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Archives For spiders
Warren Chinn, our invertebrate ecologist in Canterbury Conservancy, was lucky enough to be invited on a trip to the Kermadec Islands last month. The 20-day expedition, led by Dr Tom Trnski, marine curator at Auckland Museum, aimed to explore the remote islands for new species. Warren filed this report on his return…
…We tend to form mental pictures of new places based on prior knowledge, other people’s comments, pictures, maps and to a large extent, imagination of ‘how it should be’.
My mental image of the Kermadecs was a scene of romantically isolated semi-tropical lost worlds, the stuff of Joseph Banks and La Peruse. Sea sickness immediately erased such nonsense within hours of leaving Tauranga.
Our first sighting of the Kermadec group was L’Esperance Rock, a mutilated knuckle of basalt erupting from the heaving ocean. It was better than my imagination – a good start.
We steamed past as it was too rough to land and over the following days three more islands in the chain slowly came into view, these were; Cheeseman, Curtis and Macauley.
Each island seemed to me like a massive billboard in the ocean, with an explicit natural history message: “HOW DID THIS HAPPEN?” Followed by two smaller messages: “when did this happen?”, and “what lives here and from where?”
We anchored near Raoul Island, where I landed on the Meyer Island group with (the very erstwhile) Peter de Lange.
The Meyer islands are steep-sided, clad in a dry, friable soil that is shot through with Petrel burrows. An equal number of birds fill the sky, forming a constant blizzard of flapping and diving.
Here was another ecological message: This is what mainland coastal New Zealand would have been like prior to our arrival and the introduction of mammalian predators. These Islands are a nature reserve of the highest value and this is clearly why – they are well-insulated.
The insect fauna on the small islands comprised big headed ants, flies, crickets, leaf hoppers and small moths. Spiders were common and small in size, which probably reflects their arrival on the islands by ballooning, that is, travelling through the air on filaments of silk. Centipedes and millipedes were also present, along with mites and silverfish.
The next week I spent four days on Raoul Island, a proper volcano with a crater lake. After a lovely evening with the DOC staff and volunteers, I tramped over to Denham Bay to collect invertebrates there. Here I set up a malaise trap and collected numerous moths, flies and even spiders.
The most interesting find was a large wolf spider, Geolycosa tongatabuensis, a species that occurs from Tonga to Northland. These spiders represent the invertebrate situation on the Kermadecs, the fauna is composed of a mixture of pacific island and northern New Zealand elements, which makes sense biogeographically.
It is clear that cyclones, drift wood, ocean currents and air systems all carry invertebrates within and between land masses in this part of the globe.
We left Raoul Island and anchored at Macauley Island. Here Peter and I spent two nights. The foot travel was difficult as moving through the chest-high Kermadec fern and Cyperus grass was like step-plugging in deep snow.
However, I collected more crickets, moths, beetles and spiders. I even saw a yellow admiral butterfly but was unable to catch it. Butterflies no doubt get blown to these islands frequently so there will always be some present.
We then steamed to Cheeseman and Curtis Islands. These two are active hotspots on the earth’s surface and this was obvious by the smoke coming from Curtis Island.
We landed on Cheeseman; a strange, almost lunar landscape. The most exciting find was Senecio kermadecensis – a plant endemic to the island – which had Peter very excited. I collected spiders, flies, beetles and crickets.
Our last landing was L’Esperance Rock which was a little hair-raising. A steep pile of volcanic rubble best describes this Island.
However I found two species of pseudoscorpion, numerous crickets and another wolf spider species on the rock. The pseudoscorpions probably got onto the rock via birds, as they are flightless and wouldn’t survive on flotsam. L’Esperance Rock was the very last place I expected to find pseudoscorpions, so there it is; reality was more creative than my imagination.
You can find out more by visiting the expedition pages on the Auckland Museum website.