Saturday, November 26, 2011

New Zealand: Blue Duck Country

On my first trip to New Zealand in 1974, I spent a whole day in Urewera National Park, in the North Island, in the company of scientists from the NZ Wildlife Service as they tried, in vain, to show me one of the most unusual waterfowl in the world. The Blue Duck or Whio (Hymenolaimus malacorhynchus) has remained high on my ornithological wish list ever since, though I did see captive birds at the Mount Bruce Sanctuary.

In order to do something about this, on March 6 Kerry-Jayne took us on an all-day excursion to the wild and beautiful northwest corner of the South Island.  Our destination was the Oparara River, near the town of Karamea in the southwestern corner of Kahurangi National Park - New Zealand's second-largest, and surely one of its wildest.

Most of the hikers along the Oparara trail are drawn by impressive natural arches worn through the limestone by the river's passage.  Some of them - not this one, I believe - have been named after imaginary places in The Lord of the Rings (which was of course filmed in New Zealand).

At Oparara we wandered beneath the shade of mighty trees through an almost overwhelmingly rich temperate rainforest.

The forest is dominated by trees like the magnificent rimu (Dacrydium cupressinum), an endemic conifer once heavily logged for furniture and housing.  It is easily identified, and rendered all the more striking, by its long, pendulous branches.

The last time I saw a celery-top pine (Phyllocladus) was on Mount Kinabalu in Borneo. Mountain toatoa (Phyllocladus alpinus) is one of the New Zealand species, fascinating trees that have replaced their leaves with flattened leaflike stems.  Despite its name it occurs at sea level here.

The chief deciduous tree in the forest is the silver beech (Nothofagus menziesii).  The Antarctic beeches are fascinating to a zoogeographer - I have walked through Nothofagus forests in southern Chile that would not be out of place in New Zealand.

This is a Dracophyllum (see previous post) - probably Mountain Neinei (Dracophyllum traversii), a North Island species that ranges from only to the northwest of the South Island.

Like other West Coast forests, the forest at Oparara is rich in ferns, from lacy tree ferns (this one may be Katote (Cyathea smithii), based on its flattish crown and skirt of hanging dead fronds)... delicate epiphytes (this may be Drooping Spleenwort (Asplenium flaccidum))...

...and a host of others in between.  This appears to be crown fern (Blechnum discolor).

Kiokio (Blechnum novaezelandiae) - assuming that is what this is! - is a common fern throughout New Zealand.

This vertical garden of epiphytic ferns includes, I believe, drooping spleenwort and kowaowao (Microsorum pustulatum).

There are a number of ferns in New Zealand with strap-shaped leaves, like this one; it may be Lance Fern (Anarthropteris lanceolata).

We found more Tmesipteris, the peculiar plant I was so excited to see the day before, in the forest; this is, I assume, Tmesipteris tannensis, called Fork Fern in New Zealand.

The words "moss" and "spectacular" are rarely associated in the same sentence, but I can make a minor exception for Hypopterygium filiculaeforme (if that is indeed what this species is; there are some similar ones in the genus), one of the umbrella mosses. 

Dawsonia superba is the largest moss in the world.  I have also seen dense stands of it on Mount Kinabalu in Malaysia.

There are a number of species of liverworts, in New Zealand, but it would take an expert (and I am not even close to being one) to tell which ones these are.

The elephantine object in the background of this photo is a bracket fungus, but the really interesting plant is the spindly object in the foreground.  It is the young shoot of a lancewood (Pseudopanax spp.), and it has been suggested that its stiff, tough leaves - quite unlike the more luxuriant foliage of older plants - evolved to protect them from being browsed by moas.  If this is true (and finding the evidence for such a claim is difficult at best), then this plant is, in Jared Diamond's evocative phrase, an evolutionary "ghost", retaining adaptations that evolved in the presence of animals now extinct.  It is a reminder, perhaps, of the days, not so very long ago, when feathered giants roamed these forests.

I thought of moas again when we met our first New Zealand Robin (Petroica australis).  Not that these delightful little creatures are in any way like moas (except for being birds), but their remarkable tameness - something I remembered from my first encounter with one as it pecked at my bootlaces back in 1974 - got me thinking even more about evolutionary ghosts.

I knew that the robins were tame and inquisitive, but Kerry-Jayne surprised me by demonstrating that rustling your hand in the leaf litter will bring them almost to your fingertips.  It seems that they are adapted to respond to the sounds a large animal - and as this is New Zealand, that probably means a large flightless bird - might make as it crosses the forest floor and, presumably, stirs up insects and other creatures in the litter.  Could robin tameness be a vestige of the days when they had moas, and other flightless giants, to follow around?  Are we moa substitutes in their eyes?

Whatever the explanation for their obvious curiosity about people, robins certainly brighten the forest depths (and are an ideal bird to appeal to a non-birder like Eileen - no squinting through binoculars required!).

One of the worst things European settlers did to New Zealand's endemic birds was to introduce the stoat (Mustela erminia), the animal we call short-tailed weasel in North America.  Controlling this voracious little predator is a neverending necessity if any of the small forest birds are to survive on the main islands, and we came across several stoat traps deployed along the tracks at Oparara.  In some areas stoats are controlled with poisoned bait, but this practice - arguably a practical necessity in remote and difficult areas where the bait can be air-dropped - has met with a lot of local opposition, particularly from dog-owners fearful for the safety of their pets.

Not all of the wildlife along the Oparara lives in the forest.  The valley contains a series of caves, some of which are off limits without a special permit.  Kerry-Jayne and I dipped into one of the more accessible ones in search of two of the specialized creatures that live there: a spider and a cricket.

The spider is the Nelson cave spider (Spelungula cavernicola), one of the largest spiders in the country (though no match for the larger tarantulas).  It is entirely confined to caves in the northern part of the South Island, where it spends its time clinging to the cave roof, waiting to drop on its prey.  In the lower picture you can see the silken guy line that keeps it attached to the surface as it falls.

The cave spider's egg cases hang from the ceiling too, suspended on a silken line.

The other notable cave dweller is an impressively large and long-legged cricket, a Cave weta (one of many species in the Family Rhaphidophoridae).  It has the dubious distinction of being the chief prey of the cave spiders that cling to the roof over its head.

At various points during the day we crossed back and forth over the Oparara river, scanning the waters for a sign of the prime search object of our day, the  Blue Duck, but not a whisper of the bird did we see until our very last sally in the late afternoon. By then I was pretty convinced that the elusive creatures would remain elusive - until a pair sailed down the river into beautiful close view, calling their distinctive onomatopoeic whistle (by the way, the Maori name "Whio", an imitation of its call, is pronounced "fee-o").

The Blue Duck is like no other waterfowl on earth. It is not the only duck in the world to be adapted to rushing streams and a diet of stream-dwelling fly larvae - the Torrent Duck (Merganetta australis) of Sourh America, Salvadori's Duck (Salvadorina waigiuensis) of New Guinea and, to a lesser extent, the Harlequin Duck ( Histrionicus histrionicus) of North America are other examples, but the flesh-pink rubbery beak of the Blue Duck, so beautifully adapted for probing under rocks in the streambed, is the most extreme anatid adaptation in that direction.

After the ducks gave us the requisite mouthwatering views, they proceeded to give an equally impressive demonstration of why they are so hard to see. One by one they crossed to the bank, hopped onto the shore and simply disappeared beneath the vegetation.

Dusk began to fall not long after the Blue Ducks made their appearance.  We ended our day in a nearby campground, where we received a troupe of visitors: a family of Wekas (Gallirallus australis), an adult and two half-grown chicks, barreling down the trail in our direction in a fast waddling run, obviously in search of whatever bounty we might provide them.  Ah, New Zealand... where the flightless rails hunt down the birders...

The adult (the female, I presume) stashed her offspring in the shelter of a patch of ferns before setting off to give us (and a camper settling in for the night) her undivided attention.

Trouser legs and camping gear got a thorough inspection, successfully in that we finally broke down and gave her some bits of bread.  At last we left her and headed off into the night while our visitor, presumably, dealt with the remaining camper.

Friday, November 4, 2011

New Zealand: Fascinating Fernery

On the way back from Punakaiki (see previous post), Kerry-Jayne stopped at the Pororari River Track (in Paparoa National Park) to show me a unique, if unspectacular, plant. The Pororari winds through a spectacular forested gorge on New Zealand's west coast, emptying into the sea at Punakaiki itself. The lush and humid forest along the track is particularly rich in ferns, and it was a fern - of sorts - that we had come to see.

New Zealand is particularly rich in ferns and the plants usually called "fern allies", though how closely related some of them actually are to ferns is open to question.

Many of Pororari's ferns grow epiphytically - that is, on the trunks and limbs of trees. This one appears to be Microsorum scandens, a fern that features strap-like, undivided juvenile fronds and deeply-lobed adult fronds in the same clump. The species is well-named: scandens means "climbing".

Here is the plant we were looking for - not much to look at, but I was very excited to see it. It is Tmesipteris elongata, and when I studied botany as an undergraduate it was regarded as one of the most primitive plants in the world. Tmesipteris, the fork fern, and it's only relative, Psilotum, the whisk fern - the so-called whisk fern - were thought to be living representatives of the very first green plants to invade the land. Like these early plants, Tmesipteris and Psilotum have neither roots nor leaves (the little structures that look like leaves on Tmesipteris, put simply, aren't. They lack vascular tissue, the vessels that provide both support and transport in higher plants). What is more, they carry their packets of spores (sporangia, the little green blobs that look vaguely like miniature olives) out in the open, as the earliest plants did (though not, as it happens, in the same way).

Unfortunately for this lovely idea, it appears that Tmesipteris and Psilotum are simply ferns that have somehow lost their more advanced features. Modern molecular studies place them close to the adder's tongue ferns (Ophioglossaceae). Oh well... I was still excited to find this little fellow, growing unobtrusively among less celebrated plants.

Here is an epiphytic plant that is neither a fern nor a fern ally, but a liverwort - don't ask me which one! Liverworts are not vascular plants, but are closer to mosses.

This is unquestionably a fern, and to my eye it is one of the most unusual and striking of them all. I first saw kidney fern (Trichomanes reniforme) in 1974, on Little Barrier Island. I was struck by it then, and was delighted to see it again so many years later.

The kidney fern belongs to the filmy fern family (Hymenophyllaceae). It doesn't look too much like other filmy ferns, but it share with them extremely thin fronds, only a few cell layers thick, that dry out very easily. Kidney ferns can survive drying, shriveling and then reopening when the rains come, but their presence is a sign that the forests where they grow are, at least some of the time, humid places indeed. The little blobs around the rim of this fertile frond are the spore-bearing bodies, or sori.

Here are some more traditional ferns.I'm not sure what the upper plant is, but the lower one appears to be crown fern or petipeti (Blechnum discolor).

I believe this to be one of the many New Zealand species of Coprosma - possibly karamu (C. robusta), but there are some fifty to choose from.  We have Captain Cook's botanists to thank for the unlovely generic name, from the Latin copros, meaning dung.  Apparently the specimens they collected stank up their shipboard cabins.

This is a Dracophyllum,one of the plants that gives New Zealand forests - at least to a northerner's eye - a distinctly exotic appearance.  Though it doesn't look it, it is a relative of heathers and heaths (Ericaceae), as one of the plants formerly included in a separate, largely southern-hemisphere family, Epacridaceae.

In most parts of the world, if you found one tree busily engaged in trying to choke the life out of another, you would be safe in assuming that the murderer in question was a strangler fig. In New Zealand, though, it is more likely to be a northern rata (Metrosideros robusta), a member of the myrtle family (Myrtaceae). While other ratas (and other Metrosideros spp., like the famous ohia lehua (M. polymorpha) of Hawaii) usually grow from the ground up like respectable trees, the northern rata starts life as an epiphyte high in the canopy. In time, like a strangler fig, its roots reach to the ground, forming a robust pseudotrunk that envelops and, eventually, smothers its host (though there is some argument as to whether the rata actually contributes to the death of the host tree).

The result can be a truly impressive tree, reaching 25 m in height. This one, it seems is well on its way.