St Helena plover (Charadrius sanctaehelenae)
|Also known as:||Saint Helena plover, wirebird|
|Size||Length: 15 cm (2)|
Classified as Critically Endangered (EN) on the IUCN Red List (1).
The St Helena plover is the only surviving bird species endemic to the South Atlantic island of St Helena (3). The upperparts are dark brown, with pale buff fringes, while the underparts are white with variable amounts of buff on the flanks (2) (4). The head is distinctively marked with a black band running across the forecrown and around the eyes, with a white stripe immediately above that encircles the head (4). One of this species’ most distinctive features is its long, thin, wiry legs, which have led to it also being known as the “wirebird” (2) (3).The immature St Helena plover lacks the adult’s head markings and has duller underparts, variably tinged pinkish-buff. Vocalisations of this species consist of short, soft kee-vit notes and a rattling alarm call (2).
The St Helena plover is endemic to St Helena, a South Atlantic island that has a total area of 122 square kilometres, of which only 30 square kilometres has been regularly used by the St Helena plover over the past 20 years (3).
The majority of the St Helena plover population inhabits mid-altitude pastureland, with the highest densities occurring in flat, dry areas with short swards (2) (3). It has been suggested that prior to the deforestation which occurred on St Helena between the 16th and 19th centuries, this species may have lived on the woodland floor (4) but this is unproven. It seems more likely that the species originally became established on an extensive coastal plain, now submerged, and its range became restricted to small, relatively open areas as sea levels rose after the last ice-age (5).
Rarely taking to the air, the St Helena plover is most commonly found in pairs, or occasionally in small groups of non-breeders, foraging in grassland or in semi-desert areas for invertebrates such as beetles and woodlice (3) (4).
Breeding takes place throughout the year, but the majority of breeding activity occurs during the dry season, from late September to January. The exact timing of this breeding peak may vary considerably from year to year, according to environmental conditions (4). The nest consists of a simple scrape in the ground, where a clutch of two eggs is laid, although single-egg clutches are occasionally seen. The eggs and nestlings suffer from high levels of predation from introduced species such as feral cats, rats and the Indian myna (Acridotheres tristis) (4), hence this species commonly lays a replacement clutch if the first clutch is lost (2). After leaving the nest, juvenile St Helena plovers disperse throughout the island in small flocks (2).
As a result of land management changes and introduced predators, the population of the St Helena plover is critically low. A census carried out during 2005 and 2006 showed that this species had undergone a decline of more that 40 percent in just five years to a mere 235 individuals (3). There has since been a small increase in numbers, however (6). The major factor suspected of causing the decline is a reduction in livestock grazing, which has become unprofitable (2), and has led to longer grass swards and encroachment by shrubland (3). This is detrimental to breeding success, as the birds rely on short swards in which to construct nests and forage. In addition to this threat, growing populations of introduced predators are consuming large numbers of this species’ eggs and chicks. To compound these existing problems, there are now plans to build an airport on St Helena, potentially reducing available habitat and causing further disturbance and degradation due to tourist activity. With its population currently at the lowest level ever recorded, the St Helena plover is perilously close to extinction, and will require careful management to ensure its survival (3).
Protected by law on St Helena since 1894, in recent years the plight of the St Helena plover has galvanised a significant amount of attention from researchers and conservationists (2) (3). Even the plan to construct the airport on St Helena has had some positive impact, as it has reinforced efforts to find out more about this threatened bird’s status and how it can be preserved (3). The airport mitigation process has also provided resources to allow restoration of some degraded, but formerly important, grassland habitat (6).
One of the organisations helping to conserve this species is The Royal Society for the Protection of Birds, which, as part of the Overseas Territories Environment Programme, is currently operating a project titled "Enabling the people of St Helena to conserve the St Helena Wirebird". Other measures to conserve this species include further scientific study, a feral cat trapping programme, as well a plan to coordinate the work of environmental NGOs through the formation of a National Trust. Hopefully, these measures should ensure that the St Helena plover’s imperilled population can begin to make a recovery (2).
To learn more about the conservation of Critically Endangered birds visit:
Authenticated (22/05/2009) by Dr Neil McCulloch, Biodiversity Unit, Northern Ireland Environment Agency.
- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
- Invertebrates: animals with no backbone.
IUCN Red List (December, 2008)
BirdLife International (April, 2009)
- McCulloch, N. (2009) Recent decline of the St Helena Wirebird Charadrius sanctaehelenae. Bird Conservation International, 19: 33-48.
- del Hoyo, J., Elliott, A. and Sargatal, J. (1996) Handbook of the Birds of the World. Volume 3: Hoatzin to Auks. Lynx Edicions, Barcelona.
- Ashmole, P. and Ashmole, M. (2000) St Helena and Ascension Island: a natural history. Anthony Nelson, Oswestry.
- McCulloch, N. (2009) Pers. comm.