Monday, 20 January 2014 lose some

I went to Kaituna Valley a couple of days back to look for Cantuaria borealis and the ubiquitous C. dendyi. I am focussing on C. dendyi for some of my ecology studies, mainly because there are many populations around Canterbury, but also because it is the type species (the species to which the genus name is permanently linked - so if for example C. borealis was found to be more related to Australian trapdoor spiders, such that it was found to be a different genus from C. dendyi, C. dendyi would remain Cantuaria and C. borealis would be given a different genus name). Cantuaria dendyi's burrows are lidded, but C. borealis does not make lids.

The description in C. borealis just said "Kaituna valley", so I drove right into the valley and parked by the gate to a forest track. Native NZ moist forest is very exciting to me - it's full of plant species that seem so weird and exotic, such as ferns, mosses, lichens and lianas. There are also introduced species, but they hardly affect the spooky, wild forest feeling. Walking up the track, I kept an eye out for neat circles and open webby burrows. There were many tiger beetle and possibly bee burrows, and some small silk-lined burrows that I reckoned were likely to belong to tube-dwelling spiders (Segestriidae, not Idiopidae). The tubes were messy and the silk was slapped on thickly.

I found some Amanita toadstools (aka fly agaric) and stopped to look. Different stages of maturity were there, with smaller fruiting bodies pushing through the pine needles:

while the older toadstools took on a variety of different shapes:

The white bits on the top are the remains of a thin skin (the universal veil) that encloses the fruiting body of a fungus when it is small.

One particularly brightly coloured toadstool had a wide, silk-lined burrow underneath it. Toadstool and burrow were in the middle of the path, embedded in pine needles. This burrow could be Cantuaria.

I marked the burrow and moved up further, finding a couple more burrows on the ground. They were very far apart, unlike two Cantuaria populations I had seen so far. I crawled around in the denser forest for a bit and found another burrow. Then I left to go and find some mites on Banks Peninsula, before returning after sunset (about 9pm).

It was pretty chilly and windy, but I had come prepared - weather changes quickly when you're in the middle of the Pacific Ocean. I approached the big burrow under the toadstool, which I was most sure was Cantuaria, and tickled the entrance with some grass. Soon enough, a flicker of furry feet betrayed the lady of the house. I harnessed up Pete the beetle and placed him next to the entrance. Spider feet came closer and closer, nanometre by nanometre, and I could see the claws at the tip of one of her legs in the red glow of my headlight. The beetle twitched and the spider sidled closer. She had responded so quickly to the grass, but the beetle did not seem so enticing. Pete was nearly inside her burrow now, and she made a lunge. I thrust the trowel into the ground, but she was too quick for me and had retreated underground. I had destroyed her burrow, making tempting her out impossible. I expect she wasn't hungry enough. Never mind; I know where she lives.

Frustrated, I went to look for the other burrows. The markers were nowhere to be seen. I searched everywhere, got down on all fours, used a variety of different lighting arrangements and probably walked about a kilometre up and down the hill searching. Unfortunately GPS records are not particularly reliable under forest cover. When I finally left, it was midnight. Four hours of fieldwork and no new specimens. However, it was not a complete waste of time - I learned the following things...

  • I need better markers - perhaps with reflectors.
  • I need marker tape to mark the general location of burrows.
  • This track will probably make a good location for pitfall trapping.
  • I should get permission to be there after dark - they did close the gate and I probably shouldn't have been in there.

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