As New Zealand’s largest native spider and one of only two legally protected spiders (the other being the Katipo), Spelungula cavernicola is pretty special. Their stronghold is in Kahurangi National Park on the West Coast between the Heaphy River and the Oparara Basin with the only other population found near Pohara in the Takaka Valley.
I’ve been to see the spiders on the West Coast from their stronghold in Oparara to the northern limit on the Heaphy River, but I’d only ever heard a rumour about them living in a small cave in the Takaka Valley.
Although they used to be known from a few different caves between Motupipi and Pohara they seem to be now restricted to one small block of limestone (fortunately on public land). Because the cave is so close to a road and easy to navigate it’s been vandalised a lot in the past (we found graffiti back to 1921). Due to this vandalism and the super rare spiders living in it a locked gate was installed in the 90’s.
I have a theory that before humans (maori) arrived with rats, the spiders lived in the damp bush as well as in caves (like several other species of spiders still do). As the predation from rats increased the spiders distribution must have retracted to cave systems and now to the few caves they’re found in today.
When you combine the predation with the destruction of native forests around the caves in the Takaka Valley you have a species under attack with a restricted food supply. Which brings me to one of the things that makes the spiders so unique – feeding! These spiders are expert cave weta killers, dropping down on a thread to ambush the unsuspecting weta before heading back up to the safety of the roof to feed.
It’s hard to say if the Spelungula left in Takaka Valley will still be around in 100 years, on our trip we struggled to find many spiders and there was a significant amount of rat sign in and around the cave. Although DOC does a lot of good work, the spiders don’t seem to be much of a priority at the moment.
On the bright side a local caver has decided to make it her project to trap for rats in and around the cave, and I’ve decided I’m going to spend some time looking around for signs of Spelungula in likely limestone areas. With a bit of attention and effort from locals, cavers and DOC I think its possible for Takaka Valley to be a safe haven for our giant cave spiders.
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