Data Zone
Justification of Red List category
Arenaria interpres is a widespread species with a global population of 750,000-1,750,000 mature individuals. However the species is exposed to a panoply of threats across its vast range, including habitat loss and degradation, illegal killing, disturbance and possibly reduced breeding productivity caused by factors associated with climate change. While the relative importance of these threats is unknown, monitoring data in several parts of its world—particularly in North America—indicate locally rapid declines over the past three generations. Combining often disparate trend data from across its range and weighting it according to likely regional population sizes, the global population is thought to have declined moderately rapidly, at a rate of c. 20-29% over the past three generations (18 years). It is therefore listed as Near Threatened.
Population justification
Andres et al. (2012) estimated that North American morinella and interpres totalled 245,000 but a more recent evaluation (Bart et al. in prep.) estimates a much larger total for breeding populations in Canada alone (thus excluding Alaska and Greenland from their estimates) of c.510,000 (±c.170,000) for morinella and c.460,000 (±c.150,000) interpres, thus giving a total of 650,000-1,300,000. Populations of interpres in northern Europe, Siberia etc. have variably been summed to total 184,000-320,000 (van Roomen et al. 2022, Hansen et al. 2022, Wetlands International 2023), although unlike the previous data these figures are based principally on non-breeding counts, and therefore likely contain a significant number (estimated here to be 20-30%) of immatures. Summing available data gives a global estimate of 760,000-1,524,000 mature individuals, rounded here to 750,000-1,750,000 mature individuals to account for some inherent uncertainty.
Trend justification
Trends vary across populations but a collation of available data suggests moderately rapid declines in this species over the past three generations (18 years).
In the Americas, subspecies morinella (at least c.27% of global population of the species, but possibly much greater [see below]) was estimated by Smith et al. (2023) to have declined at a rate of 46.7% over the three generations to 2019. PRISM surveys in the Arctic National Wildlife Refuge, Alaska between 2002/2004 and 2019/2022 showed a decline in the point estimate (2002/2004: 2,984, SE=1,484; 2019/2022: 811, SE = 595). A similar survey in the Teshekpuk Lake Special Area in north central Alaska showed a slight decrease in number of individuals detected in 2007/2008 (17) to 2023 (15) (R. Lanctot in litt. 2024). While less severe in rate, eBird data similarly show a decline in this population of 10.8% (4.1-16.3%) in the ten years between 2011 and 2021, equivalent to a rate of nearly 20% over three generations (Fink et al. 2023). Those wintering recorded in Audobon's Christmas Bird Count however show a broadly stable trend in all time windows (1970-2021, 1993-2021, 2009-2021) (Meehan et al. 2022). There is some uncertainty regarding the population size of A. i. morinella, with Bart et al. (in prep.) estimating a population size significantly above that of Andres et al. (2012); accordingly, this subspecies may represent a higher proportion of the global population than currently recognised.
The taxon interpres is split into five subpopulations with disparate trends. (1) The population that breeds in north-east Canada and Greenland, and winters in Western Europe and north-west Africa (c.35% of global population), is likely to have a stable trend. Nagy and Langendoen (2020) reported moderate increases in abundance from 1977 to 2018 (1.0243) and a stable trend 2009 to 2018 (0.9979); also see data in van Roomen et al. (2022: p.200). (2) Those wintering in northern Europe and West Africa (c.10% of global population) are thought to have declined rapidly between 2006 and 2018, at a rate approaching 50% over three generations (Nagy and Langendoen 2020) but data between 2015 and 2020 apparently showed little to no decline (van Roomen et al. 2022). (3) Those wintering in south-west Asia and east/southern Africa (c.15% of global population) have also probably declined extremely rapidly, with data from 12 countries across the region (excluding Oman) indicating declines at a rate equivalent to 83% over three generations between 2009 and 2018. Note, however, that counts at Barr al Hikman, Oman, showed increasing numbers over a similar timeframe (de Fouw et al. 2017), although the latter may be an artefact of improved count coverage and methodology. (4) Trends of birds wintering in South Asia (c.8% of global population) are uncertain over the past three generations, although reporting rates in citizen science data in India suggest here too the species is declining, perhaps rapidly (SoIB 2023). Finally, (5) those wintering in the Pacific and South-East Asia regions (c.5% of global population) are thought to have declined moderately rapidly. Numbers in Australia declined at a rate equivalent to 25% over the three generations to 2021 (numbers differ slightly from those published due to use of a different generation length to that used here), albeit with a fairly stable trend since c.2010 (Rogers et al. 2023), while Langendoen et al. (2021), using data from the Asian Waterbird Census, suggested similar declines of 32%. In New Zealand, Riegen and Sagar (2020) recorded a 61% decline of this species in recent national wader counts across the country when 2005-2017 numbers are compared to numbers reported 1983-1994. However, some caution is needed in these latter data, as Riegen and Sagar (2020) did not sample some key wintering sites in their later time period; thus while declines reported are probably legitimate, they may be exaggerated. Moreover, more recent data comparing numbers between 2008 and 2022 showed a broadly stable trend in New Zealand (H. Robertson in litt. 2024). In Sweden, breeding A. i. interpres apparently declined by more than 80% between 2003 and 2018 (K. Larsson in litt. 2024), and unquantified declines have also been reported from Chukotka, Russia (D. Solovyeva in litt. 2024). Migration counts from Hanko Bird Observatory, Finland, suggest a rapid long-term decline between 1979-1999 and 2020-2022, equivalent to 82%; a short-term decline of 24% is also reported in the short term (between 2010 and 2019) (Ornithological Society of Helsinki 2024, A. Lehikoinen in litt. 2024).
Combining available data sources with their relevant population size weighting yields a global population decline over the past three generations of c.24-32%. Given some extrapolation in the methods of deriving these trend estimates and some uncertainty regarding population sizes (thus what relative weight should be given to each population trend), the rate of global population decline is broadened to a bracket of 20-35%, with a best estimate of 20-29% based on the observation that in most populations estimated to be declining (including van Roomen et al. 2022, Smith et al. 2023, Rogers et al. 2023) in the most recent years of the time window analysed (typically 2018-2021), declines had evidently begun to slow such that declines over the most recent three generations (2008-2024) are probably slightly slower than those published.
Almost cosmopolitan range with large populations that span all major flyways. Vast breeding range spans much of low arctic, from western Alaska (USA) and Arctic Canada (see Bart et al. in prep) east through north and north-east Greenland, northern Europe, northern Siberia east to the Chukotsk Peninsula and Bering Sea. In winter, widespread along most of the world's coastlines.
Behaviour This species is fully migratory (del Hoyo et al. 1996). It breeds from May to early-August in solitary pairs, although several pairs may nest close together in optimal habitats along coasts or on islands (Johnsgard 1981, Hayman et al. 1986, del Hoyo et al. 1996, Snow and Perrins 1998). The species migrates in large flocks and is gregarious and sociable when feeding or roosting in winter, often foraging in close flocks of 10-100 or more individuals, especially in tidal areas (del Hoyo et al. 1996, Snow and Perrins 1998).
Habitat Breeding The species breeds near the coast or up to several kilometres inland in the high Arctic, nesting on coastal plains, marshes and tundra and showing a preference for mosaics of bare rock, clay or shingle and vegetation near water or in areas that remain damp until late summer (Johnsgard 1981, Hayman et al. 1986, del Hoyo et al. 1996, Snow and Perrins 1998). Non-breeding Outside of the breeding season the species is mainly coastal, although on migration it may occur inland along dykes or on lake shores (del Hoyo et al. 1996). During the winter it frequents productive rocky and shingle shores, breakwaters, sandy beaches with storm-wracked seaweed, short-grass saltmarshes, sheltered inlets, estuaries, mangroves swamps, exposed reefs and mudflats with beds of molluscs (Hayman et al. 1986, del Hoyo et al. 1996).
Diet Breeding On its Arctic breeding grounds the species takes Diptera (especially adult and larval midges) as well as larval Lepidoptera, Hymenoptera, Coleoptera and spiders, occasionally also taking vegetable matter early in the season (del Hoyo et al. 1996). Non-breeding Outside of the breeding season its diet consists of insects, crustaceans, molluscs (especially mussels or cockles), annelids, echinoderms, small fish, carrion and birds eggs (Johnsgard 1981, del Hoyo et al. 1996).
Breeding site The nest is a shallow depression in mud, peat or on dry ground with dense vegetation, often positioned on a slight ridge, hummock or tussock, or in cleft or shallow fissure (Johnsgard 1981, del Hoyo et al. 1996, Snow and Perrins 1998). The species usually nests solitarily, although neighbouring pairs may nest as little as 15 m apart along coasts or on islands (where abundant feeding habitats are available) (Snow and Perrins 1998).
Numerous threats have been identified, but the extent to which any of them are driving observed declines is unknown, with much more research needed before threats can be targeted for mitigation.
Climate change has been identified for several shorebird species as a threat that is driving reduced breeding productivity by a number of mechanisms (e.g. Meltofte et al. 2007, Eikelenboom 2016, Kubelka et al. 2018); more research for this species specifically is needed.
The species is exposed to additional threats on its staging and wintering grounds, particularly habitat degradation and conversion. At Barr Al Hikman, Oman, where up to 26% of the Asian-East African Flyway population has been reported to overwinter, planned urban developments, the aquaculture (for shrimp) industry, oil refineries and disturbance from fishing industries and falcon hunting were all identified as threats by de Fouw et al. (2018) and these almost certainly apply to other important staging and wintering sites in the broader region. The extent of hunting in this region is poorly known, but shorebirds are occasionally targeted (Brochet et al. 2016). The species is threatened on the south-east coast of India (Point Calimere) by illegal hunting (bird trapping), reservoir and marshland habitat alteration by salt-industries, and habitat degradation by diminishing rainfall (changing the salt regime) (Balachandran 2006). Rapid land-use change and loss of mudflats are also major threats here. It is also threatened at Walvis Bay in Namibia, a key wetland site in southern Africa, by habitat degradation (e.g. changes in the flood regime due to road building, and wetland reclamation for suburb and port development), and disturbance from tourism (Wearne and Underhill 2005). Again, these threats are probably widespread in the region.
Significant numbers of A. interpres migrate down the Yellow and East China Seas where habitat loss and hunting are plausibly significant threats. The extent of reclaimed land along the Yellow Sea coastline now exceeds the extent of remaining intertidal mudflat (Murray et al. 2014, IUCN 2023), suggesting that this may have contributed greatly to declines in this species. The rate of habitat lost to land reclamation has slowed since a peak in c. 2013, in particular in recent years due to the promised near-ceasing of land reclamation in China in early 2018 (Melville 2018); however, recent satellite data suggests that the extent of intertidal mudflat has continued to decrease, in large part due to continued reclamations in the Korean Peninsula (IUCN 2023). Mudflats have also continued to degrade in suitability for this species and other shorebirds because of the invasive alien Spartina alterniflora cordgrass, which appears to be spreading; in recent (post 2020) years, this threat has probably driven greater declines than planned land reclamation. In addition to land reclamation, coastal development and a rapid increase in the human population along the coastline of the Yellow Sea has led to widespread degradation of mudflats and coastal habitats used by this species; IUCN (2023) (and references therein) cite the following as additional drivers of mudflat loss and degradation: 'processes such as changes in sediment supply, loss of coastal vegetation associated with development...erosion, redistribution of sediments due to storms, and compaction and subsidence (sinking) caused by subsurface resource and groundwater extraction are also likely to be factors'. Offshore windfarms may have a so far unquantified impact on birds due to collisions (unlikely) and displacement and disturbance of feeding birds (more likely). Disturbance on mudflats by fishermen and others using the mudflats may also be reasonably considered a threat. Hunting is also possibly a significant threat impacting this and other shorebird species on passage (Gallo-Cajiao et al. 2020).
Conservation Actions Underway
The species is listed in Annex II of CMS. It is not listed on the annexes of the European Union (EU) Birds Directive, but is covered by the general protection regime provided by Article 1 of the Directive to all naturally occurring wild species in the EU. It is listed on Annex II (strictly protected) of the pan-European Bern Convention, Annex II of the Convention on Migratory Species (CMS) and Annex I of the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA). It is also listed by the Helsinki Convention (HELCOM) as a species that that is threatened and/or declining in the Baltic Sea. Across the EU, 370 Natura 2000 sites have been designated for the conservation of this species. It is included on the list of priority EU species that can benefit from a higher EU co-funding rate (up to 75%) under the LIFE Programme, although to date (June 2024) the LIFE project database lists only two projects that have taken practical conservation measures for this species. Some habitats along flyway routes are protected. Active management is also underway at some Australian sites to combat cord grass invasion, as well as protective measures implemented to reduce disturbance at roost sites (Clemens et al. 2021). The Australasian Wader Studies Group, along with BirdLife Australia's Shorebirds 2020 Project and committed volunteers continue to monitor migratory shorebirds within the East Asian-Australasian Flyway (Vine and Maurer 2016). China is investing hundreds of millions of dollars to clear tidal mudflats of Spartina cordgrass, with the aim of eliminating 90% of it by 2025; locally, this has already been successful, for example at Chongming Dongtan National Nature Reserve (Stokstad 2023). The governments of China and South Korea have halted new projects that require or depend upon land reclamation, and across the Korean Peninsula the number of coastal wetlands has increased; moreover in China and South Korea, key areas for migratory shorebirds (including A. interpres) have been identified and prioritised by government and two World Heritage nominations have been made on these grounds (IUCN 2023). Although data on scale or impact are sparse, IUCN (2023) consider that "support for coastal wetland conservation and wise-use appears to have increased over the last decade". There has been a substantial increase in the number of volunteer groups and NGOs helping to monitor the migrations of shorebirds and other waterbirds, as well as increased media coverage and special events, demonstrating enhanced awareness among coastal communities (see also EAAFP 2016). North Korea became a Party to the Ramsar Convention and joined the EAAF Partnership in 2018. In 2021, the 'Regional Flyway Initiative' (RFI) was set up by the Asian Development Bank, with technical support from BirdLife International, with the aim of protecting and restoring priority wetland ecosystems and the associated ecosystem services they provide in the East-Asian Australasian Flyway (EAAF), the most threatened flyway globally. The Initiative is slated for implementation in 10 East, South and South-East Asian countries: Mongolia, China, Bangladesh, Viet Nam, Cambodia, Lao PDR, Philippines, Thailand, Malaysia and Indonesia, all of which are used by A. interpres on northbound and southbound migrations between breeding and wintering areas, and many also for wintering. The RFI will mobilise large-scale financing to support the protection, sustainable management and restoration of at least 50 priority wetlands across ten Asian countries, with an initial financing commitment of $3 billion from the ADB (BirdLife International 2022). Over time, the RFI aims to enhance and expand the existing efforts in conserving and managing priority wetlands identified on the basis of supporting globally significant congregations of migratory waterbirds, and leverage on collaborative opportunities with stakeholders including national governments, civil society organizations, communities, regional organisations like the East Asian-Australasian Flyway Partnership. A large portion of this species' breeding population is covered by PRISM surveys in North America, enabling regular monitoring.
Conservation Actions Proposed
Ensure population monitoring continues throughout and its range, and preferably expand it to other regions (particularly in East Asia and wintering grounds in Africa where data coverage is currently patchy). In the East Asian-Australasian Flyway, the main action needed for this is the amelioration of threats on its migration. China needs to implement its plan to eliminate 90+% of Spartina cordgrass to prevent further loss of feeding habitat (much has already been lost to land reclamation; IUCN 2023). The discharge of toxic pollutants into coastal wetlands (especially where there are large shorebird congregations) needs to be controlled. Further degradation of mudflats needs to be stopped, including monitoring and preventing detrimental release of riverine sediments and responsible planning of offshore windfarms. Tools are available, such as AviStep (https://avistep.birdlife.org/) to ensure sustainable building of renewable energy infrastructure. Many of these threats, particularly development of coastal wetlands, apply also to the Arabian Peninsula where there is a need for sensible policy-making and implementation to reduce illegal killing and habitat loss (Brochet et al. 2016, de Fouw et al. 2018).
Text account compilers
Berryman, A.
Contributors
Panjabi, A., Robertson, H.A., Larsson, K., Solovyeva, D., Lehikoinen, A. & Lanctot, R.
Recommended citation
BirdLife International (2024) Species factsheet: Ruddy Turnstone Arenaria interpres. Downloaded from
https://datazone.birdlife.org/species/factsheet/ruddy-turnstone-arenaria-interpres on 25/11/2024.
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 25/11/2024.