Henderson Island

Henderson Island, North Beach
Henderson Island, North Beach

Henderson Island (formerly also San Juan Bautista and Elizabeth Island) is an uninhabited island in the south Pacific Ocean. It is one of the world’s last two raised coral atolls whose ecosystems remain relatively unaffected by human contact. Ten of its 51 flowering plants, all four of its land birds and about a third of the identified insects and gastropods are endemic – a remarkable diversity given the island’s size.

Measuring 9.6 kilometres (6.0 mi) by 5.1 kilometres (3.2 miles), it has an area of 37.3 square kilometres (14.4 sq mi) and is located 193 kilometres (120 mi) northeast of Pitcairn Island. It is unsuitable for agriculture, the island itself is too small and steep for agriculture and has little fresh water.
In 1902 Henderson was annexed to the Pitcairn Islands colony, now a South Pacific British Overseas Territory. It was designated a World Heritage Site by the United Nations in 1988.

There are three beaches on the northern end and the remaining coast comprises steep (mostly undercut) cliffs up to 15 metres (49 ft) in height, it has a maximum elevation of 33 metres (108 ft).
Four land bird species are endemic to the island, the Henderson Crake, Henderson Fruit Dove, Henderson Lorikeet and Henderson Reed-warbler. There are also fifteen non-endemic seabirds. Other endemic species include nine of the sixty-three plant species, four of the sixteen land snail species, and the only butterfly species.
Although Henderson is virtually uninhabitable, archaeological evidence suggests that it was inhabited by a small Polynesian permanent colony between the twelfth and fifteenth centuries until this group disappeared.
The reasons for the group’s disappearance are unknown, but are probably related to the similar disappearance of the Polynesians on Pitcairn Island, on whom the Hendersonians would have depended for many of the basics of life. The Pitcairn Polynesians may in turn have disappeared because of the decline of nearby Mangareva; thus, Henderson was at the end of a chain of small, dependent colonies of Mangareva.



Henderson Island map
Click to enlarge

Henderson Island is an elevated coralline limestone (“makatea”) island which rises as an isolated conical mound from a depth of about 3.5km. The surface of the island is coral reef-rubble interspersed with areas of dissected limestone, surrounded by steep limestone cliffs undercut on all sides except to the north.
There are three main beaches, to the north, north-west and north-east. Tidal range at spring tides is probably about 1m, and tides are semi diurnal.
The central depression is considered to be an uplifted lagoon.

Freshwater is almost completely absent, only occurring as drippings in caves, and as a brackish spring on the north shore exposed at half tide, rising from a crevice in flat rock, large surfaces of which compose the face of the beach. The surrounding ocean tidal range is about one metre at spring tide.
The geology of the island is limestone from the late Tertiary age. It is also suggested that much of the inland topography may be karst features.
Fresh water has been found at the north end of Henderson island, running from a cleft in the rock at half-ebb tide, but not visible at high water. Another source of supply is on the north coast about 1 mile from the NW point of the island, spouting from the roof of a low cave situated just above high water mark. This cave is known as Lone Frigate Cave and has been the site of archaeological excavations.

The island has a spectacular surrounding reef visible at low tide. This fringing reef is at least 200m wide to the north, north-west and north-east sides of the island, backed by a wide beach. Reefs off the north and north-east beaches are seawardly sloping reef platforms without reef crests, and are not typical fringing reefs.

Coral cover is about 5%, dominated by Pocillopora with Millepora becoming dominant at depths greater than 7m. Submassive Acropora colonies are also present on the buttresses and solid substratum. In total, 19 genera and 29 species of coral were collected in 1987. There are two narrow channels through the reef on the north and north-western coasts.



Henderson IslandThe flora of Henderson Island contains some 63 native higher plants. Perhaps 20 bryophyte species and 30 lichen taxa occur. Of the higher plants, nine occur nowhere else. The flora of Henderson is derived largely from the west, species having mainly island hopped from the Indo-Malaysian basin.
Some of the species are characteristic of eastern Polynesia, there are strong affinities with the Austral Islands and the Marquesas. The occurrence of tall, woody members of the daisy family (Bidens hendersonensis and Senecio stokesii) show some affinities with an essentially southern relict flora.

Apart from five species bordering the beaches, including coconut palms, the vegetation is undisturbed. Henderson Island is covered by 5–10 m tall tangled scrub forest, more thinly covered in the central depression. It has 51 native species of flowering plants, ten of which are unique to the island (endemic).
Dominant tree species include coconut, Pandanus tectorius, Thespesia populnea, Tournefortia argentea, Cordia subcordata, Guettarda speciosa, Pisonia grandis, Geniostoma hendersonense, Nesoluma st.-johnianum, Hernandia stokesii, Myrsine hosakae, and Celtis sp.

Henderson has three main beaches, the strandline species which occur there are all widespread Pacific or Indo-Pacific species, which probably arrived by flotation. In the embayments behind the beachfronts, a beach swale forest occurs, but the most diverse forests are found on the top of the raised coral plateau. The typical closed forest is dominated by the widespread Pisonia grandis, with several other species such as Celtis pacifica, Nesoluma st-johnianum (endemic to Henderson) and a wide variety of additional species.

The shrub layer is sometime sparse, but dominated by the Psydrax odoratum and the endemics Ixora fragrans and Geniostoma hendersonense.
The ground layer is dominated by ferns and the endemic Peperomia hendersonensis. Senna glanduligera, Bidens hendersonensis and Senecio stokesii seem to favour gaps in the canopy. Many of the larger trees are semi-decumbent, with trunks often running horizontally- this means that walking on the plateau involves passing through tree crowns; the canopy generally only reaches 10 m.
Add to this the occurrence of lianas, and your have a fairly impenetrable thicket to get through. The best developed soils occur in this species-rich Pisonia forest.
Towards the island centre the remains of the former shallow lagoon can be found. The vegetation is often more shrubby and open here, with poorly developed soils over coral sticks.

Where closed forest occurs, it is more species poor than the typical Pisonia forest, and is co-dominated by Xylosma suaveolens. The far southern part of the island is extremely exposed to salt spray and wind- the vegetation is short and stunted, and consists mainly of salt-tolerant species.

In addition to the native species, Polynesian settlers introduced a variety of species. These include plants of religious and medicinal value, in addition to food plants. Some of the latter, such as the swamp taro, no longer occur, but are known from sub-fossils found in areas that were cleared by Polynesians for garden areas- now long since revegetated.

The vegetation of Henderson is almost unique for a raised atoll in that it shows very little sign of human disturbance- many raised atolls have been devastated by mineral exploitation. Indeed, it was a geologist who made the first comprehensive collection of plants from Henderson during survey work, thankfully no phosphate exploitation has occurred on Henderson.



Fairy Terns
Fairy Terns on Henderson

Henderson Island is one the few places in the world with an ecology virtually unaltered by man. This permits the study of the dynamics of insular evolution and natural selection. Despite being reported as “infested with rats” (the Polynesian Rat [Rattus exulans], which is a good deal smaller than the Brown Rat), Henderson is particularly notable for plants and land birds, endemic to the island. Studies of piles of bones left in caves by Polynesian visitors have determined that several species of birds became extinct due to their presence.

All four of the island’s land birds are endemic: the Henderson Fruit Dove (Ptilinopus insularis), the flightless Henderson Rail (Nesophylax ater), Henderson Warbler (Acrocephalus vaughani taiti) and Stephen’s Lorikeet (Vini stepheni). Seabird species are numerous on the island, with ten species breeding on the island: Blue-grey Noddy (Procelsterna caerulea), Brown Noddy (Anous stolida), Fairy Tern (Gygis alba), Herald Petrel (Pterodroma arminjoniana), Kermadec Petrel (P. neglecta), Murphy’s Petrel (P. ultima), Phoenix Petrel (P. alba), Masked Booby (Sula dactylatra), Red-tailed Tropicbird (Phaethon rubicauda) and the Shearwater (Puffinus pacificus).

There are no native species of land mammal. All four of the island’s land birds are endemic: the flight less Henderson rail Nesophylax ater, Stephen’s lorikeet Vini stepheni (R), the Henderson fruit dove Ptilinopus insularis, and the Henderson warbler Acrocephalus vaughani taiti. Very little information is available on either the ecology or the status of these four birds.

Fifteen seabirds have been recorded, at least nine of which are thought to breed on the island; Murphy’s petrel Pterodroma ultima, phoenix petrel P. alba, herald petrel P. arminjoniana, Kermadec petrel P. neglecta, shearwater Puffinus pacificus, masked booby Sula dactylatra, red-tailed tropic bird Phaethon rubicauda, brown noddy Anous stolida, blue-grey noddy Procelsterna caerulea, and fairy tern Gygis alba.
Other terrestrial species are also poorly recorded and understood (including lizards and skinks as well as invertebrates), and it is likely that the invertebrate fauna is much larger, including several more endemics.

A new species of hawk-moth was identified in 1986, which is significantly different from any described hawk-moth.
Various records of the marine and littoral fauna have been made: Species of particular note include coconut crab Birgus latro (R) (identified from remains collected in 1987), at least two coenobite species (one of which was found to be the commonest crustacean on the island in 1987), and spiny lobster Panulirus penicillatus (CT).
Green turtle Chelonia mydas (E) occasionally nests on the island. Collections of marine molluscs and sponges and of as yet unidentified caridean shrimps (mostly Alpheids, probably comprising 5-8 species), were made in 1987.

An unidentified holothurian is common on the northern reef flats, and an echinoid Heterocentrotus sp. (possibly H. trigonarius) is locally abundant on the sloping marginal reefs and shallow reef flat of the northern beach. Fish are sparse, with Caranx lugubris being the most common and obvious species.
From the sea Henderson Island appears to consist of a level plateau, about 100 feet high, extending above the cliffs; but in actual fact the surface is cut up by innumerable sharp coral pinnacles, covered with dense undergrowth.

The soil consists almost entirely of decayed vegetation and supports a very limited range of trees and plants. A few coconut, lime and orange trees have, however, been planted on the beach by the Pitcairn Islanders, and David Young, a former Chief Magistrate of Pitcairn, who knew the island well, told H. E. Maude, O.B.E. that there were five or six acres of comparatively good soil in the north-east corner, where crops of potatoes had been grown.


History of Henderson Island

Henderson Island, north beach & caves
North beach & caves

Archaeological research has proven that Henderson had been colonised by Polynesians, however when it was discovered by Pedro Fernandez de Quiros in 1606 he stated that the island was uninhabited. Had Polynesians been living on Henderson in 1606, they most certainly would have made themselves known to Quiros.

Three crew members landed on Henderson with a small boat and came back with an unripe pine fruit (probably a fruit of Pandanus tectonius, screw pine, which grows on the island). Henderson, did support a permanent tiny population of perhaps a few dozen people. A huge buried kitchen-midden–an accumulation of shells and of bird and fish bones and other garbage left behind from generations of people feasting–runs 300 yards along the beach. Every cave and rock shelter near the coast with a flat floor and accessible opening–even small recesses only two by three yards wide, barely large enough for two people to sit there protected from the sun–contained human debris testifying to former habitation.
Charcoal, piles of stones, and relict stands of crop plants showed that the northeast part of the island had been burned and laboriously converted to garden patches where crops could be planted in pockets of soil.

Among the crops and useful plants that the settlers must have introduced intentionally were coconuts and bananas, several species of timber trees, candlenut trees whose nut husks are burned for illumination, hibiscus trees yielding fiber for making rope, and the ti shrub.
The latter’s sugary roots serve only as an emergency food supply elsewhere in Polynesia but were evidently a staple vegetable food on Henderson.
Ti leaves could be used to make clothing, house thatching, and food wrappings.

Analyzed pieces of volcanic glass found on Henderson originated at the Down Rope quarry on Pitcairn. Most of Henderson’s basalt adzes also originated on Pitcairn, but some came from Mangareva. On Mangareva itself, although far fewer searches have been made for stone artifacts there than on Henderson, some adzes were also evidently made from Pitcairn’s high-quality basalt. Conversely, of the vesicular basalt stones excavated on Henderson, most came from Mangareva, but a minority were from Pitcairn.

Henderson itself also suffered environmental damage that reduced its human carrying capacity. Half its species of land birds, and colonies of four of its species of breeding seabirds, were exterminated. Those extinctions probably resulted from a combination of hunting for food, habitat destruction for gardens, and depredations of rats that arrived as stowaways in Polynesian canoes. Today those rats continue to prey on the remaining seabirds, which evolved in the absence of rats and so are unable to defend themselves.
Thus, environmental damage, leading to social and political chaos and to loss of timber for canoes, ended southeast Polynesia’s interisland trade, cutting Mangarevans off from Pitcairn’s sources of high-quality stone for making tools. For the inhabitants of Pitcairn and Henderson, the results were even worse: eventually no one was left alive on those islands.


European Discovery
Henderson Island
Henderson Island was sighted by Pedro Fernandez de Quiros, a Portuguese navigator sailing for the Spanish King, on January 29, 1606. He named it “San Juan Bautista”.
Some scholars once thought that Henderson Island was first re-discovered in 1791 by Captain Edwards of the Pandora (searching for the Bounty mutineers), who named it Lord Hood’s Island. This claim can be easily disproved, for Captain Edwards described his discovery as lying in latitude 21 deg. 31 seconds S. and longitude 135 deg. 30 seconds W. and being a low lagoon island covered with wood; it was almost certainly one of the Tuamotu Islands.

January 17, 1819 Henderson Island was re-discovered by Captain James Henderson of the British East India merchant ship Hercules. The Herculescalled at Pitcairn on January 18, 1819, and had sighted Henderson the previous day.
The Hercules was engaged on trading voyages between India and South America and was instrumental in commencing the long association of the Society for Promoting Christian Knowledge (at first through their Calcutta committee) and the Pitcairn Islanders.

March 2, 1819 Henderson Island is sighted by Captain Henry King of the ship “Elizabeth.” He is unaware of Captain Henderson’s discovery in January.
He lands on the island: ” The British colours were displayed on the island and greeted with three cheers, and a bumper of grog was drunk to the health of His Majesty. The ship returned the compliment, by hoisting her colours and performing the same ceremony.

While these ceremonies were performing, a proper person was employed in carving the ship’s name and other particulars upon a tree, near the spot where we landed.”
For some years both the names “Elizabeth” and “Henderson” are applied to the island.
Aaron Mitchel and Company’s whale ship Oeno of Nantucket, 328 tons, Captain George B. Worth in command discovers Oeno Island on Jan 26th 1824.

Oeno is a low atoll which is 3.5 km in diameter and 120 km NW of Pitcairn The remaining uninhabited island in the Pitcairn group is Ducie Island which was discovered by Quiros in 1606 and named “Encarcnacion”, (another sorce says he named it “Luna puesta”) and rediscoverd by the infamous Captain Edwards of the HMS Pandora in 1791. Ducie is a low islet 300 east of Henderson Island. Captain Edwards and his ship the Pandora were sent to capture the Bounty mutineers – they were on Pitcairn, which he couldn’t find. Many shipwrecks have occurred on Oeno and Ducie Islands.

In 1825 H.M. Sloop Blossom is sent to determine whether Ducie and Elizabeth (Henderson) Islands are the same island. H.M. Sloop Blossom visits Pitcairn and both islands, and also Oeno, where a sailor is drowned when a boat is smashed on the reef.

H. E. Maude writes that the true story of the ill-fated American whaling ship Essex of Nantucket, sunk by a 40- foot sperm whale in the vicinity of the Marquesas in 1819, provid(ed) material for Herman Melville’s immortal story, Moby Dick. The survivors landed on Henderson, after sailing in an open boat from the distant site of their shipwreck. Most of the party departed on December 20 1820. Two of the boats sail 4.300 miles towards South America before being rescued. The third boat becomes separated from the others and is found by a passing ship earlier.
The three crew members that remained on Henderson Island were picked up by the English ship Surrey, dispatched from Valparaiso, on April 18 1821 after spending 107 days on the island.

Owen Chase, one of the survivors of the Essex boat crew voyage to South America states that while on Henderson we had observed the name of a ship, ‘the Elizabeth,’ cut out in the bark of a tree, which rendered it indubitable that one of that name had once touched here. There was, however, no date to it, or anything else, by which any further particulars could be made out.

Six human skeletons were discovered in a cave by the Essex crew. There is, however, another report, written by Thomas Chapple, one of the Essex survivors, from the Religious Tract Society in 1830, that eight skeletons (as versus six) were found by the Essex crew. There is also believed to be a report of a finding of skeletons even before the Essex survivors arrived at Henderson. Six skeletons were again found on Henderson Island on Saturday, March 29, 1958 in a cave on the northeastern coast.