13 January 2008

Rising Seas a Threat to Nesting Haven for Birds at Ducie Island

A slight change in sea water levels may have a dramatic effect at Ducie Island, a group of four atolls in the South Pacific Ocean. The tiny specks are a haven for oceanic birds to nest.

Ducie is an important location for seabirds with around a dozen species breeding on the atoll, including what is thought to be the world's largest breeding colony of Murphy's Petrel (Pterodroma ultima) with around 250,000 pairs. - Oceandots

Ducey Island - with a land area of 0.7 km2 - is among a group of islands, including Henderson, Pitcairn and Oeno Islands, called the Pitcairns, in the deep Pacific along the Tropic of Capricorn. Peru is the closest land mass.

Ducie Island was first known in the annals when discovered by Quiros in 1606, and named Encarnacion.

The name changed to recognize Lord Ducie back at the home country estate, by a Captain Edwards looking for the Bounty mutineers in 1791.

The place was visited by the United Kingdom government in 1825. Frederick William Beechey was the Commander of the good ship Blossom, on an United Kingdom expedition... [Map from Pacific Islands andbook]

"On the 25th November in 24..20S. Latitude & 118..30W Longitude we had the NE trade wind and on the 28th, saw Ducies' Island, stood off and on during the Night, and the next morning got close to it and sent in the boats. This is a low coral Island not higher than 20 feet, of a rounded triangular form, covert with luxuriant shrubs and some trees. Its' greatest length, that is from the North to the South point, does not exceed a mile, and from the Mast head we observed that the land forms but a small part of what at first appears it's bulk, as it encloses or is more like an embankment round a large lake which communicates with the sea by a narrow entrance near the South Point, off which the Surf breaks over a coral reef for 1/4 of a mile. Reefs also extend for a short distance from the North & NW points with 90 fathoms of water near them.
"The boats after making the circuit of the Island, returned with the report that the Island is entirely surrounded by breakers, inside of which the water is perfectly smooth and that the only part where there is a possibility of getting through them with safety, is at the entrance to the Lake at which place, for an extent of 40 yards, the sea would occasionally cease breaking & probably afford a passage were there time to attempt it. The water was so clear that they distinctly saw the bottom in thirty five fathoms; they had 25-fathom close outside the breakers, & the ship could get no bottom 1/2 mile off shore with 300 fathoms of line. We saw several Bonitos and grey sharks, & great numbers of Gannet, Shearwater, boobies and Boatswains' birds. The Beach is composed of coral & shells, the Island uninhabitated, situate in 24o .. 30' S. Latitude & 124o..55' W. Longitude, & could not be seen off deck farther than 7 Miles."

The zoology publication for the voyage has additional details on birds, in the ornithology section by N.A. Vigors.

Trochilus mellivorus. White-bellied Humming-bird.
A pair of birds, apparently melliphagous, were brought from Pitcairn's Islands. But they unfortunately are so mutilated as to preclude any attempt at description or reference.
Tachypetes aquilus. Frigate bird.
The species was observed at Pitcairn's Island, ...
Tachypetes leucocephalus. White-headed Frigate Pelican.
... observed also off Ducie's Island, "but soaring at a considerable height, and not approaching the ship."
Sterna alba. White Tern.
This species was found abundantly at Pitcairn's island.
Sterna stolida. Noddy.
This species was observed at various places during the voyage - ... at Ducie's Island; at Pitcairn's Island, Dec. 1825 ...
Sterna Panayensis. Panayan Tern.
... species, which was found at Ducie's Island, is the same as generally to to that species.

In 1867, the Australian government has a request for a license, John C. Daggett, to extract resources.

"The Island referred to is in Latitude 24o40' South Longitude 124o48' West called Ducer Island and is required by mee for the purpose of workings and removing guano there from." The name Ducie was written in left margin.

"The three islands were formally annexed by Britain in 1902. In 1937 H.M.S. Leander visited each, and erected on each a signboard, affirming British sovereignty." They were made part of the Pitcairn administrative district in 1938, according to the 1944 Pacific Islands Handbook

A government expedition mapped the Pitcairns, notable indicating on the map that Ducie had a maximum elevation of 12 feet, as shown on the 1940s era map.

After G.R. Williams surveys during eight weeks of studies in October-November 1959, the first bird list for Pitcairn Island and the Elizabeth Islands was published. Another prepared in the early 1990s, reviewed the knowledge of endemic species at Henderson Island where surveys had been done a few years previous.

Blue Noddy (Procelsterna cerulea), juvenile.

White (or Fairy) Tern (Gygis alba), adult.

Red-tailed Tropicbird (Phaethon rubricauda), juvenile.

Murphy's Petrel (Pterodroma ultima), adult.

Images courtesy of Angela K. Kepler.

Specific visits to Ducie Island to study the birds were done by Angela K. Kepler at six different times of year over about 5 years in the 1990s. "Ducie is one of the most remarkable islands in the entire world and one of the very very few that is still totally pristine," she said. Her compilation indicates the occurrence of a greater number of species than previously known.

Birds noted for Ducie Island
Oeno Petrel
Kermadec Petrel (Putuputu; general for petrel)
Phoenix Petrel
Herald Petrel
Christmas Shearwater
Fairy Tern (white bird)
Common Noddy (Nordie = noddy)
Gray Ternlet (Patru = petrel)
Red-tailed Tropic Bird (tropic bird, Bos'un bird)
Masked Booby (Gahnet = Gannet)
Red-footed Booby (Taitai or Austin bird)
Greater Frigate Bird (hawk)
?Spotless Crake (Chicken bird)
?Bristle-thighed Curlew (Shipmate)
Sanderling; March 1922, summer migrant
Williams. 1960. The birds of the Pitcairn Islands, central south Pacific Ocean. Ibis 102(1): 58-70.
Breeding birds (most important ones by far indicated with an asterisk):
* Murphy's Petrel
* Kermadec Petrel
* Phoenix Petrel
* Herald Petrel
* Henderson Petrel
* Christmas Shearwater
Red-tailed Tropicbird
Masked Booby
Red-footed Booby
Great Frigatebird
Sooty Tern
Fairly (White) Tren
Blue Noddy
Brown Noddy
Black Noddy
Long-distance migrant from New Zealand: Long-tailed Koel
Migrants from the Arctic:
* Bristle-thighed Curlew
Wandering Tattler
Information courtesy of Angela K. Kepler

A visit in April 1998 shows scenes on the island.

At some historic time, visitors brought rats that had a dramatic impact on the island avifauna. In 1995, the island was deratted according to UK officials.

No details are available on the current state of things on Ducie Island. There have been international indications that ocean levels will change with conditions of the global climate.

Low atolls, such as Ducie Island - and other distinct island habitats - can readily indicate localized impacts to birds due to rising water levels.

Administratively Ducie island is part of the Pitcairn Islands, one of the UK's Overseas Territories. The Pitcairn Island Council has responsibility for day-to-day administration of the island, the Pitcairn Government based in New Zealand looks after the Islands' interests in a wider international context. - Office of the Governor of Pitcairn, Henderson, Ducie and Oeno Islands; Wellington, New Zealand

There is a pending ham-radio operators expedition to the Island in latter February.

Tree Heliotrope (Tournefortia argentea) on Ducie Island, Pitcairn Islands. Image Courtesy of Angela K. Kepler.


Ducie Atoll: Its History, Physiography and Biota

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