The New Zealand Threat Classification Series hits 50

Source: NZ Department of Conservation

A milestone worth celebrating for Aotearoa New Zealand’s biodiversity

The New Zealand Threat Classification Series has officially reached its 50th issue! That’s 50 deep dives into the state of our unique species, 50 scientifically robust contributions to conservation knowledge, and 50 reasons to feel proud of the mahi behind this nationally important series.

Lepidium rekohuense | Credit: CC-Y Peter de Lange

What is the Threat Classification Series?

Since 2013, the New Zealand Threat Classification Series (NZTCS) has served as a cornerstone of conservation science in Aotearoa. It’s a scientific series, but not the gathering dust on a shelf kind. These publications are all open access, living online on DOC’s Science Publications webpages, and widely used by researchers, conservationists, NGOs, and agencies here and overseas.

Each issue shares the most up-to-date conservation status of New Zealand’s wild species, from algae and spiders to birds, fungi, and everything in between. On average, three publications roll out every year, covering 23 different species groups. More than 16,000 species have been assessed to date.

Atrichopsis tenuirostris | Credit: Marley Ford

Flashback to issue #1

The very first issue, published in June 2013, was a whopper, compiling results from 21 peer-reviewed studies covering 12,223 species. It marked a major shift, moving NZTCS data from membership only journals to an open, freely available platform.

The second issue, also released June 2013, helped shape the series’ now-recognisable structure, though the look has evolved over the years (including the addition of the official NZTCS colour scheme in 2021).

We’ve actually come full circle – the series launched with a reptile assessment in 2013 and now issue #50 celebrates reptiles again.

Enjoy the photos in this blog. They’ve all featured on the cover of a report.

Awakopaka skink/Oligosoma awakopaka gravid female Homer Fiordland | Credit: James Reardon

It started with spreadsheets

In the early days, each issue came with an accompanying Excel spreadsheet packed with data. In 2018, this transformed with the creation of the NZTCS database, and supportive data is now accessed directly through digital links inside each publication.

A global audience

The NZTCS isn’t just for New Zealand audiences. In 2025, it had more than 2,500 reads, including readers in 68 countries. Outside Aotearoa, the biggest readership comes from the United States, Australia and China.

The most popular publication so far?

Issue 36 – Conservation Status of Birds in Aotearoa New Zealand, 2021. The issue was a real milestone, announcing that North Island Brown Kiwi, while remaining conservation dependent, was no longer threatened or at risk of becoming threatened thanks to 30 years of community conservation.

A massive collaborative effort

Behind each issue lies a considerable cross-sector effort. More than 200 authors – from DOC, Crown Research Institutes, universities, museums, and consultancies – have contributed their expertise.

Why the NZTCS matters

The NZTCS provides evidence-based assessments of extinction risk for species across Aotearoa, including marine species. It complements the IUCN Red List of Threatened Species, but tailors its criteria to New Zealand’s unique natural environment such as island ecosystems, naturally small populations, and species with restricted ranges found nowhere else in the world.

Sperm whale in Kaikoura | Credit: Will Rayment/NZ Whale Dolphin Trust

Panels of experts reassess each species group roughly every five years, weighing abundance, distribution, and population trends. The result is a clear, nationally relevant picture of how our species are doing and where conservation energy is most needed.

Here’s to 50 issues, and many more to come

The NZTCS is more than a set of publications. It’s a living record of the state of Aotearoa’s biodiversity. It informs policy, recovery planning, advocacy, science and even national reporting.

Reaching 50 issues is a huge achievement. And as long as our taonga species need champions, the series will keep growing, evolving, and supporting the mahi to protect our natural heritage.

Aphis coprosmae

Aphis coprosmae | Credit: Bioeconomy Science Institute

Ngā mihi nui to everyone who has contributed, supported, read, shared, or relied on this work. Here’s to the next 50!

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