Source: NZ Department of Conservation
Date: 18 June 2025
A population of the rare and unusual spider, which lives in the “Crazy Paving Cave” in the Ōparara Valley on the South Island’s West Coast, is increasing and scientists think it is because the spiders have had a break from visitors.
The spiders had been monitored for a number of years, with a steadily declining population, when the decision was made to close the cave to visitors in 2022.
Since then, spider numbers have shown a steady increase from an average of eight found during monitoring in 2022 to 33 in 2025. Rangers have also seen signs of the spiders breeding.
Senior Ranger Scott Freeman says people unknowingly interupt the natural behaviour of the spiders with bright lights, vibration, sound, and the heat they bring into the cave.
“The cave has a low ceiling, and it’s quite small, so people get close to the spiders, which don’t like large creatures such as humans wandering round.”
Scott says, “We have proven in many parts of the country that when we remove or manage the threats, restore habitats or modify how we use or interact with nature, it comes back, and we can see that here with the spiders.”
It is thought that numbers of spiders may have peaked, and scientists are keen to see what happens in the next year before decisions about visitor access to the cave are made.
The spiders are relatively long lived, with baby spiders taking two to three years to mature. Most spiders complete their life cycle in a year.
New Zealand’s native species are unique and special. On average, 70% of our nature is found nowhere else in the world. 93% of New Zealand’s estimated 2000 spider species are only found here.
Nelson cave spiders evolved separately from the rest of the world for millions of years and are thought to be directly descended from the earliest true spiders. They may be the missing link between primitive and modern spiders.
These spiders live near cave entrances and mostly eat cave wētā, which they drop onto while attached to the cave roof by their web. They are also found in Golden Bay and were the first spider species to be protected under the Wildlife Act.
The other walks and experiences in the Ōparara and the adjacent Box Canyon Cave remain open for visitors.
Background information
Crazy Paving Cave gets its name from its floor of ancient, fragile, fine deep sediment which has dried out slowly, cracking and curling into what looks like large, distorted paving stones.
It’s a dry cave where the sediment has stayed in place unchanged for hundreds of years. It’s like a time capsule holding information about what life was present when water once washed into the cave.
Contact
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