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  Lord Howe Island - a naturalist's observations at North Bay

Posted: October 31, 2007 20:20
North Bay (Mount Eliza in background)
North Bay (Mount Eliza in background)


Written by Andrew Byrne, October 07

We were shown North Bay by Ian Hutton, naturalist and now local resident of Lord Howe Island. The first thing we saw was a lazy (or perhaps sick) turtle about 400mm shell diameter, lying on the sand as we arrived by boat across the lagoon.
Ball's Pyramid
Ball's Pyramid


We walked to a clearing where Mr Hutton used some laminated cards to demonstrate the geologic formation of the island millions of years ago. It seems that like Hawaii in more modern times, a weakness in the earth's crust allowed a series of volcanic eruptions under the sea as the Pacific and Australian tectonic plates moved slowly against each other. There were four of five such eruptions in a line from up near Bougainville, including Middleton and Elizabeth Reefs, Lord Howe Island and Balls Pyramid to the south. The same crust weakness has now migrated to a point 400km south of Lord Howe and shows little if any current volcanic under-sea activity. We were told that a similar, parallel line of undersea mountains exist between this chain and the Australian east coast, known mainly to fishermen who are aware that the nutrients pushed up by the currents attend a much better range and quantity of fish than in the open fallow Pacific ocean.
The Old Gulch at low tide
The Old Gulch at low tide


We were shown an undersea map of the island which was remarkable in that nearly all of the raised 'land' was submerged at current sea levels with only 2-3% exposed at the island we know today. Likewise, there was a large sea channel between the island and Balls Pyramid, showing that the two were separate islands caused by different volcanic eruptions.
To demonstrate the nature of the formation of the island, we were taken to the 'Old Gulch' which is a rocky inlet about 300 metres across a sandy isthmus from North Bay beach. Here, on either side of a mass of smooth weathered stones, we saw seams of dark igneous rock penetrating the coarse conglomerate where cooling contraction had occurred. The regular geometric patterns of such chemical 'crystalisation' was clearly shown, some forming rough hexagons as in the famous Irish coastal formation.
Seaweed eating sea urchin
Seaweed eating sea urchin


Next we found two beautiful sea urchin shells. They were of two distinct species, each related to the common 5 pointed starfish. The round one lived off seaweed and had 5 concentric teeth around a central mouth which masticated the food. The mouth apparatus could be extracted from the broken shell revealing a remarkable pearly and symmetrical structure Mr Hutton told us was called the 'lantern of Aristotle'. The other ovoid urchin is rarely ever seen alive since it spends most of its time below the sand. Still with the 5 sectors, an off-centre mouth took in quantities of sand which it sifted to extract the nutrients while the waste sand was excreted. The mollusc was propelled along by short, stiff hairs all over its 100mm body. Urchin eggs are eaten by various Pacific peoples who consider them a delicacy. They are called 'ooni' in Japan.
Sand eating sea urchin
Sand eating sea urchin


One of the children found a dead crab on the beach. Mr Hutton said it was paradoxically called a 'double headed crab'. While looking like a normal baby crab, it was originally used as bait for catching the prized LHI 'double-headed fish'. The crab lives in burrows during the day, eating most of the litter left on the beach when it comes out at night (it was mostly seaweed and blue bottles that day). A large limb of driftwood blown up onto the sand was covered in so-called 'goose barnacles'. No relation to geese or barnacles, they were in fact an extraordinary variety of solitary crab which lived its whole life in a double baby clam shell, bound to the host wood by a strong attachment thread.

We were then given a tutorial on bluebottles. These singular creatures have two common varieties in the waters of Lord Howe. The ones we associate with long stinging tendrils, 'Man-o-war' species, feed on small fish or other animals which get paralysed and then raised up to the body where they are digested. The smaller bluebottle variety 'by-the-wind sailor' has both right and left handed square-rig 'sails' and are thus wind propelled in two different directions - and amazing evolutionary advantage. They have short stingers aimed at tiny organisms floating in the water. Blue bottles normally breed in huge colonies mid-ocean and these can be several kilometres across. Being propelled only by the sea and wind, the island never has bluebottles on both sides at the one time.

The island's sands are made up of 100% corals and shells in contrast to mainland sand with over 50% silica, quartz and other non-organic elements. The latter is best for building and so, for construction on the island it is imported, like almost everything else.

We now turned our attention to birds, not upwards, but downwards as the first species we encountered were nesting right there on the sand! Due to the absence of humans or other predators, most native species show a total lack of fear. 'Wild cats', introduced in the 1800s, have now been eradicated, finally allowing the return of ground nesting birds on the main island. Goats were also finally removed, allowing the return of much of the native vegetation.

Sooty tern with egg (up to 24% of its own weight)
Sooty tern with egg (up to 24% of its own weight)


Our sand nestlings were 'Sooty terns' with their enormous eggs, being up to 25% of their body weight. White terns, Black Noddys, buff-banded rails and the Emerald Dove were other common species, the latter having deep green iridescent British racing green middle plumage. Currawongs are also common and they have a habit of dive bombing unsuspecting tourists. A small local kingfisher is smaller than the kookaburra.
In June 1834 permanent settlement of the island began with three Englishmen and their Maori wives. They initially hunted mutton birds whose burrows are still seen all around the island. Some of the grandest Norfolk Island Pines date from this time. A stand of them at North Bay were apparently planted by school children in the 1930s. There is an active plan to rid the island of non-native trees and all saplings have been cut down. Helping this move, local nesting birds? droppings have burned the foliage below, killing the trees in some cases.
Lord Howe Island was named after Richard Howe, first Lord of the British Admiralty. It was first sighted by Europeans (or possibly by any human beings) in 1788 by HMS Supply, captained by Henry Lidgbird Ball. His name was given to the volcanic pinnacle 16 km south of the main island as Balls Pyramid (apostrophes were eliminated from all Australian place names in the middle of the 20th century). Highly recommended, especially if you can get a frequent flyer booking or a package deal off season.

Written by Andrew Byrne following a relaxing week on the island in October 2007.

More references: http://en.wikipedia.org/wiki/Lord_Howe_Island
Lord Howe Island from the summit of Mt Gower
Lord Howe Island from the summit of Mt Gower


Mt Lidgbird and Mt Gower in cloud
Mt Lidgbird and Mt Gower in cloud


Mt Gower from Old Settlement beach. Island Trader just visible
Mt Gower from Old Settlement beach.
Island Trader just visible


Mt Lidgbird (777m) and Mt Gower (875m)
Mt Lidgbird (777m) and Mt Gower (875m)


Typical forest track with Kentia Palms
Typical forest track with Kentia Palms


Masked booby
Masked booby


The extended family at 80th birthday of John Justinian Byrne (minus Peter & Allan) 2006
The extended family at 80th birthday
of John Justinian Byrne
(minus Peter & Allan) 2006


Last year's family T-shirt emblem
Last year's family T-shirt emblem


Looking towards North Bay and Mt Eliza
Looking towards North Bay and Mt Eliza




 

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