Data Zone
Justification of Red List category
This species is considered Vulnerable owing to its small population. It remains threatened by land-use change, particularly human infrastructure development, and nest predation by invasive predators.
Population justification
The population was previously estimated at 200-220 mature individuals (T. Prater in litt. 2006). However, surveys in 2008, 2010 and 2015 found 373, 397 and >400 mature individuals respectively (Anon. 2015), and the population also exceeded 250 mature individuals in 2007 (F. Burns in litt. 2008). Surveys in 2016-2019 found >500 mature individuals (Leo et al. 2018), with 559 mature individuals in 2016 (S. Oppel in litt. 2015; Fisher 2016), 627 mature individuals in 2018, and 545 mature individuals in 2019 (S. Oppel in litt. 2019).
Trend justification
Surveys in 1988-1989 (giving a total of c. 450 individuals), repeated in 1998-1999, revealed large declines at all-important pastureland sites. Fieldwork in 1999-2000 and 2000-2001 suggested populations had stabilised at c. 350 adults, but survey data from 2005 and 2006 showed further evidence of a decline with an estimated 200-220 mature individuals. A full survey in 2008 located 373 adults, an increase of 16% from 2007, and there was a further population increase to 397 adults in 2010, indicating that some recovery has taken place (F. Burns in litt. 2008; S. Ellick et al. in litt. 2010), although only 350 adults were counted in 2011 (E. Duff in litt. 2011). Since 2011, the general trend has been increasing, with some fluctuations in 2014 and 2019 (S. Oppel in litt. 2019; N. McCulloch in litt. 2020). It is possible that non-native species could cause a slow decline in future, with declines suspected to fall in the range of 1-9% over three generations.
This species is the only surviving endemic landbird on St Helena (to UK) and may have declined sharply in the 1970s (Rowlands et al. 1998). Surveys in 1988-1989 (giving a total of c. 450 individuals), repeated in 1998-1999, revealed large declines at all important pastureland sites, and were not compensated by concurrent increases in lower density populations at semi-desert sites. Fieldwork in 1999-2000 and 2000-2001 suggested populations had stabilised at c.350 adults (N. McCulloch in litt. 2000, 2003), but survey data from 2005 and 2006 showed further evidence of a decline with an estimated 200-220 mature individuals (N. McCulloch in litt. 2007). Full January surveys in 2007-2010 located between 397 and 297 (averaging 353) adults (F. Burns in litt. 2008, 2010; S. Ellick et al. in litt. 2010), with 350 recorded in 2011 (E. Duff in litt. 2011). 559 mature individuals were recorded in 2016 (S. Oppel in litt. 2015; Fisher 2016). The population peaked to the highest recorded number of 627 mature individuals in 2018, while surveys in 2019 recorded 545 mature individuals (S. Oppel in litt. 2019). This indicates that a population increase has occurred and some recovery has taken place (F. Burns in litt. 2008, 2010); however, the cause of apparent fluctuations is still unclear.
Some 70% of its population occurs in pastureland, with highest densities in relatively dry, flat, short-sward pastures (McCulloch 1992, 1999). Some populations occupy semi-desert habitats (McCulloch 2009). Extended rain seasons resulting in extensive vegetation growth can delay or prevent breeding, and may, in some years, influence breeding distribution (N. McCulloch in litt. 2003). It feeds on a wide range of invertebrates. More than one clutch (of two eggs) may be laid each year and replaced if eggs or chicks are lost (Burns et al. 2013a): the proportion of a clutch that survives to independence is probably less than 20%, although adult survival is most likely high. Juveniles disperse widely in small flocks (McCulloch 1992).
Livestock grazing has become unprofitable over much of St Helena, leading to major alterations to its preferred short-sward grassland habitat. Sward growth, due to lowered densities of cattle (and sheep at two sites), and reductions in arable land may have resulted in a decline in the quality of feeding and nesting habitat at some sites (Norris and McCulloch 1999; N. McCulloch in litt. 1999). For the same reason, scrub encroachment has resulted in a major population decline at one site (Norris and McCulloch 1999), and the spread of invasive plant species has further altered habitats on the island (RSPB undated). These factors probably resulted in the significant declines of the early 1990s that continued through to 2006 (McCulloch and Norris 2001; N. McCulloch in litt. 2003; McCulloch 2009). In addition, invertebrate prey populations may be subject to large-scale, short-term fluctuations (N. McCulloch in litt. 2000). Predation has been shown to be the primary cause of nest failure (Burns et al. 2013a). Cats, rats (mostly Rattus norvegicus) and, to a lesser extent, Common Mynas Acridotheres tristis are known predators of chicks and nests. Using motion sensitive, infra-red cameras situated near to nests, cats, rats, Common Mynas and sheep have been shown to predate and disturb eggs, and nest survival rates have been found to range from 6 to 47% due to variation in predation levels (F. Burns in litt. 2008, 2010; Burns et al. 2013a). Cats have been shown to predate the largest proportion of nests, being responsible for 65% of predated nests monitored during a study in 2007-2008, followed by rats (15%) and Common Mynas (10%) (Burns et al. 2013a). Experimental control of feral cats indicated that cat control increased breeding success substantially in the semi-desert, but less so in pasture, possible due to the increase in rate numbers following the cat control (Oppel et al. 2014). However, in the four years following the standard implementation of feral cat control, the species showed the greatest increase in population size in over two decades (Leo et al. 2018). Rabbits are also becoming a problem as their abundance is destroying the nesting grounds (D. Leo in litt. 2016). In addition to the mammalian and avian predators, the non-native, big-headed ant Pheidole megacephala, was observed swamping a small number of nests in 2007-2008 and represents a potential threat (Burns et al. 2013a).
Increasing recreational use of off-road vehicles in semi-desert areas may result in disturbance and nest-destruction. Housing development has recently encroached on a number of minor breeding locations. Between 2011 and 2018, a new airport was built in one of main breeding areas, resulting in the effective loss of c.150 ha of habitat, which was compensated by improvements to grazing schemes elsewhere on the island. The airport started operating in 2018. The associated road infrastructure now leads to additional mortality through vehicle collisions (S. Oppel in litt. 2019; St Helena National Trust 2019).
The airport has been built on one of the species's breeding sites in the semi-desert of Prosperous Bay, but recent census work suggests that displacement of the plover has been minimal (N. McCulloch in litt. 2020). Associated developments may include additional housing, roads, hotels and a golf course. Current proposals are in place for a golf and accommodation complex which would impact on Broad Bottom, a major plover site. Additionally, a holiday accommodation development has been proposed at Horse Pasture, a minor breeding site (N. McCulloch in litt. 2020). New housing developments adjacent to important sites for the species may lead to increasing predation of nests by domestic animals, particularly cats. Similarly, a proposed new garbage transfer station may attract potential nest predators like rats and cats. The ability of breeding pairs to relocate is currently unknown.
The import of construction material and engineering equipment, and the potentially large increase in visitors, may lead to the inadvertent introduction of other non-native species. Extension or re-powering of the existing wind turbine development on Deadwood Plain (the most important breeding site, with 20% of the breeding population), will likely be carried out in the near future (N. McCulloch in litt. 2020).
Conservation Actions Underway
All bird species on St Helena have been protected by law since 1894 (Pitman 1965). The St Helena National Trust (SHNT) has been formed to coordinate the work of environmental NGOs (Rowe 1998), including population monitoring, ecological research, habitat restoration and raising public awareness (Smith 1997; N. McCulloch in litt. 1999), and it remains committed to the wirebird in its 2015-2020 strategy (J. Harris in litt. 2016). Over 150 ha of pastures have been enhanced for the species (J. Roberts in litt. 2010). The RSPB, The Agriculture and Natural Resource Department and the St Helena National Trust collaborated to mitigate the destruction of semi-desert habitat for airport construction by improving grazing schemes in other suitable breeding areas. This was deemed successful as the population did not decline during the construction of the airport (S. Oppel in litt. 2019).
Experimental feral cat control was carried out at sites in semi-desert and pasture between 2011 and 2013 (Oppel et al. 2014; Leo et al. 2018). This resulted in significantly improved plover productivity in semi-desert areas, but only a marginal improvement in pasture. Rat activity subsequently increased in pasture areas, but not semi-desert (N. McCulloch in litt. 2020). A new cat ordinance was passed in 2012, requiring the registration of domestic cats, which is cheaper if cats are neutered. This increased the neutering of domestic cats (S. Oppel in litt. 2019). Nest predator exclosure cages are not a suitable conservation measure for the St Helena Plover. Clutch survival was similar between nests with and without predator exclosure cages, and exclosures may have increased adult mortality (Burns et al. 2013b).
Conservation Actions Proposed
Continue to closely monitor the population on a regular basis. Increase research into the effects of pasture management and control of introduced species (McCulloch 1992, 1999; B. Rowlands in litt. 1999; F. Burns in litt. 2008, 2010). Maintain pastures as grazing land and manage appropriately (N. McCulloch in litt. 2000). Monitor changes in habitat quality closely. Restrict vehicle access to significant semi-desert sites (N. McCulloch in litt. 1999). Intensify the control of feral cats and rats around known breeding sites. Closely monitor development plans for tourist infrastructure (N. McCulloch in litt. 2010; T. Prater et al. in litt. 2011). Subject developments proposed within or adjacent to plover breeding sites to thorough environmental impact assessment of a high standard.
15 cm. Long-legged, buffy plover. Very similar to Kittlitz's Plover C. pecuarius, but is larger, has longer and thinner legs and longer bill. Black head markings do not meet on the nape and underparts are less buffy. Immature lacks head markings and is generally duller version of adult with paler underparts. Voice Soft and short, kee-vit notes. Hints Best seen at Deadwood and Prosperous Bay Plains and Woody Ridge.
Text account compilers
Clark, J.
Contributors
Ashpole, J, Benstead, P., Bird, J., Burns, F., Butchart, S., Cairns-Wicks, R., Calvert, R., Duff, E., Ekstrom, J., Ellick, S., George, K., Hall, J., Harris, J., Hillman, C., Hoffman, D., Kopij, G., Leo, D., Mahood, S., McCulloch, N., Millett, J., Oppel, S., Pilgrim, J., Prater, T., Roberts, J., Rowlands, B., Sanders, S., Stowe, T., Stringer, C., Symes, A., Taylor, J., Vickery, J. & Westrip, J.R.S.
Recommended citation
BirdLife International (2024) Species factsheet: Saint Helena Plover Charadrius sanctaehelenae. Downloaded from
https://datazone.birdlife.org/species/factsheet/saint-helena-plover-charadrius-sanctaehelenae on 27/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 27/11/2024.