Friday, March 23, 2012

New Zealand: Miranda

Our circuit of the Coromandel Peninsula (see previous entry) brought us, on March 25, 2011, to the estuary of the Thames, where Eileen and I paid a visit to a famous birding mecca, the Miranda Shorebird Centre.  Here I hoped to catch up with another rare New Zealand endemic, in its way one of the most peculiar birds in the world.

To see it, we set out across the boggy flats of the estuary, in my case clutching a spotting scope conveniently rented from the centre headquarters.

Our target was a rather battered hide overlooking the estuary waters, already crammed with visiting birders.

Across the water, literally thousands of shorebirds (or waders, if you're not from North America) crowded together, waiting for the lowering of the tide, repeatedly bursting into wheeling flight.  Many of them were migrants from the north: Bar-tailed Godwits (Limosa lapponica), Red Knots (Calidris canutus) and others.

Among them, though, were the birds I sought: Wrybill Plovers (Anarhynchus frontalis), the only bird in the world with a bill that twists sideways.  It, too, is a migrant at Miranda, not from the north but from breeding grounds on braided streams in the South Island (where its peculiar bill is useful for retrieving small invertebrates from beneath rounded river stones).

There are only about 5300 Wrybills left, and up to 40% of them winter at Miranda.  Unlike the New Zealand Dotterels I saw at Opoutere, they never came close (a pity, as I would have loved to get a good look at that weird bill).  As a consolation, their aerial evolutions were both beautiful and spectacular.  It's not often you can see roughly one third of a bird's global population in a single binocular field!

Photographs, of course, miss out on the sheer noise and excitement of the Miranda experience.  Here is bit of video to compensate.

We lingered for quite a while with the Wrybills, but finally made our way back across the flats, past small chattering groups of Pied Stilts (Himantopus leucocephalus).

Here we saw both of New Zealand's larger resident herons.  This is a White-faced Heron (Ardea novaehollandiae).

The Eastern Great Egret (Ardea modesta), an abundant bird elsewhere, is a prized rarity in New Zealand (where it is know as the Kōtuku or White Heron), where it breeds only in the Okarito Lagoon on the South Island.

The egret brought us to the end of our natural history experiences on this trip to New Zealand.  From here we headed back to Auckland to visit friends before heading off to Australia, our next destination.  Was the trip a success? Eileen's expression, I think, makes the answer abundantly clear!

New Zealand: Coromandel Plovers

From Rotorua we drove north (on March 24, 2011) to the Coromandel Peninsula. The Coromandel is a lovely place, just a bit off the tourist track, and worth anyone's time.  I, though, had a specific target in mind: a rare shorebird for which the Coromandel is the last, best refuge.

The Wharekawa Harbour Sandspit Wildlife Refuge near Opoutere protects an important nesting ground for the New Zealand Dotterel (Charadrius obscurus), a species now reduced to some 1700 individuals.

New Zealand Dotterels nest on open sand beaches, and like birds of similar nesting habit elsewhere they are threatened by the fact that we humans are also attracted to such places - not to mention the risk of predator by exotic mammals that almost every New Zealand endemic faces.  On the Wharekawa sand spit the birds are protected by a fine-mesh fence designed to keep out stoats, hedgehogs, cats and (one hopes) people.

The result, I was delighted to find, was that the dotterels appear to be thriving there, and once I walked down to the beach (on the permitted side of the fence, of course!) this one at least seemed not in the least put out by my presence.

This species was once considered to be a southern-hemisphere representative of the golden-plovers (genus Pluvialis), but it is now simply regarded as a large, large-billed typical sandplover (Charadrius); and, to my eye, it certainly looks like one.

The birds on the beach were quite variable in plumage; this color-ringed individual looks quite unlike the bird in the earlier pictures.

Still another individual, with differently-coloured rings, is more uniform above and whiter below than the others, and a bit shorter-billed.

A Variable Oystercatcher (Haematopus unicolor) shares the beach with the plovers.

From Opoutere we drove north, rounding the top of the peninsula to the town of Coromandel where we spent the night.  The next day we continued our circumnavigation, down the rugged western side, with views across the Firth of Thames.

Rugged, sprawling Pōhutukawa trees (Metrosideros excelsa) marked the headlands....

...while Spotted Shags (Stictocarbo punctatus), including strikingly-marked adults, sat on the rocks below - beautiful birds in a lovely landscape.

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.