sounds, New Zealand. This is a small, relatively sheltered island of 309 hectares of moderate to steep hill country. Maud Island supports a healthy population of around 19,000 Leiopelma pakeka individuals in broadleaf forest. In 1984-1985, individuals were translocated to another site on Maud Island, and in 1997, to Motuara Island, another predator-free island in the Sounds area (Tocher and Newman 1997; Bell et al. 2004).
L. pakeka prefer rocky substrates under a full canopy of native trees (Bell 1995).
Life History, Abundance, Activity, and Special Behaviors
These frogs prefer cool misty evenings and are particularly active above ground when the temperature is between 8 and 14C. They show considerable site fidelity and tend to stay with a 5m radius for years at a time, as well as to shelter within specific retreat sites (Bell 1994; Bell 1997; Bell 1978). They are very long lived with some individuals being found thirty years after they were marked; an average life expectancy of 33 years has been calculated (B. D. Bell, pers. comm.; Bell et al. 2004).
They are nocturnal and catch their prey by grabbing it with their mouth as they do not flick their tongues out like many other frogs. Although these frogs have never been observed breeding in the wild, Dr Ben Bell of Victoria University has made some observations from an enclosure in his garden (Bell 2002). He discovered that in captivity frogs lay 1-19 eggs in December in moist depressions under logs, rocks or vegetation. The eggs are guarded by the male and take 14-21 weeks for the eggs to develop. There is no free-swimming tadpole stage and the young climb onto the dorsal surface of the male and continue their development there. During this time they remain fairly inactive.
During tadpole development, the developing forelimbs are large and completely exposed at all larval stages, with only the bases of the forelimb covered by the opercular fold. The L. pakeka tadpole has a ventral mouth but has no oral disc, denticles, or papillae. A large tongue pad is present in the stage 31 embryo. Pigmentation is developed from about stage 33 onwards (Bell and Wassersug 2003).
In 1984-1985, 100 Leiopelma pakeka were translocated in two batches from Maud Island to a new site 0.5 km away, also on Maud Island. Recapture studies nearly 20 years later, in 2003, found 70 of the original 100 individual frogs, plus 35 young recruits into the population. Frogs in the earlier batch settled closer to the release site than did those released a year later (Bell et al. 2004).
In 1997, the first island-to-island translocation of Leiopelma pakeka was carried out, from Maud Island to Motuara Island, which lies 33 km SE in Queen Charlotte Sound (Tocher and Newman 1997; Bell et al. 2004).
Trends and Threats This species occurs on two isolated islands (Maud Island and Motuara Island) and appears to be stable in population (Bell and Bell 1994). Frogs from the original Maud Island population were translocated in 1984 and again in 1985 to another site also on Maud Island (Boat Bay; Bell et al. 2004). A translocation to a different island (Motuara Island, in Queen Charlotte Sound) was carried out in 1997 (Tocher and Newman 1997; Bell et al. 2004). Despite the Maud Island populations appearing to be stable, the Boat Bay population is small and both the Boat Bay population and the original source Maud Island population have declined in condition over time (Bell et al. 2004). Also, very little genetic variation appears to be present (Bell et al. 1998).
The species remains conservation dependent and strict measures are in place to prevent the spread of any pathogens or predators to the island habitats.
Possible reasons for amphibian decline
General habitat alteration and loss Habitat modification from deforestation, or logging related activities Intensified agriculture or grazing Habitat fragmentation Predators (natural or introduced) Loss of genetic diversity from small population phenomena
Citation: AmphibiaWeb: Information on
amphibian biology and conservation. [web application]. 2013. Berkeley, California:
AmphibiaWeb.
Available: http://amphibiaweb.org/.
(Accessed: May 19, 2013).
