Download The Reptiles and Frogs of Maungatautari

The reptiles and frogs of Maungatautari
By Chris Smuts-Kennedy
NZ has permanently lost its largest herbivores, the moa. They were our ‘ecosystem
engineers’, largely shaping the botanical landscape into which all other species fitted in their
various ways. Their primary ecological role can never be refilled, so our reconstructed
faunal communities on the mainland will always be in a very different botanical setting,
however ‘natural’ we might like to think they look. This is indeed the age of ‘novel
ecosystems’ – even our ‘restored’ ones. But we can only do what we can only do, and
Maungatautari can certainly be about as good as any such restoration can get on the NZ
mainland.
The pre-human fauna of New Zealand is often viewed as being predominated by birds, and
there is some truth in that, with birds (and indeed some insects) taking on many ecological
roles that in other places are performed by mammals. But there was also a significant NZ
‘herpetofauna’, with probably more than 100 lizard species, half a dozen frog species, and 2
tuatara species. Reptiles performed important ecosystem services including pollination (via
nectar feeding) and seed dispersal (some NZ plants have evolved to produce fruits which are
detected and consumed mostly by lizards). Tuatara were mid/high-level predators, and
research is increasingly discovering the ecological importance of such predation. In some
USA ecosystems where species like bears, wolves and cougars have been removed,
progressive ecosystem degradation has been observed. And where those top predators
have been reintroduced (e.g. wolves in Yellowstone), the ecosystem has returned to a much
healthier functional state. Co-evolved native predators are normally good, introduced
exotic predators are mostly not good.
While many NZ ‘keystone’ bird species are now extinct (the large herbivores i.e. moa, and
the large predators Haast’s eagle, Forbes’ harrier, adzebill and laughing owl), the good news
is that very few NZ lizards and no tuatara are totally extinct (we’ve probably lost only 2 skink
and one gecko species – but we have lost half our frog species). The low reptile extinction
rate is somewhat surprising, given that we lost more than 40% of our bird species and 33%
of our bat species (one of the 3 species has been lost).
A back-of-the-envelope exercise suggests that Maungatautari might once have had a total of
about 20 reptile and amphibian species. In terms of total vertebrate species (not including
fish) on the mountain, we perhaps had about 50 bird species and 3 bat species – so the
herpetofauna was indeed an important component. We currently know of 4 gecko species
(including our very unexpected and surprising Duvaucel’s gecko discovery), one skink
species, tuatara (reintroduced), and one frog species (our surprising Hochstetter’s frog
discovery) existing on the mountain. There is very good reason to believe that more species
still remain as-yet undiscovered (herpetofauna tend to be cryptic by nature) – and looking at
the back of my envelope, it’s possible that another 3 gecko species and another 4 skink
species might yet turn up, and we might yet discover Archey’s frogs on the mountain. We
can also reintroduce at least another 3 skink species which are currently mostly restricted to
offshore islands, and perhaps another one or 2 frog species. So we can potentially almost
completely reconstruct the herpetofaunal community that once occurred on
Maungatautari, which is an exciting prospect. Possibly up to 18 species, which will be the
greatest assemblage of reptiles and frogs at one site in this country!
At best we can restore the avifauna to perhaps 60% of its former diversity (itself a
remarkable achievement), but we might be able to restore the herpetofauna to more than
90% of what it once was. To achieve that full potential, it might be necessary to eradicate
mice from the whole mountain – but pest management techniques have been improving
steadily throughout my working life, and the next step might well be the development of
mouse eradication technology for large rugged mainland sites. Some areas might also need
to be maintained as open habitat for e.g. takahe, tuatara breeding – and for some lizard
species. Other species like red crowned kakariki and snipe might also utilise such habitat,
providing multiple benefits from such management. It is quite conceivable that moa once
maintained such open areas by browsing pressure and trampling, thereby enabling those
other species to flourish in those areas. In the same vein, our planned re-establishment of
petrel breeding colonies (2 species) on the mountain might also enhance the habitat for
reintroduced reptiles like robust skinks and tuatara, and other species. A friend of mine
once attempted to draw a diagram of all the ecological interactions between all the animal
species on one small Hauraki Gulf island with a relatively simple ecosystem. The result was
unbelievably complicated, even though no doubt incomplete. Maungatautari will be much
more complex than that island, and progressively more so as we reintroduce more species.
In pest-free environments reptiles can achieve high densities, and a night walk on
Maungatautari will then be quite something. NZ reptiles and frogs have many unique
ecological, physiological and evolutionary features, which make them of considerable
interest world-wide – and an almost-completely restored mainland community on this scale
will provide an exceptional visitor experience, as well as unique research opportunities.