Wednesday, March 21, 2012

New Zealand: Glow-Worms, Geysers, Mud and Ducks

There can't be many tourist attractions built around gnat larvae.  The Waitomo Glowworm Caves, however, are an exception, and on March 22, 2011, we found ourselves sailing through an underground passage by the light of Arachnocampa luminosa, the titiwai or New Zealand Glowworm.

Arachnocampa glowworms (there are other species in Australia) live on cave roofs, where they lower sticky silken threads, up to 30-40 cm long, and angle with them for flying insects, which they reel in and devour (unless there is no prey available, in which case the larvae eat each other).  

The glow, which apparently lures in their prey (a hungry glowworm glows more brightly than one that has recently dined), is produced by the same chemicals (luciferin and luciferase) that is responsible for the luminescence of fireflies (which, unlike the titiwai, are beetles, not flies).  Unfortunately I was unable, in the dim light, to get a photo of the larvae themselves, so a few views of the cave will have to do.

Speaking of tourist attractions, the tourism centre of the North Island is the area around Rotorua, famous as a literal hotbed of geological turmoil.  Not content with geysers and pools of boiling mud, however, tourism developers have added everything from Maori culture centers to the opportunity to roll down a hill in a plastic ball.  Our friends tried that one; Eileen and I pointedly did not.

We did, however, all go to the Maori-operated attraction at Te Puia, a blend of culture and geology.

Eileen and I did our best, of course, to appreciate Maori culture....

However, for the purposes of this blog we'll concentrate on the geology (even if this means simply showing pictures of Eileen and I playing tourist in from of the local geysers).

The geysers, of course - a feature of the Whakarewarewa
geothermal area - are spectacular, every bit as much as the perhaps more famous ones at Yellowstone in the United States.

Almost a spectacular as the geysers themselves are the centuries-old accumulations of minerals around them - technically, spicular and columnar geyserite - stained with sulphur deposits and patches of thermophilic bacteria.

Here you can see bright yellow deposits of sulphur...

...And here, green, amoeba-like mats that I assume represent colonies of bacteria.

For variety, here is a vascular plant growing among the geysers: Mānuka or Kāhikatoa (Leptospermum scoparium), probably best known overseas as the source of a distinctively-flavoured honey for which a long list of health benefits has been claimed, including the ability to kill a wide range of bacteria.  Note the sharp leaf-tips, a feature distinguishing this species from the rather similar Kānuka (Kunzea ericoides).

Bubbling mud can be surprisingly entertaining to watch, especially if you hum a bit of Flanders and Swann's Hippopotamus Song while doing so.

Our friends wanted to visit Lake Rotorua to go paragliding.  I leave it up to the reader to decide which of us (Eileen and I relaxing by the lake, or the two figures lashed together and dangling from a parachute far above) are having more fun.

Instead of soaring (in terror) into the empyrean, I opted for a stroll along the shore.  A little grove yielded a few New Zealand Grey Fantails (Rhipidura fuliginosa), one of the most charming (and most successful, I believe) of the islands' native songbirds.  Their constant tail-switching appears to be a foraging aid, startling insects into revealing themselves so the bird can snap them up.

With a few exceptions like the fantail, songbirds outside the forest are more likely to be British than antipodean.  The Song Thrush (Turdus philomela) is becoming scarce in its native range; it seems easier to find in New Zealand.

Lake Rotorua is popular with ducks.  These are New Zealand Scaup (locally known, confusingly, as "Black Teal") (Aythya novaeseelandiae).

The scaup is a remarkable outlier.  The other scaups are all northern-hemisphere birds (though a related bird, the extremely rare Madagascar Pochard (A. innotata), is also confined to the south).  How one ended up in the far south is a bit of a mystery.  There are only some 5-10,000 of them, making this the world's rarest scaup as well (but you wouldn't know that at Lake Rotorua).  The "head-up" display of the middle bird (these are all males) is something I have often seen Greater and Lesser Scaups (A. marila and A. affinis) do back home on the Toronto waterfront.

Another mystery bird in New Zealand, in a way, is the Black Swan (Cygnus atratus).  This might seem an odd thing to say, as Black Swans are legion in New Zealand - there are certainly lots of them on Lake Rotorua - and have been regarded as a highly undesirable introduced pest.

But is it?  It is certainly true that there were no Black Swans in New Zealand when Europeans first arrived, and that the current population is largely descended from birds introduced in 1864, perhaps supplemented by occasional natural immigrants from Australia.  New Zealand, though, has not always been swan-free.  Subfossil remains show that there were once native swans here, probably hunted to extinction by the first Maori.  These were long regarded as an extinct species, Cygnus sumnerensis.

It appears, though, that sumnerensis is  not a separate species, but a somewhat larger-bodied subspecies of atratus.  In other words, the extinct New Zealand birds were, in fact, Black Swans.  With that, the Black Swan becomes a native New Zealander.  As they are aliens no more, we can enjoy these beautiful birds (as I certainly did) without guilt.

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