Data Zone
Justification of Red List category
This species was formerly widespread, but is now restricted to very few islands where it is undergoing a continuing decline owing to the effects of introduced species, and to a lesser extent, habitat degradation. Rat-free populations numbering more than 100 individuals exist only on three islands, and populations are highly vulnerable to sea level rise. As such, the species is assessed as Endangered.
Population justification
Rat-free populations of more than 100 individuals exist only on three islands, with populations on other islands persisting at very low numbers. The population is estimated to number 600-1,000 individuals on Tenararo, >530 individuals on Morane and 150 individuals on Tahanea (Thibault and Cibois 2017). There are also estimated to be 35 individuals on Anuanuaro, several tens on Reitoru, no more than a dozen on Raraka and at least one pair on Marutea South (Thibault and Cibois 2017). This gives a total population estimate of approximately 1,600 individuals, roughly equating to 1,100 mature individuals. However, mark recapture in 2015 has suggested that numbers on Tenararo and Morane may have been overestimated and these populations may number less than 500 birds each (R. Pierce in litt. 2023). As such, the population is placed here in the band 700-1,100 mature individuals.
Trend justification
There have been an increasing number of nil returns when islands where small numbers had been reported are re-surveyed, implying a continuing population decline correlated with the spread of rats and cats that is still ongoing in association with the development of Tuamotu (Pierce and Blanvillain 2004, Thibault and Cibois 2017). Given evidence of rapid declines on Tahanea (through starvation) in 2011 following an entry of saltwater into the water tables of the islets caused by a strong swell [Pierce et al. 2003, 2016; Pierce and Blanvillain 2004]) and ongoing evidence of habitat damage caused by swells (R. Pierce in litt. 2016), the effects of climate change, particularly sea level rise, are likely to be a significant threat to the species in the future. Overall the population is inferred to be in decline, but the rate has not been quantified.
Prosobonia parvirostris is endemic to the Tuamotu Archipelago, French Polynesia, where breeding populations occur on Tenararo, Morane, Tahanea, Anuanuaro, Reitoru, Raraka and Marutea South (Thibault and Cibois 2017). The species is also possibly breeding on Vahanga, Maria, Vanavana and Raroia (Thibault and Cibois 2017). Records of small numbers of individuals from other islands may refer to visiting (rather than established) birds (Blanvillain et al. 2002, Thibault and Cibois 2017).
It is found on upper beaches of coral rubble and sand amongst dwarf shrubs (especially Scaevola, Messerschmidti and Guettarda) and scattered tall shrubs, as well as in adjacent areas of shrubland and interior of forest, especially open forest (Pratt et al. 1987, Pierce and Blanvillain 2004). Dense stands of Pandanus and coconut trees Cocos nucifera are avoided (Pierce and Blanvillain 2004) when they outcompete the shrub layer. The species is regularly reported along atoll shorelines and lagoon edges (Pratt et al. 1987), but it is thought they only frequent these habitats when attracted out of curiosity to the observers (Pierce and Blanvillain 2004). It is non-migratory but may visit islands where it does not nest (Pratt et al. 1987). Food, which comprises mainly invertebrates, seeds, nectar and some plant material, is gleaned from the vegetation of scrubs and trees and also from the surface of the ground and in leaf litter (Pierce and Blanvillain 2004, M. H. Burle in litt. 2012).
The introduction of rats, particularly Black Rat Rattus rattus, and cats Felis catus, has eliminated the species from all but the most infrequently visited islands in the archipelago (Pratt et al. 1987, Pierce and Blanvillain 2004). Other invasive species also now pose a threat as they colonise Tuamotu. Yellow Crazy Ants Anoplolepis gracilipes are established on many islands including Mangareva and Turea, both of which are departure islands for several islands inhabited by the Tuamotu Sandpiper (Pierce et al. 2015). Meanwhile, the establishment of coconut Cocos nucifera plantations is thought not to be a threat unless native undergrowth is also cleared (Pierce and Blanvillain 2004) or outcompeted by seedlings when plantations are not harvested (M. H. Burle in litt. 2012). Abandoned coconut plantations are thus another important cause of habitat loss, for instance on many islets of Tahanea and possibly, to a much greater extent, on Tenararo (M. H. Burle and D. B. Lank in litt. 2012, Pierce et al. 2015). Moreover, the establishment of coconut plantations can increase the frequency of human visits to islands and consequently the likelihood of predator introduction (Pierce et al. 2003, Pierce and Blanvillain 2004). An additional concern is that visiting birdwatchers, as well as local fishermen and Coconut Crab Birgus latro harvesters, may accidentally introduce rats, invasive ants, weeds, etc. to Tenararo and Morane (Pierce et al. 2003, P. Raust in litt. 2007). The dramatic effect of a swell witnessed in 2011 (a 55% population crash in less than a month due to starvation as a result of vegetation, and possibly arthropod, die-out) proved the negative effects of sea level rise to the species. There was also evidence of habitat damage caused by swells at Tenararo and Vahanga in 2015 (R. Pierce in litt. 2016). Although swells are a natural and likely regular phenomenon, populations are so small and isolated that they now affect the survival of the species as a whole (Thibault and Cibois 2017). The effects of climate change, particularly sea level rise, are therefore likely to be a significant threat to the species in the future.
Conservation Actions Underway
Information on this species has been collected as a result of expeditions in 1999 and follow-up work in 2001 and 2003, as well as work conducted on Tahanea in 2008/2009 and 2011 (M. H. Burle in litt. 2012). Rattus exulans were eradicated from three islets within the atoll of Tahanea in 2011 (Pott et al. 2014). In 2015, SOP-Manu undertook cat and/or rat eradication on Vahanga, Tenarunga and Temoe and other islands in the Gambiers, with technical support from the New Zealand Department of Conservation, Pacific Invasives Initiative, BirdLife International, SOP and Island Conservation and funding from CEPF and EU. The project was deemed successful during the 2017 survey and may enable natural recolonisation on Vahanga and Tenarunga (from Tenararo) and reintroduction is planned for Temoe (Withers 2017).
Conservation Actions Proposed
Survey islands where additional populations may occur (Thibault and Cibois 2017). Develop an action plan for this species (Pierce et al. 2016).
With owners, plan and implement management of habitats on key islands, particularly Tenararo and Vahanga. Maintain the predator-free status of Morane and Tenararo by restricting access. Maintain strict biosecurity at sources, vessels and arrival points at islands with Tuamotu Sandpiper to prevent accidental introduction of Yellow Crazy Ants, rodents and other invasives. Monitor the recolonisation of nearest islands (Vahanga and Tenarunga), improve biosecurity and initiate plans for translocation to Temoe. Identify suitable islands for further recovery including Henderson Island (Pitcairn Group, failed rat eradication 2011), and potentially also Reitoru. Raise awareness for preventative activities and biosecurity generally in the Tuamotu and Gambiers. Involve local people in the implementation of the recovery plan, with the species as its emblem, so that they associate it with increased coprah and Coconut Crab yields which will result from rat eradication.
17 cm. Small sandpiper with very short, sharp bill. Variably mottled and streaked with dull brown, with bold white superciliary stripe. Black bill. Similar spp. Sanderling Calidris alba larger and much paler. Voice Frequent alarm call: a medium-pitched repetitive ti-ti-ti-ti. Song: a more elaborate lower pitched long-lasting trill.
Text account compilers
Vine, J.
Contributors
Blanvillain, C., Burle, M., Lank, D.B., Pierce, R. & Raust, P.
Recommended citation
BirdLife International (2024) Species factsheet: Tuamotu Sandpiper Prosobonia parvirostris. Downloaded from
https://datazone.birdlife.org/species/factsheet/tuamotu-sandpiper-prosobonia-parvirostris on 23/11/2024.
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 23/11/2024.