Conservation Lessons from New Zealand’s Imperiled Herpetofauna

Tuatara (Sphenodon punctatus) – Houston Chandler

            New Zealand is composed of a collection of islands located in the southern Pacific Ocean. The land mass that eventually formed these islands broke away from other land masses between 80 and 65 million years ago. Today, New Zealand is located approximately 2,000 km from Australia and 1,000 km from the closest Pacific islands. This long history of isolation has fostered the evolution of a flora and fauna that is unlike anything else in the world. New Zealand’s native species include more than 110 species of lizards (geckos and skinks), 4 species of frogs, and 1 species of the lizard-like tuatara. All of these native herpetofauna species are endemic to New Zealand and many have relatively small ranges or are restricted to particular ecosystems. Furthermore, recent taxonomic work has split many of the native lizards into multiple species, and species descriptions are likely to continue as more species are evaluated using modern genetic techniques. Unfortunately, as we will see in the rest of this article, New Zealand’s native herpetofauna (and other taxa) are currently facing severe conservation challenges that have already led to population declines and even extinctions.

Northern Spotted Skink (Oligosoma kokowai) – Houston Chandler

            I recently traveled to New Zealand to attend the 9th World Congress of Herpetology. The meeting was hosted during early January 2020 in Dunedin, which is located at the south end of the southern island. The World Congress is a truly international meeting, bringing together herpetologists from around the world to share their research, discuss current trends in herpetology, and learn about the latest work in herpetological conservation. Sharing research at a meeting like this is a great way to introduce your research, study species, and conservation work to an audience that may not be familiar with them. For example, I gave a presentation documenting the history of Eastern Indigo Snake conservation, and The Orianne Society’s role in protecting this species. Because the meeting was hosted in New Zealand, there were lots of presentations about New Zealand’s native herpetofauna and the conservation challenges that these species face. In addition to attending the meeting, I spent the holiday season traveling across the country from North to South, which gave me the opportunity to see some of the conservation issues and solutions firsthand.

            To understand the current state of New Zealand’s ecosystems, you must go back to the late 1200s when humans first colonized the landmass. The first people to make it to New Zealand were Polynesians who were traveling south from island to island across the Pacific Ocean. Once established these settlers began to change New Zealand’s ecosystems forever. New Zealand has no native land mammals, creating an environment that freed its native species from common predation pressures found in many other ecosystems around the world. This is most evident by the large number of flightless birds that have very few defenses against predation attempts. Moas were large flightless birds that were driven extinct over a relatively short time period, primarily by overharvesting from Polynesian settlers. Haast’s Eagles (once the world’s largest eagle) that fed on moas soon followed, and New Zealand’s unique fauna was already beginning to erode because of human colonization.

Kiwis are perhaps the most well-known of New Zealand’s many flightless birds. – Houston Chandler

            Europeans from several countries became the dominant human population during the 1800’s, accelerating the degradation of native ecosystems. These settlers brought with them many nonnative species, both intentionally and unintentionally. This included several species of mammals, most notably rats and mice, members of the weasel family, cats, Australian possums, and large domestic herbivores. Many of these nonnative species spread rapidly throughout New Zealand’s ecosystems, finding the completely naïve native species to be easy prey. European colonists also increased the rate of habitat loss through clearing of land for farming and other uses. These two factors combined to decimate many of New Zealand’s ecosystems by the late 1900’s, and it became clear that drastic conservation interventions were needed.

Displays warning of the negative impacts of invasive predators were common. – Houston Chandler

            By the end of the 20th century only about 25% of the original native forest cover remained on New Zealand. This led to increased pressure for the government to ban logging on public lands, which occurred in the early 2000s. Thus, much of the remaining natural forest cover is now protected from future habitat destruction, although the total loss of forest cover since human colonization is quite striking. Like many places around the world, this dramatic reduction in forest cover and conversion of many native ecosystems to other uses is now the reality of conservation in New Zealand.

Deforestation history of New Zealand. – Houston Chandler

            Even with increased protections for native forests, the widespread introduction of alien species to New Zealand’s ecosystems still presented a monumental challenge. Many of the exotic species thrive in artificial and natural environments, making their populations difficult to control and their negative impacts wide-reaching. For example, rats, stoats (weasels), and Australian possums kill approximately 25 million native birds each year, and several species have already been eaten to extinction or near extinction. In an attempt to limit these negative impacts, predator control programs in native forests are widespread. The goal of these programs is to reduce the population size and ultimately eliminate the invasive mammal species through a combination of poison application and trapping. These efforts have already been successful on smaller islands, but success will be more difficult in the larger tracts of public lands on the two main islands. The optimistic goal is to have a predator free New Zealand by 2050 (

Mammal trap – Houston Chandler

            Despite these predator control efforts, it was clear that many of New Zealand’s surviving species would not make it to 2050 unless other conservation efforts were put in place. New Zealand is now one of the world leaders in translocations and captive breeding of rare native species. Because predators represent the main threat to many of the rarest species, establishing populations in areas without predators is an effective way to create insurance populations. These populations are generally established in one of three ways: completely captive (i.e., in a zoo), in a fenced ecosanctuary where predators have been removed and are actively controlled, or on small predator-free offshore islands. Translocations have proven an effective management tool for many of New Zealand’s rarest species, including the Kakapo (a large flightless parrot) and the Tuatara. Tuatara were once widespread across New Zealand, but only exist today on offshore islands and inside fenced ecosanctuaries. These lizard-like reptiles are the only surviving member of an ancient order of reptiles that is a sister taxon to squamates (lizards and snakes). The populations of tuataras and other animals that have been established in places free of invasive predators may one day be used to repopulate mainland New Zealand with some of its rarest species.

The takahe (Porphyrio hochstetteri) is one of the rarest birds in the world and was thought extinct until a population was rediscovered allowing for captive breeding efforts to boost the current number of individuals to several hundred. – Houston Chandler

            Overall, my trip to New Zealand and the World Congress of Herpetology was incredible, and it was a valuable experience to see how other countries approach difficult conservation issues. For some of New Zealand’s endemic wildlife this work unfortunately came too late, but for others conservation efforts will likely be successful, allowing species to return to areas of the mainland where they were once extirpated. These efforts have been powered by the dedicated work of many biologists but also require buy in from a public that can sometimes be skeptical of programs designed to kill mammals, regardless of whether or not it is ecologically beneficial. As other challenges mount for alpine and island wildlife (i.e., climate change is already impacting sex ratios in one island tuatara population), sharing successful conservation approaches across international boundaries is one of the many ways that we can make better decisions for imperiled wildlife.

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