VU
Magellanic Plover Pluvianellus socialis



Justification

Justification of Red List category
This species appears to be naturally rare; recent surveys found that the global population is small and likely numbers just 330 mature individuals. The population trend however is thought to be stable. It is therefore assessed as Vulnerable.

Population justification
The species appears to be rare and not abundant. A thorough census of 180 sites carried out in December 2021 over the breeding range detected 264 mature individuals (Imberti and Matus 2023, Imberti et al. 2023). Considering that this census surveyed c.80% of the breeding range, the total population is best estimated at 330 mature individuals. These values were somewhat confirmed by a subsequent count of 65 sites in the non-breeding range during May 2022, which detected 300 individuals, among them 55 juveniles (Imberti and Matus 2023, Imberti et al. 2023).
To account for uncertainty and imperfect detectability, the population is here tentatively placed in the band 250-999 mature individuals, with a best estimate of 330 mature individuals.

Trend justification
The population trend has not been investigated. Anecdotal evidence suggests that the species is genuinely rare (J. Veiga in litt. 2023) and that previous estimates of 1,500-7,000 mature individuals may have been overly optimistic (Imberti and Matus 2023). Visits to a number of known sites over nearly 30 years indicate that the populations there are overall stable, despite some short-term fluctuations in numbers (Imberti and Matus 2023, Imberti et al. 2023). In the absence of evidence for any declines, the population is currently suspected to be stable, albeit at low numbers.

Distribution and population

Pluvianellus socialis occurs in extreme south Chile and south and south-east Argentina. It breeds in Patagonia. Part of the population migrates north during the non-breeding season along the Atlantic coast to the Valdés peninsula and Buenos Aires province, with single individuals being recorded in Uruguay and the Falkland Islands (Malvinas) (Pearman and Areta 2020, Castelli et al. 2022).

Ecology

It breeds on the open shores of freshwater or brackish lakes, shallow pools and sometimes rivers, in steppe-like regions up to 1,200 m. Nests are placed on pebbled or unvegetated beaches near the shore (Lishman and Nol 2012, Wiersma and Kirwan 2020). The species is partially migratory, with some individuals moving northward along the Atlantic coast during the non-breeding season (Wiersma and Kirwan 2020). Outside the breeding season, it occurs along rivers and on the coast, mostly in sheltered bays, lagoons and river mouths (Imberti 2003, Wiersma and Kirwan 2020). It feeds primarily on tiny arthropods during the breeding season, with chironomid larvae apparently forming the staple food in winter, when it forages in small flocks (Piersma 1996).

Threats

There are few apparent reasons for its scarcity. The destruction and degradation of natural grassland in Patagonia by grazing sheep is contributing to a degradation of breeding habitat, with water bodies used as troughs for livestock (Manomet, CRAL and Asociación Ambiente Sur 2023). Nests are destroyed through trampling of grazing animals (Manomet, CRAL and Asociación Ambiente Sur 2023). Shallow lagoons suitable for breeding have disappeared in the past, though it is unclear whether this is a consequence of grazing and anthropogenic alterations of the landscape, or whether this is due to natural cycles (R. Matus in litt. 2023). Further threats include predation and disturbance by feral dogs (Manomet, CRAL and Asociación Ambiente Sur 2023). It may be vulnerable to urbanisation and increasing human disturbance through recreational activities in dune habitat, accompanied by the degradation of estuarine habitat due to oil spills, garbage dumping and sewage (Ferrari et al. 2003, Manomet, CRAL and Asociación Ambiente Sur 2023, J. Veiga in litt. 2023). Lower annual rainfall and desertification as a consequence of climate change could negatively affect reproductive output (Manomet, CRAL and Asociación Ambiente Sur 2023). Furthermore, the construction of windfarms within the range could disturb or disrupt migratory routes (Manomet, CRAL and Asociación Ambiente Sur 2023). Ultimately however, there is little to no evidence that any of these threats are causing significant declines.

Conservation actions

Conservation Actions Underway
The species is listed as Endangered at the national level in Argentina (MAyDS and AA 2017). In Argentina, it breeds in Tierra del Fuego and Perito Moreno National Parks, and Bosques Petrificados Natural Monument, and it is also found in Magallanes and Laguna de los Cisnes National Reserves, Chile.

Conservation Actions Proposed
Systematically survey known sites and search for the species in potentially suitable habitat. Study the species' ecology. Research threats and their likely impacts on the population size. Develop and action plan to protect the species and its habitat. Carefully monitor the population trend. Increase protection at key breeding and wintering sites. Raise awareness for the species and its habitat with the aim of reducing disturbance to key sites.

Identification

18-20 cm. Plump and subtly coloured dove-like wader. Pale grey above, dusky lores. Broad silvery grey breast band, getting darker towards distal end. Paler throat; rest of underparts white. White tail with dusky central rectrices and narrow whitish bar on dark grey wing, visible in flight. Dark bill. Bright red eye and pinker legs. Juvenile with buffy mottling on the grey parts. Similar spp. No other wader with that shape shares its unstreaked plumage pattern. Voice Rather vocal, delivers soft dove-like whistles and other calls. Hints Tame but hard to find. Always on the move in pebble lake-shores. The voice aids in locating it.

Acknowledgements

Text account compilers
Hermes, C.

Contributors
Benstead, P., Butchart, S., Capper, D., Clay, R.P., Imberti, I., Matus, R., Mazar Barnett, J., Montero, G., Schlatter, R., Sharpe, C.J., Symes, A. & Veiga, J.


Recommended citation
BirdLife International (2024) Species factsheet: Pluvianellus socialis. Downloaded from https://datazone.birdlife.org/species/factsheet/magellanic-plover-pluvianellus-socialis on 22/02/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org on 22/02/2024.