Maud Island Frog
(Leiopelma pakeka)
Until a genetic analysis in 1998, this species was thought to be a subpopulation of Hamilton’s frog. The Maud Island frog is part of the world’s most primitive frog lineage, which has been evolving independently for over 200 million years. It is active at night and ground-dwelling, breeding on land. The male guards the eggs in moist nests, and carries the froglets on his back for several weeks whilst they develop. It is primarily threatened by a virulent fungal disease (chytridiomycosis), and introduced predators, such as black rats. This frog was introduced to nearby Motuara Island as part of a conservation project to expand the range of this species in 1997.
Urgent Conservation Actions
Regular population monitoring (both of numbers and disease); habitat restoration programme; prevention of accidental introduction/colonisation of predators.
Maud Island in the Marlborough Sounds, New Zealand. Introduced to Motuara Island in 1997.
Populations of the Maud Island frog were previously considered to be Hamilton’s frog, but were subsequently described as a new species in 1998 as a result of genetic analyses.

Research has shown that New Zealand frogs may find each other and/or communicate using visual clues or perhaps through pheromones. Studies have revealed this behaviour in two species of New Zealand frog – the Maud Island frog can respond to olfactory cues (messages detected through their sense of smell) in faeces, and Hochstetter’s frog (EDGE rank 38) prefers its own odour to the smell of unfamiliar members of the same species. This system probably developed in the absence of being able to communicate via sound, because New Zealand frogs lack both eardrums and developed vocal chords.
Evolutionary Distinctiveness
Order: Anura
Family: Leiopelmatidae
The prehistoric New Zealand frogs (of the family Leiopelmatidae) are the most ancient and primitive frogs in the world, diverging from all other frog and toad lineages over 200 million years ago in the former southern supercontinent of Gondwana. The ancestor of these species actually colonised New Zealand over 80 million years ago, when it was still part of the Gondwana, and the Leiopelmatidae shares a similar biogeographic distribution to several other ancient plant and animal groups, such as southern beeches, tuatara, and the giant extinct moa. This means New Zealand frogs started to evolve independently as a lineage before the formation of the Atlantic Ocean, over 50 million years before the first bird appeared in the fossil record. They are part of a small suborder of frogs called the “archaeobatrachia” or ancient frogs. The archeobatrachia comprise less than 7% of all of the frogs and toads, including some of the most evolutionarily distinct amphibian species. Each one therefore represents a disproportionately high amout of distinct evolutionay history in today’s biodiversity.

The four surviving species of New Zealand frog are found only in New Zealand, and these species are regarded as “living fossils” since they are very similar to frog fossils found in Queensland, Australia from the late Jurassic period around 150 million years ago. Fossil records actually show that New Zealand had seven leiopelmatid frog species just 1000–2000 years ago. The scientific names of the three extinct species are Leiopelma auroraensis, Leiopelma markhami and Leiopelma waitomoensis, which was previously the largest species of New Zealand frog at a total length of 100 mm – over twice the size of the largest New Zealand frog species alive today. These species were considerably larger, squat and toad-like leiopelmatids, which probably walked rather than hopped, and were found both on New Zealand’s North Island (L. markhami and L. waitomesis) and South Island (L. markhami and L. aurorensis). It is likely that all were wiped out by the (presumably accidental) introduction of the Pacific rat (Rattus exulans) by Polynesian settlers less than 1,000 years ago. The surviving species are restricted to the vicinity of North Island – Archey’s New Zealand frog and Hochstetter’s New Zealand frog occur only on the North Island, while the Maud Island frog and Hamilton’s frog are restricted to Maud Island in the Marlborough Sounds and Stephen’s Island in Cook Strait.

A primitive feature retained by Leiopelma frogs is their tail-wagging muscles (known scientifically as the caudalipuboischiotibialis muscles), although they no longer have a tail to wag. Other unique or unusual features of these frogs include the presence of elongate pieces of cartilage in the muscles of the abdomen (also called “inscriptional ribs”), round pupils, and an abnormally high number of vertebrae, or back bones – they have 9 presacral vertebrae with atypical concave ends, instead of the eight found in all other living frogs except their closest relatives, the tailed frogs from north-western U.S.A and Canada. Also, they cannot croak like most other species of frog (instead letting out a thin high-pitched squeak) because eardrums and vocal sacs have never developed in this group of frogs. Where aquatic in nature, they also swim differently to all other frogs (apart from the tailed frogs), in that they use alternate leg kicks which cause their heads to move from side to side during swimming in a rather energy inefficient way. It is thought that New Zealand frogs began their terrestrial (or ground dwelling) lifestyle before advanced swimming evolved in frogs. In keeping with their place as four of the world’s most primitive frogs, the way in which the skull remodels during metamorphosis within the egg, where the tadpole changes into a froglet, is said to be intermediate between a salamander and the tailed frogs (which are the next most primitive frogs on earth).

The Maud Island frog was previously considered to be a sub-population of Hamilton’s frog (the Maud Island frog (Leiopelma hamiltoni – EDGE rank 17), but were subsequently described as a new species in 1998.
These frogs are very well-camouflaged, the overall colouration being brown, ranging from a light tan to almost black. They have black patterning over their backs and faces and a glandular ridge running along their body from behind the eye. The fingers and toes are completely unwebbed, and they are very similar to Hamilton’s frog (EDGE rank 17), which is why they were classified as the same species until genetic analyses in 1998. However, the Maud Island frog is slightly smaller than Hamilton’s frog, measuring up to about 47 mm in total length. It is very difficult to differentiate between the males and females of this species because they are more or less identical in size and appearance.
This species is nocturnal (night-active), preferring cool, misty evenings. and are particularly active above ground when the temperature is between 8-14ºC. They seem to be territorial and tend to stay with a 5m radius for years at a time. They are very long-lived frogs, with some individuals being found thirty years after they were first marked. They catch their prey by grabbing it with their mouth as they do not flick their tongues out like many other frogs species.

Although these frogs have never been observed breeding in the wild, close observations have been made of their breeding behaviours by Dr. Ben Bell of Victoria University, who kept breeding Maud Island frogs in an enclosure in his garden. 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 hatch. There is no free-swimming tadpole stage and the young climb onto the back of the male and continue their development there. During this time they remain fairly inactive. Although independent of water sources for breeding and ground dwelling in nature, this species is very dependent on a damp environment, and will quickly dehydrate and die if placed in a dry place.

These frogs are very cryptically coloured, relying on camouflage as their main line of defense against predators. The Maud Island frog, like all other native New Zealand frogs, does not exhibit a breeding call. This is because they are a primitive frog species that do not possess vocal chords or eardrums. However, they are known to squeak or chirp when annoyed, distressed, or during sexual activity. Because of the absence of well developed vocal sac, the sounds they produce depend upon resonance frequencies in head and body, rather than the vibration frequency of vocal chords.
The Maud Island frog prefers rocky areas under a full canopy of native trees. It can be found on coastal forest, mostly in deep boulder banks on lower slopes.
This species only occurs naturally on Maud Island in the Marlborough Sounds, New Zealand. Maud Island is small, totaling just 309 hectares of land. This species was also introduced to another predator-free island in the Sounds area called Motuara Island, and further translocations are planned by the Department of Conservation to other areas to expand the range of this species.
Population Estimate
The main population of this species occurs on the isolated Maud island, although it has also been introduced to nearby Motuara Island as part of a conservation project to expand the range of this species in 1997, when 300 individuals were translocated The population estimate for this species on Maud Island is estimated at 27,500-39,500 individuals in a 16 hectare forest remnant. There are approximately 200 individuals estimated on Motuara Island.
Population Trend
The population of the Maud Island frog is thought to be stable by the IUCN Red List of Threatened Species.
The Maud Island frog is listed as Vulnerable in the IUCN Red List of Threatened Species because it is known from only a single location.
Introduced mammalian predators (e.g. the black rat, Rattus rattus, and the stoat, Mustela erminea) are a major threat to the survival of this species. Another rpotential threat is disease, especially chytridiomycosis which has been recently identified in the closely related Archey’s frog in the North Island of New Zealand. Chytridiomycosis is caused by the chytrid fungus (Batrachochytrium dendrobatidis) that has been reported as a frog pathogen in many areas of the world. Chytrid fungus infection was first identified in Archey’s frog in September 2001 and has been the major causal factor in a number of amphibian extinctions worldwide.

Furthermore, the small population and miniscule range of this species make it vulnerable to sudden decline and extinction brought on by sudden climatic change, or natural population fluctuations.
Conservation Underway
New Zealand has been protecting its indigenous amphibian species since 1921, when legislation was passed making it an offence to harm or remove frogs from their environment.

In 1997, 300 Maud Island frogs were translocation to the predator-free Motuara Island 25 km away in the Queen Charlotte Sound. Previously, 100 individuals had been moved to a new site on Maud Island in 1984-85. These translocation were made, to reduce the possibility of an ecological disaster wiping out the entire species in its original 25 range.

The New Zealand Department of Conservation (DOC), acting through its Native Frog Recovery Group and Native Frog Recovery Plan, administers conservation management of the Maud Island frog and permits appropriate research on this species. In 2006 100 frogs were translocated to Long Island (near Motuara) in Queen Charlotte Sound, and all of these new populations are being actively monitored by DOC.

Conservation actions in the wild also consist of protecting habitat and removing mammalian predators (such as rats and mice) from frog habitat, or ensuring that they do not gain or increase access to existing frog populations. Further introduced frog species (there are already 3 species of non-native Australian treefrogs established in New Zealand) may out-compete native New Zealand frogs and/or introduce more virulent diseases, so it is also a priority of the DOC to ensure against the accidental introduction of other amphibian species.
Conservation Proposed
Regular population monitoring (both of numbers and disease) and a habitat restoration programme are needed to protect the remaining populations of this species, both natural and introduced. Prevention of accidental colonisation of Maud Island or Motuara Island by introduced mammalian predators must be ensured. It would also be beneficial to establish a captive breeding programme for this species as a further insurance policy against future ecological disasters.
Associated EDGE Community members

Phil is an expert on amphibian breeding behaviour

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