The Protection of New Zealand's Herpetofauna
The conservation of New Zealand’s herpetofauna is a fairly new subject, in terms of New Zealand’s long conservation history. Unlike many of our native birds which were absolutely protected by 1906, New Zealand’s Herpetofauna was largely overlooked, with a couple of exceptions (Tuatara in 1907, and our native frogs in 1922).
The major movement for herpetological protection began during the 1960s and 1970s when more attention was given to this poorly known group of New Zealand fauna. In 1981 the Wildlife Act 1953 was extended to grant full legal protection
to all native lizards except for a few of the more common species (forest geckos, common geckos, common skinks and copper skinks). By 1997 full legal protection was extended to also include these common species. Under section 3 of the Act, all New Zealand lizards (geckos and skinks) are 'absolutely protected wildlife', this means they
cannot be collected from the wild, handled, disturbed, or held in captivity without a permit from the Department of Conservation.
Threats to New Zealand’s Herpetofauna.
New Zealands herpetofauna face many threats, from a range of anthropogenic sources. Foremost among these are the threats from invasive species (primarily introduced mammals) and habitat destruction, but also the potential threat of disease and the ongoing impacts of climate change.
Invasive species
Luckily, although not officially protected until much later than many of our bird species, our native herpetofauna did in fact benefit from some of the conservation methods that were employed for protecting these other species. Foremost amongst these was the control of the introduced mammalian pest species and the protection of native habitats throughout the country.
As is the case with all of our native land animals, reptiles are extremely susceptible to predation by the entire suite of mammalian predators that now call New Zealand home, and thus many reptile and amphibian populations, especially of the larger-bodied species, have become extremely restricted in their distribution.
The arrival of kiore / Polynesian rat (Rattus exulans) with early maori settlers, and the later arrival of ship rats (R. rattus), norway rats (R. norvegicus), mice (Mus musculus), mustelids (Mustela spp.), hedgehogs (Erinaceus europaeus) and cats (Felis catus) inevitably led to the localised extinction of many larger bodied lizards. Species which are large, nocturnal and terrestrial, such as robust skinks (Oligosoma alani) and McGregor's skinks (Oligosoma macgregori), were particularly vulnerable and now only survive on pest-free islands. Many other species are either endangered on the mainland or in a gradual decline due to the impacts of these invasive predatory mammals.
The arrival of rainbow / plague skinks (Lampropholis delicata) to Auckland in the 1960's, and their subsequent spread around much of the North Island, brought with them the concern that they may outcompete some of our smaller native species such as Copper skinks (Oligosoma aeneum). Plague skinks, having evolved in a country (Australia) where predatory mammals are present, are better adapted to survive the impacts of New Zealand's introduced mammalian predators. Coupled with the fact that they breed at a much-faster rate than any of our native skinks, the potential for them to have an impact is significant. However, no solid evidence has so far been presented to demonstrate that they are having an impact on our native species. Control of plague skinks by the general public is also discouraged because of the difficulty in distinguishing them from our native species which often live in the same habitat.
Habitat destruction
The ongoing impacts of habitat destruction for anthropocentric activities including agriculture, mining, housing and other development is also having an impact on our native species. Many of our lizards prefer to live in habitat which has historically been regarded as wasteland (e.g. Manuka/Kanuka scrub, Matagouri/Coprosma spp. shrubland and thick rank grass such as Kikuyu), and much of this has been cleared with little regard to the protected lizard species that might have been present.
Thankfully, our native species are afforded some protection under the Wildlife Act 1953 and Resource Management Act 1991, although many species are still in decline due to the ongoing expansion of human civilisation.
Disease
The ever-present threat of disease has been observed on the global scale in recent times, with the impacts of the chytrid fungus (Batrachochytrium dendrobatidis) causing the extinction of many species of amphibian worldwide. An 88% decline in Archey's frogs (Leiopelma archeyi) on the Coromandel Peninsula during the late 1990's and early 2000's has been attributed to this same pathogen.
Having evolved isolated from the rest of the world for millions of years, New Zealand's herpetofauna may be particularly susceptible to exotic pathogens which are found in other species overseas. With an increasingly connected world, biosecurity is more important now than ever, and there is a need to remain vigilant about the potential introduction (deliberate or accidental) of exotic herpetofauna and their pathogens into New Zealand.
Climate change
It is currently uncertain what impacts climate change might have on our herpetofauna.
Some species such as Tuatara (Sphenodon punctatus), which have temperature based sex-determination may start to see sex ratios skewed towards males as the climate warms, which is a threat to populations in the long-term. Alpine species such as black-eyed geckos (Mokopirirakau kahutarae) may have their ranges contracted (and others have their range shifted), as the climate warms, and the higher temperatures will likely promote higher numbers and diversity of pest mammals in alpine lizard habitat - where they are currently being suppressed by snow / low temperatures over winter.
For other species with small ranges, the increasing volatility of weather patterns under climate change may prove critical. Many of our lizards live in small, fragmented habitats which may be at risk of severe storm events. Species such as cobble skinks (Oligosoma aff. infrapunctatum "Cobble") and Kapitia skinks (Oligosoma salmo) have already suffered declines due to severe weather events, the former species now only existing in captivity due to their entire habitat being wiped out during a cyclone in 2017. Many other species (and populations) exist in similar fragile habitats, and will face increasing threats as severe weather events become more common.
What is being done?
Thankfully there are many ways in which people can help New Zealand's herpetofauna. Many of our species respond well to predator control and there are many community based restoration / conservation intiatives which benefit herpetofauna directly or indirectly.
Some of our rarer species have seen targeted conservation action which has included creating predator free sanctuaries, breed-for-release programmes, and translocations to predator free (or predator controlled) areas.
To learn more about conservation of NZ herpetofauna, check out the following links:
- Conservation status of NZ's Herpetofauna
- What is being done to protect our Herpetofauna?
- Robust Skink Breeding Programme
- What can you do?
References:
Daugherty, C. H., Patterson, G. B., & Hitchmough, R. A. (1994). Taxonomic and conservation review of the New Zealand herpetofauna. New Zealand journal of zoology, 21(4), 317-323.
Miskelly, C. M. (2014). Legal protection of New Zealand’s indigenous terrestrial fauna–an historical review. Tuhinga, 25, 25-101.