St Helena’s unique wirebird features on the latest “red list” of the world’s critically endangered species, thanks to threats from the airport and new tourist developments.
Its recovering population should have been enough for its threat status to be relaxed, but it was argued that it should remain on the danger list to give time for experts to see how it copes with the arrival of the airport.
Four other unique island species remain on the red list – but two are thought to be extinct.
The listing for the wirebird – also known as the St Helena Plover – says:
“This species is classified as critically endangered because until very recently its population was extremely small and declining owing to land-use change (particularly a decrease in grazing pressure) and predation by invasive predators.
“The population has recently shown some signs of recovery, however, and if it continues to remain above 250 mature individuals and/or continues to increase or stay stable for a five-year period, it is likely to be eligible for downlisting.
“Given uncertainty over the impacts of the impending construction of an airport (which may well be significant), and given that these impacts will become clearer during 2012-2013, the status of this species should continue to be monitored closely.”
The two species thought to be extinct are the insect St Helena darter and the St Helena earwig, says the International Union for the Conservation of Nature (IUCN), which compiles the red list.
The darter has not been seen since 1963, but a lack of surveys means its survival is not ruled out.
The St Helena earwig – the largest in the world – is widely believed to have been wiped out by predators, including mice and an introduced centipede.
Some people believe the earwig has survived on Properous Bay Plain but might now be destroyed by the island’s new airport. No specimens have been seen alive since 1967, despite expeditions to find them.
St Helena Rosemary – which gave its name to Rosemary Plain – is now reduced to about 100 plants in three small clusters, on cliffs at High Hill and Lot, and between Distant Cottage and the Asses Ears
About 20 plants are also growing at Scotland and in the Castle Gardens.
A recovery plan includes establishing new colonies at Plantation, Peak Dale and the Millennium Forest, and encouraging “guardians” for other plantations.
Stocks are also being kept in the UK at Kew Gardens and the Eden Project.
The St Helena Ebony is listed as critically endangered even though it is widespread in gardens across the island – and around the world.
It was thought to be extinct until two surviving plants were spotted at a distance by George Benjamin, who died earlier this year. His brother was lowered down a cliff to reach one of the plants.
Because all the specimens around the world have been bred from those two individuals, “in-breeding” weaknesses present a continuing threat.
A hybrid variant has developed and the IUCN says the true ebony has not been “properly secured” in any gene banks in isolation from the hybrid.
A recovery plan includes establishing a new field gene bank at the Millennium Forest.
The IUCN says it has too little information on another species, the St Helena dragonet, to be able to decide whether it is under threat.
It is the smallest fish of its kind in the world, reaching only two centimetres in length.
There is also a lack of information about the endemic St Helena Wrasse. “Little or nothing is known about its biology or the status of its population,” says the official lissting. “More research is needed to determine any major threats for this species, given its very restricted range.”
Other endemic species appear on the list as vulnerable, extinct or “least concern”.
Ascension Island has two critically endangered species, including the parsley fern, which was thought to be extinct until four plants were discovered by Stedson Stroud, Olivia Renshaw and Phil Lambdon in July 2009. About 40 more have since been found.
Ironically, Ascension spurge may be suffering as a result of a programme to eradicate feral cats. Without the cats, there may be more mice and rabbits grazing on the spurge.
Tristan da Cunha’s only critically endangered species is the Tristan albatross, which has suffered a plummeting population thanks to longline fishing and chicks being eaten alive by mice. Even though the chicks are much bigger than the mice, they cannot move quickly enough to fend off their attackers. Rescue packages are planned.
On the Falklands, no species are listed as critically endangered, though Falkland rock cress is “vulnerable” and its range is shrinking, thanks to grazing.
Special ship researches island fisheries
RSPB objects to Shelco resort over wirebird doubts (note: the resort plan was approved)
Endemics for sale: St Helena’s new cash crop?
Red list counts ‘on the brink’ species – BBC
St Helena National Trust
The red list: critically endangered species (search for St Helena, Tristan, Ascension or Falkland)
St Helena earwig – Wikipedia
St Helena ebony – Kew