(Prepared by the Australian Government) Summary:
The Far Eastern Curlew is an endangered migratory shorebird which is included in Appendix I and II of CMS. Resolution 11.14 on a Programme of Work on Migratory Birds and Flyways recommends the development, adoption and implementation of an Action Plan for this species.
A task force established under the East Asian – Australasian Flyway Partnership (EAAFP) in 2015 prepared the Action Plan in consultation with Range States, EAAFP Partners, non-government organizations and the research community. The Action Plan was approved by the EAAFP at its meeting of partners held in Singapore in January 2017.
The Action Plan identifies key threats and prioritizes actions required to improve the conservation status of the Far Eastern Curlew throughout its range. The Action Plan is submitted to COP12 for adoption with a view to promote immediate implementation. Implementation of the Action Plan will contribute to targets 8, 9 and 10 of the Strategic Plan for Migratory Species 2015-2023.
ACTION PLAN FOR FAR EASTERN CURLEW Background
The Far Eastern Curlew (Numenius madagascariensis) was listed as vulnerable on the IUCN Red List in 2010 and uplisted to endangered in 2015. The species was listed on the Convention on Migratory Species (CMS) Appendix II in 1994 and Appendix I in 2011. The species was designated for Concerted and Cooperative Actions under CMS in 2014. There are currently no international instruments that address conservation issues across the entire range of the species.
Resolution 11.14 on the Programme of Work on Migratory Birds and Flyways recommends the development, adoption and implementation of a Species Action Plan (SAP) for the Far Eastern Curlew in East Asia – Australasia, in cooperation with the East Asian-Australasian Flyway Partnership (EAAFP).
In 2015 at the 8th Meeting of the Partners of the EAAFP, Australia proposed the establishment of the Far Eastern Curlew Task Force. The proposal was unanimously endorsed and Australia was elected Chair.
The primary purpose of the Task Force was to draft and seek Partnership endorsement of the International Single Species Action Plan for the Far Eastern Curlew as the issues facing the species are well suited to the development of targeted conservation actions.
The Far Eastern Curlew is endemic to the East Asian – Australasian Flyway and is one of the largest migratory shorebirds in the world. The species breeds in the Russian Federation and China and migrates to the Philippines, Thailand, Palau, Malaysia, Indonesia, Papua New Guinea, Australia and New Zealand for the non-breeding period.
Evidence from Australia indicates a severe population decline of 81.4 per cent over 30 years or three generations (5.8 per cent per year). In large part, the observed decline in Far Eastern Curlew numbers stems from ongoing loss of intertidal mudflat habitat at key migration staging sites in the Yellow Sea. If habitat loss and degradation continue, it is expected that the species will continue to decline.
The Far Eastern Curlew Task Force, in cooperation with the EAAFP Secretariat, prepared a draft Single Species Action Plan which was sent to all Range States, relevant CMS Parties, EAAFP Partners and the Chairs of relevant EAAFP Working Groups and Task Forces on 5 August 2015. Further targeted consultation occurred on 17 December 2015 with Range States, non-government organizations and researchers. Written consultation with relevant CMS Secretariat staff and COP-Appointed Councillors was undertaken in 2015 and 2016. All comments received were considered and the draft action plan was amended accordingly.
The final draft of the Single Species Action Plan was again circulated for comment on 1 April 2016 to all EAAFP Partners. Comments were incorporated as appropriate, and the draft Action Plan was sent to the EAAFP Secretariat for final consideration.
Discussion and analysis
The Action Plan was presented to the 9th Meeting of Partners to the EAAFP held in Singapore in January 2017. All substantive comments made during plenary were incorporated as appropriate. The Action Plan was unanimously approved by EAAFP Partners.
In order to effectively monitor and report on the implementation of the Action Plan, the Far Eastern Curlew Task Force will be maintained through the EAAFP.
The Action Plan is being submitted to COP12 for adoption with the view of promoting immediate implementation.
The Action Plan is appended at Annex 1. Consistent with CMS policy concerning language versions of Species Action Plans, the document is produced only in English as its geographic scope does not include any French or Spanish-speaking country.
The Conference of the Parties is recommended to:
adopt the Action Plan contained in Annex 1 through draft Resolution 12.XX on species action plans for birds contained in document UNEP/CMS/COP12/Doc.24.1.11.
ANNEX 1 INTERNATIONAL SINGLE SPECIES ACTION PLAN FOR THE CONSERVATION OF THE FAR EASTERN CURLEW (Numenius madagascariensis)
The Far Eastern Curlew (Numenius madagascariensis) is the largest shorebird in the world and is endemic to the East Asian – Australasian Flyway. It breeds in eastern Russia and north-eastern China and travels through Mongolia, Japan, the Democratic People’s Republic of Korea, the Republic of Korea, China, Vietnam, Thailand and Malaysia to its non-breeding grounds. About 25 per cent of the population is thought to spend the non-breeding season in the Philippines, Indonesia and Papua New Guinea but most (estimated at 26,000 individuals) spend the non-breeding season in Australia. Evidence from Australia suggests that Far Eastern Curlews have declined by an estimated 81 per cent over 30 years and the species is listed as ‘Endangered’ on the IUCN Red List.
The greatest threat to the survival of the Far Eastern Curlew is the ongoing destruction of tidal mudflats that it utilizes on migration, especially in China, Republic of Korea and South-East Asia. In addition, hunting in some parts of its range is considered a serious threat. Other issues include human disturbance, pollution, overharvesting of potential prey animals, the effects of drought and overgrazing and climate change on habitats.
The goal of this action plan is to return the Far Eastern Curlew to a positive population growth rate for at least three generations. Essential actions to achieve this are to:
Identify, protect and manage remaining sites used by the species during its annual cycle
Reduce or eliminate illegal harvesting and incidental bycatch
Determine key demographic parameters to support population modelling
Constitute a Far Eastern Curlew Task Force and keep it functioning until the goal is achieved.
All Range States must act quickly to halt the Far Eastern Curlew’s imminent extinction. All threats must be minimized or preferably eliminated within the next decade. International and regional cooperation is essential to prevent extinction of this migratory shorebird. The East Asian – Australasian Flyway Partnership and the Convention on the Conservation of Migratory Species of Wild Animals (CMS) and other multilateral and bilateral agreements provide the frameworks necessary to ensure meaningful conservation efforts and their coordination across the region.
The Far Eastern Curlew Task Force would like to thank all those that have contributed to the development of this Action Plan. We particularly thank Judit Szabo (EAAFP Secretariat), Borja Heredia (CMS), Stephen Garnett (CMS/Charles Darwin University), Lew Young (Ramsar), Kaori Tsujita (Ministry of Environment Japan), How Choon Beng (Sungei Buloh Wetland Reserve, Singapore), Chang Hea Sook (Ministry of Environment Korea), Richard Lanctot (US Fish and Wildlife Service, Chair of the EAAFP Shorebird Working Group), Anson Tagtag (Department of Environment and Natural Resources, Philippines), Bruce McKinlay (Department of Conservation, New Zealand), Narelle Montgomery (Department of the Environment and Energy, Australia), Steve Rusbridge (Rio Tinto), Samantha Vine (Head of Conservation, BirdLife Australia), Connie Warren (BirdLife Australia), Yvonne Verkuil (Chair, International Wader Study Group), Doug Watkins (Chair, Australasian Wader Studies Group), Jon Coleman (Chair, Queensland Wader Studies Group), David Lawrie (Pukorokoro Miranda Naturalists Trust), Evgeny Syroechkovskiy (Russian Federation), Pavel Tomkovich (Moscow State University), Yuri Gerasimov (Russia Academy of Science), Yusuke Sawa (BirdLife International – Tokyo), Ju Yung Ki (Chonbuk National University), Sim Lee Kheng (Sarawak Forestry Corporation), Nial Moores (Birds Korea), Alexey Antonov, Taej Mundkur (Wetlands International), Nicola Crockford (RSPB), Daniel Brown (RSPB), Mike Crosby (BirdLife International), David Melville (Global Flyway Network), Eduardo Gallo Cajiao (University of Queensland), Richard Fuller (University of Queensland), Micha Jackson (University of Queensland), Robert Clemens (University of Queensland), Jimmy Choi (University of Queensland), Peter Dann, Danny Rogers, Glenn McKinlay, Yeap Chin Aik, Young-Min Moon, Vivian Fu, S. Gombobaatar (University of Mongolia) and Zhijun Ma (Fudan University). This Action Plan was made possible by funding from the Australian Government and the East Asian – Australasian Flyway Partnership.
The Far Eastern Curlew is the largest shorebird in the world. It is endemic to the East Asian-Australasian Flyway (EAAF), breeding in the Russian Federation and China and migrating as far as Australia and New Zealand. Declining numbers at the species’ staging and non-breeding sites prompted the IUCN Red List to recognise Far Eastern Curlew as ‘Endangered’ in 2015 (BirdLife International 2015a). In Australia, the Far Eastern Curlew has declined by 81 per cent over 30 years (equal to three generations) (Studds et al. in press) and the species is now listed as ‘Critically Endangered’ under Australia’s national environmental law (Australian Government 2015a). If the main threats continue, further declines leading to extinction is expected.
Acknowledging the severe decline of Far Eastern Curlew, the Australian Government initiated the development of this Action Plan under the auspices of the East Asian – Australasian Flyway Partnership. The Partnership and the CMS have endorsed similar Action Plans in the flyway including Action Plans for the Siberian Crane Leucogeranus leucogeranus (Ilyashenko et al. 2008), Black-faced Spoonbill Platalea minor (Chan et al., 2010), Spoon-billed Sandpiper Eurynorhynchus pygmaeus (Zöckler et al. 2010) and the Chinese Crested Tern Sterna bernsteini (Chan et al. 2010). All of these Action Plans are being successfully implemented and serve as models for this one.
This Action Plan addresses the issues at important sites along the flyway, ranging from the breeding grounds, stop-over (or staging) and non-breeding sites. To be successful, meaningful international cooperation will be required from all Range States. The mechanism of an international single species action plan has been proven to be effective in improving and coordinating conservation efforts (Boersma et al. 2001). It is the aim of this document to provide a summary of information on the status, threats, and current levels of protection in each Range State and to develop a plan of action. The Action Plan is coordinated by the Far Eastern Curlew Task Force established under the auspices of the East Asian-Australasian Flyway Partnership (EAAFP) and is designed to be implemented by governments and non-government bodies.
This Single Species Action Plan provides an important tool for promoting and coordinating conservation at an international, national and regional level. The Action Plan provides guidance for EAAFP Partners, CMS Parties, Range States, conservationists, researchers and habitat managers over the next decade, while also providing a model for further advancing migratory bird conservation throughout the flyway. The Action Plan outlines an internationally agreed list of activities necessary along the flyway, to improve the understanding of the species’ status, to halt its decline and support its long-term survival.
2. Biological assessment
Species: Numenius madagascariensis
Common names: Australian or sea curlew, Eastern Curlew, curlew, Courlis de Sibérie, Zarapito siberiano, Allak-kkorimadoyo, Isabellbrachvogel, Burung Gajahan Timur, Gajahan Timur, Gegajahan paruh besar, Gegajahan timur, Burung Kedidi Kendi Timur, Burung Kedidi Timur, Burung Kendi Timur, Kedidi Timor, Kendi Timur, นกอีก๋อยตะโพกสีน้ำตาล,, Chim Choắt mỏ cong hông nâu, Choắt mỏ cong hông nâu, 大喽儿, 大杓鹬, 紅腰杓鷸, 红腰杓鹬, 黦鷸, Дальневосточный, Дальневосточный кроншеп, Дальневосточный кроншнеп, кроншнеп, Кроншнеп дальневосточный, 알락꼬리마도요, ホウロクシギ, 焙烙鴫, 焙烙鷸, Мадагаскар тутгалжин, ᠮᠠᠳᠠᠭᠠᠰᠺᠠᠷᠲᠣᠲᠣᠭᠣᠯᠵᠢᠨ, ᠮᠠᠳᠠᠭᠠᠰᠺᠠᠷᠲᠣᠲᠣᠭᠣᠯᠵᠢᠨ, Мадагаскар тутгалжин,
Accepted as Far Eastern Curlew Numenius madagascariensis Linnaeus, 1766 (BirdLife International 2015b).
Monotypic, no subspecies are recognized (del Hoyo and Collar 2014). Taxonomic uniqueness: medium (22 genera/family, 8 species/genus, 1 subspecies/species; Garnett et al. 2011). Preliminary research by Q.Q. Bai (unpublished data) on Far Eastern Curlews in Liaoning Province, China has suggested the presence of two populations with different moulting strategies on southward migration. One of these populations is thought to spend the non-breeding season in Australia, but the breeding and non-breeding distribution of the other potential population are currently unknown.
2.2 Global Distribution
The Far Eastern Curlew is endemic to the East Asian – Australasian Flyway. Within the Russian Federation the Far Eastern Curlew breeds in Siberia and Far Eastern Russia, specifically in Transbaikalia, Magadan Region, northern and southern Ussuriland, Iman River, scattered through south, west and north Kamchatka, lower and middle Amur River basin, Lena River basin, between 110° E and 130° E up to 65° N, and on the Upper Yana River, at 66° N (Higgins & Davies 1996). Although reported to breed in Mongolia (e.g. del Hoyo et al. 1996) there are no records, the species only occurring as a migrant (Gombobaatar & Monks 2011; S. Gombobaatar in litt. 25 November 2016; Axel Braunlich in litt. 24 November 2016). However, it is reported to breed in north-eastern China(Nei Mongol, Heilongjiang and Jilin) (Zhao 1988; Ma 1992; Wang et al. 2006; Xu 2007) with nests, eggs and young recorded in Heilongjiang in 1985 (Ma 1992) and three birds breeding/attempting to breed in 2011 (Gosbell et al. 2012).
The Far Eastern Curlew is a migrant in Mongolia (Gombobaatar & Monks 2011), Japan (The Ornithological Society of Japan 2012), Democratic People’s Republic of Korea (Tomek 1999), Republic of Korea (Moores 2006), and China (Wang et al. 2006). Very small numbers are recorded moving through Thailand and PeninsularMalaysia in the non-breeding season (Melville 1982; Wells 1999; Round 2006). It is a rare passage migrant in Singapore (Lim 2015), and there is one record from Vietnam (Eames 1997).
During the non-breeding season very small numbers occur in the southern Republic of Korea, Japan and China (Li & Mundkur 2004). About 25 per cent of the population is thought to spend the non-breeding season in Borneo, the Philippines, Indonesia and Papua New Guinea (although Bheeler & Pratt 2016 only record it on passage) but most of the population (estimated in 2008 at 73 per cent) spend the non-breeding season in Australia (Bamford et al. 2008). Far Eastern Curlews are regular non-breeding visitors to New Zealand in very small numbers (Southey 2009), and occur very rarely on Kermadec Island and the Chatham Islands (Checklist Committee (OSNZ) 2010).
Small numbers of Far Eastern Curlews spend the non-breeding season in Palau (McKinlay 2016). It is recorded as a very rare migrant in the Mariana Islands (Stinson et al. 1997), and vagrant elsewhere in Micronesia (Yap, Truk/Chuuk, and Guam) (Pratt et al. 1987; Wiles et al.2000; Wiles 2005), and on Savaii, Samoa (Pratt et al. 1987). There are occasional records from Fiji (Skinner 1983).
It is a vagrant in the Aleutian and Pribilof Islands, Alaska, USA (Thompson & DeLong 1969; Gibson & Byrd 2007), with one record in Canada (Kragh et al. 1986). Single records from Diego Garcia, British Indian Ocean Territory (Carr 2015), Bangladesh (Thompson et al. 1993) and Afghanistan (Reeb 1977) although Rasmussen & Anderton (2005) consider the latter two records unconfirmed.
During the boreal summer considerable numbers of non-breeding, presumed immature, Far Eastern Curlews occur in the northern Yellow Sea and Bohai (Q.Q. Bai unpublished; N. Moores unpublished). Barter (2002) reported large numbers of ‘immature’ birds at Yancheng during the boreal summer, but it is unclear whether they still occur at this site as extensive invasion of the tidal flats by smooth cord-grass Spartina alterniflora has greatly reduced the value of this site to shorebirds (Melville et al. 2016).
Within Australia, the primary non-breeding Range State, the Far Eastern Curlew has a mostly coastal distribution; they are rarely recorded inland. The species is found in all states, particularly the north, east, and south-east regions including Tasmania. Their distribution is continuous from Barrow Island and Dampier Archipelago, Western Australia, through the Kimberley Division and along Northern Territory, Queensland, and New South Wales coasts and the islands of Torres Strait. They occur patchily elsewhere.
Figure 1. Distribution of Far Eastern Curlew (Yellow = Breeding, Pink = Passage and Blue = Non-breeding. Source: BirdLife International 2015b)
2.3 Population size and trend
The global population estimate in 2008 was 38,000 individuals (Bamford et al 2008), but documented declines in Australia (Garnett et al. 2011) resulted in a revised estimate of 32,000 (Wetlands International 2012). Applying a different approach using count data and extrapolation to non-counted habitat resulted in the most recent global population estimate of 35,000 (Hanson et al 2016). The majority of the estimated population – 26,000 to 28,000 birds – occurs in the non-breeding season in Australia (Bamford et al. 2008; Hansen et al. 2016), with an additional 5,000 in Indonesia, 3,000 in China and 2,000 in Papua New Guinea (Australian Government 2015a).
Barter (2002) estimated that 31,500 birds (83 per cent of the then estimated world population) stage in the Yellow Sea on northward migration. The species is affected by habitat loss and degradation of intertidal habitat caused by reclamation, major infrastructural development and pollution. There was a 99 per cent decline of Far Eastern Curlew staging at Saemangeum, Republic of Korea during northward migration between 2006 and 2014, with evidence of only limited displacement to adjacent sites following seawall closure there in 2006 (Moores et al. 2016). Numbers recorded at the Nakdong Estuary have also declined markedly following a series of development projects including construction of an estuarine barrage in the late 1980s, and reclamation projects and bridge-building in the 2000s, with a maximum count of 635 during southward migration in 1983 but of only 193 during southward migration in 2005 and 46 in 2014 (Wetlands and Birds Korea 2005; Shorebird Network Korea 2015). There were no clear trends in Japan between 1978 and 2008 (Amano et al. 2010), but this region lies outside the main migration route of the Far Eastern Curlew, especially during northward migration. There has been a fairly steady decline in Far Eastern Curlew numbers in New Zealand since the early 1980s, with an apparent acceleration in the decline since 2004; formerly about 20 birds wintered there (Higgins and Davies 1996) but now fewer do so (Southey 2009). Since 2008 fewer than ten have visited each summer. A few non-breeders stay in New Zealand over the southern winter (Riegen 2013).
In Micronesia, Baker (1951) noted the Far Eastern Curlew as ‘a regular visitor to western Micronesia, especially Palau Islands’, and Wiles et al. (2000) noted: This species was once apparently a regular migrant to western Micronesia but has become much rarer throughout its range in recent decades. Only a handful of reports have been published for the region since 1945’. McKinlay (2016) regularly recorded small numbers on Palau, but noted ‘The species was once more common, but sightings elsewhere are now rare’. In Australia, numbers appear to have declined on Eighty-mile Beach, Western Australia by c.40 per cent between 2000 and 2008, whereas numbers at Roebuck Bay, Western Australia have remained relatively stable (Rogers et al., 2009). At Moreton Bay, Queensland they declined by c. 2.4 per cent per year between 1992 and 2008 (Wilson et al. 2011), across the whole of Queensland they declined by c. 4.1 per cent per year between 1992 and 2008 (Fuller et al., 2009), in Victoria by 2.2 per cent per year between 1982 and 2011 (Minton et al., 2012) and in Tasmania by 80 per cent between the 1950s and 2000 (Reid & Park 2003) and by 40 per cent across 49 Australian sites between 1983 and 2007 (BirdLife Australia in litt. 2011). An observation of over 2000 Far Eastern Curlews at Mud Islands, Port Phillip Bay, Victoria in 1953 (Tarr and Launder 1954), compared to current counts of fewer than 50 birds in Port Phillip Bay, suggests that population declines in the Far Eastern Curlew may have begun well before regular shorebird counts were initiated in Australia. Far Eastern Curlews have declined in south and east Australia more rapidly than those in the west (Clemens et al. 2016).
An unpublished assessment of the numbers of Far Eastern Curlews at roost sites in Tasmania showed decreases of between 55 per cent and 93 per cent, depending on site (cited in Australian Government 2015a). In the southeast, the decrease was 90 per cent for the period 1964/65 – 2010/11, and in the north, the decrease was 93 per cent between 1973/74 and 2010/11 (cited in Australian Government 2015a). At both of these sites, and at other roost sites in Tasmania, the decreases have continued, with fewer birds seen in 2014 (cited in Australian Government 2015a).
In 2015 this species was listed as ‘endangered’ in the IUCN Red List owing to the past, recent and ongoing rapid population decline of 50-79 per cent in three generations (30 years), based on survey data and habitat loss. Time series data from directly observed summer counts at a large number of sites across Australia indicated a severe population decline of 66.8 per cent over 20 years (5.8 per cent per year; Australian Government 2015a), and 81.4 per cent over 30 years which for this species is equal to three generations (Garnett et al. 2011; Australian Government 2015a).
2.4 Habitat requirements
2.4.1 Breeding habitat
Far Eastern Curlews nest during the boreal summer, from early May to late June, often in small congregations of two to three pairs. Pairs breed in open mossy or transitional bogs, moss-lichen bogs and wet meadows, on swampy shores of small lakes and tundra. Nests are positioned on small mounds in swampy ground, often near where wild berries are growing. The nest is lined with dry grass and twigs. Clutches usually contain four eggs. Juveniles may delay breeding until three or four years of age (del Hoyo et al. 1996; Ueta & Antonov 2000; Antonov 2010).
2.4.2 Non-breeding habitat
During the non-breeding season the Far Eastern Curlew is almost entirely dependent on freshwater lake shores, various wetlands, and coastal intertidal habitats. It is most commonly associated with sheltered coasts, especially estuaries, bays, harbours, inlets and coastal lagoons, with large intertidal mudflats or sandflats, often with beds of seagrass (Zosteraceae). Occasionally, the species occurs on ocean beaches (often near estuaries), and coral reefs, rock platforms, or rocky islets. The birds are often recorded among saltmarsh and on mudflats fringed by mangroves, and sometimes use the mangroves. The birds are also found in saltworks and sewage farms (Higgins & Davies, 1996).
2.4.3 Feeding habitat
The Far Eastern Curlew mainly forages during the non-breeding season on sheltered intertidal sandflats or mudflats, that are open and without vegetation or covered with seagrass. Far Eastern Curlew often forage near mangroves, on saltflats and in saltmarsh, rockpools and among rubble on coral reefs, and on ocean beaches near the tideline, however, they have a preference for soft substrates containing little or no hard material (e.g. rock, shell grit, coral, debris) that provide better access to their prey (Finn et al., 2007, 2008). The birds are rarely seen on near-coastal lakes or in grassy areas (Higgins & Davies, 1996). Inland in East Asia individuals occur in open river valley, marshes and different wetlands with tall vegetation and fresh water lake shores and small islands (Gombobaatar et al. 2011), and saltponds (D.S. Melville unpublished).
2.4.4 Roosting habitat
The Far Eastern Curlew roosts during high tide periods on sandy spits and islets, especially on dry beach sand near the high-water mark, and among coastal vegetation including low saltmarsh or mangroves. It occasionally roosts on reef-flats, in the shallow water of lagoons, aquaculture ponds and other near-coastal wetlands. Far Eastern Curlews are also recorded roosting in trees and on the upright stakes of oyster-racks (Higgins & Davies 1996). At Roebuck Bay, Western Australia, birds have been recorded flying from their feeding areas on the tidal flats to roost 5 km inland on a claypan (Collins et al. 2001). Within Moreton Bay, Queensland, Australia, the distance over which Far Eastern Curlew typically travel between feeding and roosting habitat is 5-10 km, with high mobility between alternative roosts and/or feeding grounds occurring at or below this distance (Finn et al. 2002). In some conditions, shorebirds may choose roost sites where a damp substrate lowers the local temperature. This may have important conservation implications where these sites are heavily disturbed beaches (Rogers, 1999). From the requirements known for roosting habitat, it may be possible to create artificial roosting sites to replace those destroyed by development (Harding et al., 1999). Far Eastern Curlews typically roost in large flocks, separate from other shorebirds (Higgins & Davies, 1996).
2.5 Migration patterns
The Far Eastern Curlew is migratory. After breeding, they move south for the austral summer.
2.5.1 Departure from breeding grounds
Far Eastern Curlews leave Kamchatka Peninsula (Eastern Russia) from mid-July (Ueta et al. 2002) to mid-September. Birds migrate through Ussuriland, Russia, from mid-July to late September, birds pass through Sakhalin, (Eastern Russia), from mid-July to late August (Higgins & Davies 1996). Fewer birds appear in continental Asia on the southern migration than on the northern migration (Dement'ev & Gladkov 1951). Far Eastern Curlews are seen in Democratic People’s Republic of Korea, Republic of Korea, Japan and China from June to November with birds seen in Thailand, the Peninsular Malaysia, Singapore, the Philippines, and Borneo (Indonesia, Brunei and Malaysia), from August to December (White & Bruce 1986; Dickson et al. 1991; Higgins & Davies 1996; Mann 2008; Moon et al. 2013; Choi et al. 2016) likely to be a mix of passage migrants and overwintering individuals. Migrating individuals are often seen with Eurasian Curlews (Numenius arquata) by late July to early September in Mongolia (Gombobaatar et al. 2011).
The birds arrive in north-west and eastern Australia as early as July (Lane 1987). In north-west Australia, the peak arrival time is in mid-August (Minton & Watkins 1993). There is an onward movement from north-west Australia by October (Lane 1987). Most birds arriving in eastern Australia appear to move down the coast from northern Queensland with influxes occurring on the east coast from mid-August to late December, particularly in late August (Choi et al. 2016). Counts suggest there is a general southward movement until mid-February (Alcorn 1988). Records from Toowoomba, Broken Hill and the Murray-Darling region in August and September suggest that some birds move overland (Higgins & Davies 1996) and the timing of arrival along the east and south-east Australian coasts suggests some fly directly to these areas (Alcorn 1988). In Victoria, most birds arrive in November, with small numbers moving west along the coast as early as August (Lane 1987). In southern Tasmania, most arrive in late August to early October, with a few continuing to arrive until December (Higgins & Davies 1996). When Far Eastern Curlews first arrive in Tasmania they are found at many localities before congregating at Ralphs Bay or Sorell (Thomas 1968).
Far Eastern Curlews arrive in New Zealand from the second week of August to mid-November with a median date of mid-October (Higgins & Davies 1996). Although in recent years, very few birds have been seen.
2.5.2 Non-breeding season
During the non-breeding season small numbers of Far Eastern Curlew occur in coastal southern Republic of Korea, Japan, and China (Li & Mundkur 2004). Unquantified numbers occur in Indonesia, Papua New Guinea, Borneo, and the Philippines (Higgins & Davies 1996.Li et al. (2006) recorded at total of 14 Far Eastern Curlews in the whole of Malaysia in the period November 2004 to February 2005. In Sabah, Malaysia Li et al. (2006) recorded 230 Far Eastern Curlews on the Bako-Semera coastline in April 2005, when it was considered that they may have been migrating.
The majority of the Far Eastern Curlew population is found in Australia during the non-breeding season (Bamford et al. 2008), mostly at a few sites on the east coast and in north-western Australia (Lane 1987). Population numbers are stable at most sites in November or between December-February, suggesting little movement during this period (Lane 1987; Alcorn 1988).
Analysis of biometrics of Far Eastern Curlew by Nebel et al. (2013) showed that they have a strongly skewed sex ratio in south-eastern Australia; only 35.3 per cent of adult Far Eastern Curlew captured were male (n = 383 birds). In contrast, 54.3 per cent of adult Far Eastern Curlew captured in north-western Australia were male (n = 102). These data suggest that male and female Far Eastern Curlew have preferences for different non-breeding areas, with females migrating further south.
2.5.3 Return to breeding grounds
Most Far Eastern Curlews leave Australia between late February and March-April (Higgins & Davies 1996; Driscoll & Ueta 2002). The birds depart New Zealand from mid-March to mid-May (Higgins & Davies 1996) and peak in abundance at some sites in the Republic of Korea in early to mid-April (Moores 2012), and in mid-April in Hong Kong (Carey et al. 2001). The species has been recorded on passage elsewhere mostly between March and May, arriving at Kamchatka, Russia, during May (Higgins & Davies 1996).
Like many other large shorebirds, young Far Eastern Curlew can spend their second austral winter in Australia, and some may also spend their third winter in Australia before undertaking their first northward migration to the breeding grounds (Wilson, 2000). The numbers of birds that remain on the non-breeding grounds during the austral winter are around 25 per cent of the peak austral summer numbers (Finn et al. 2001). Large numbers (locally tens or hundreds) apparently remain throughout the boreal summer at some coastal sites in the Republic of Korea (especially in Gyeonggi Bay) (N. Moores pers comm.), and in Liaoning, China (Q.Q. Bai unpublished). More research is required to determine whether these are immature birds and/or failed breeders.
2.6 Diet and foraging behaviour
The Far Eastern Curlew’s diet on the breeding grounds includes insects, such as larvae of beetles and flies, and amphipods. During August-September, prior to southward migration, berries are also consumed (Gerasimov et al. 1997). During the non-breeding season, Far Eastern Curlew mainly eats crustaceans (including crabs, shrimps and prawns), but small molluscs, as well as some insects are also taken (Dann 2005; Finn et al., 2008; Dann 2014; Zharikov & Skilleter 2003, 2004a, 2004b). In the Republic of Korea Far Eastern Curlews principally feed on Macrophthalmus crabs (Piersma 1985; Yi et al. 1994).
In Roebuck Bay, Western Australia, the birds feed mainly on large crabs, but will also catch mantis shrimps and chase mudskippers (Rogers, 1999). In southern Australia, Far Eastern Curlews feed on a variety of crabs and shrimps (Dann 2014). Far Eastern Curlews find the burrows of prey by sight during the day or in bright moonlight, but also locate prey by touch. The sexual differences in bill length lead to corresponding differences in diet and behaviour (Higgins & Davies 1996; Dann 2005, 2014). Male and female Far Eastern Curlews use intertidal habitat area differently, with females using more sandy areas and males use more muddy areas (Dann 2014).
The birds are both diurnal and nocturnal with feeding and roosting cycles determined by the tides. Far Eastern Curlews usually feed alone or in loose flocks. Occasionally, this species is seen in large feeding flocks of hundreds (Higgins & Davies 1996).
2.7 Important Sites
In this Action Plan ‘important sites’ are defined based on a threshold of the Far Eastern Curlew global population. Here we consider sites that contain ≥1 per cent of the population as internationally important and requiring special protective measures (this being equivalent to Criterion 6 for identifying wetlands of international importance under the Ramsar Convention). In some countries, like Australia, ‘nationally important sites’ are defined as those areas that contain ≥0.1 per cent of the population (Australian Government 2015c).
Internationally, the Yellow Sea region is extremely important as stopover habitat for Far Eastern Curlews. It supports about 80 per cent of the estimated flyway population on the northward migration (most of the remaining population apparently staying on the non-breeding grounds). Fewer are counted in the region during the southward migration, but this may be an artefact of their staggered migration.
Relatively few Far Eastern Curlews pass through Japan (Brazil 1991). Thirteen sites of international importance were identified in the Yellow Sea (six in China, six in Republic of Korea and one in Democratic People’s Republic of Korea) (Barter 2002; Bamford et al. 2008). Twelve sites were considered important during the northward migration and seven during the southward migration, with six sites (Dong Sha, Shuangtaizihekou National Nature Reserve, Ganghwa Do, Yeong Jong Do, Mangyeung Gang Hagu and Dongjin Gang Hagu) important during both (Barter 2002; Bamford et al. 2008). It is important to note that despite being recognized as internationally important, habitat in some of these sites has been destroyed since the Barter (2002) surveys. For example, Mangyeung Gang Hagu and Dongjin Gang Hagu in the Republic of Korea (both part of Saemangeum impounded since 2006) are no longer considered important sites for Far Eastern Curlew (Moores et al. 2016). Ganghwa Do (Island), Yeongjong Do (Island), Janghang Coast and Yubu Do (Island) in the Geum Estuary and Namyang Bay now account for nearly 90 per cent of the population in the Republic of Korea. In China, Bai et al. (2015) identified seven internationally important sites for Far Eastern Curlew in the Yellow Sea region. During northward migration, Yalu Jiang estuarine wetland, Yellow River Delta and Shuangtaizihekou National Nature Reserve are utilized by large numbers of Far Eastern Curlew, particularly Yalu Jiang with 4,840 individuals recorded in April 2011. During southward migration, Yalu Jiang estuarine wetland, Tianjin coast, Zhuanghe Bay, Shuangtaizihekou National Nature Reserve, Cangzhou coast, Rudong coast, and the Yellow River Delta are considered internationally important. Again, Yalu Jiang is the most important site with 5,289 individuals recorded in July 2011(Bai et al. 2015).
Recent surveys in the Democratic People’s Republic of Korea (Riegen et al. 2016) found internationally important numbers of Far Eastern Curlews at three sites: Ilhae-ri/Sema-ri, Mundok and Undok-ri.
Outside the Yellow Sea, the Moroshechnaya River Estuary in Far East Russia is an internationally important site for Far Eastern Curlews during the southward migration. In Indonesia, the Banyuasin Delta in Sumatra is important during southward migration (Bamford et al. 2008) and in January (Li et al. 2009), while Pesisir Timur Pantai Sumatera Utara is internationally important in January (Conklin et al. 2014). In Sarawak, Malaysia, Pulau Bruit is internationally important for Far Eastern Curlews during northward migration (Mann 2008), and Sejinkat Ashponds is an internationally important non-breeding site (Conklin et al. 2014). There are few records from Brunei Darussalam (Moore undated). Bamford et al. (2008) identified the Kikori Delta as an important site in Papua New Guinea and Conklin et al. (2014) added the Bensbach-Bula coast.
During the non-breeding season, Australia is the most important country in the EAAF accounting for at least 73 per cent of the population (Bamford et al. 2008). At least 19 sites have been identified as internationally important for the Far Eastern Curlew (Bamford et al. 2008). Most are located along the north and east coasts of Australia and four sites are located in the southern state of Victoria. Both Moreton Bay in Queensland and Buckingham Bay in the Northern Territory have been identified as internationally important austral wintering sites for the Far Eastern Curlew, probably containing young birds that have not made the migration north.
Many of these sites are based on old count data and an outdated population level threshold (estimate 38 000; 1 per cent = 380 individuals). Recent work suggests the population estimate is no greater than 35,000 individuals (1 per cent = 350) (Hansen et al. 2016). There is an urgent need to reassess the number and location of sites of international importance based on this new population estimate.
The main threat to Far Eastern Curlew is considered to be reclamation of intertidal flats for tidal power plants and barrages, port development, industrial use, agricultural and urban expansion in the Yellow Sea where it stages on migration (Bamford et al. 2008; van de Kam et al. 2010; Murray et al. 2014; Melville et al. 2016). Other threats along their migration route include hunting, incidental capture in fishing nets, environmental pollution, invasive cordgrass Spartina, reduced river flows resulting in reduced sediment flows competition for food from humans harvesting intertidal organisms, and human disturbance (Barter 2002; Chen and Qiang 2006; Moores 2006; Melville et al. 2016). Threats in Australia, especially eastern and southern Australia, include ongoing human disturbance, habitat loss and degradation from pollution and structural modification of soft-sediment feeding flats, changes to water regimes and invasive plants (Rogers et al. 2006; Finn 2009; Garnett et al. 2011; Australian Government 2015 a,b,c).
Human disturbance can cause shorebirds to interrupt their feeding or roosting and may influence the area of otherwise suitable feeding habitat that is actually used. Far Eastern Curlews are amongst the first shorebirds to take flight when humans approach to within 30–100 metres (Taylor & Bester, 1999), 185 metres (Paton et al. 2000), or even up to 250 metres away (Peter 1990). Coastal development, port development, land reclamation, construction of barrages and stabilization of water levels can destroy feeding habitat (Close & Newman 1984; Sutherland et al. 2012; Melville et al. 2016). Pollution around settled areas may reduce the availability of food by altering prey composition and/or reducing substrate penetrability (Close & Newman 1984; Finn 2009). The species has been hunted intensively on breeding grounds and at stopover points while on migration and on the non-breeding grounds (Higgins & Davies 1996; Gerasimov et al. 1997). Illegal hunting in Russia is still occurring occasionally (Y. Gerasimov pers. comm.).
3.1 Description of key threats
3.1.1 Habitat loss
Habitat loss occurring as a result of development is the most significant threat currently affecting migratory shorebirds along the EAAF (Melville et al. 2016). Of particular concern in the EAAF is coastal development and intertidal mudflat ‘reclamation’ in the Yellow Sea region, which is bordered by China, the Democratic People’s Republic of Korea and the Republic of Korea (Murray et al. 2014; Melville et al. 2016). A migratory shorebird’s ability to complete long migration flights depends on the availability of suitable habitat at sites throughout the EAAF that provide adequate food and roosting opportunities to rebuild energy reserves (Piersma et al. 2015).The Yellow Sea region is the major staging area for several species of shorebird, including almost the entire population of the Far Eastern Curlew, which flies between Australia and the east coast of Asia on migration (Barter 2002; Bamford et al. 2008; Minton et al. 2011, 2013; Iwamura et al. 2013; Moores et al. 2016). In a recent study using historical topographical maps and remote sensing analysis, Murray et al. (2014) showed that 65 per cent of the tidal flats that existed in the Yellow Sea in the 1950s have disappeared, from a combination of coastal development and reduced sediment input to the Yellow Sea which is some areas is resulting in erosion. Losses of such magnitude are the key drivers of decreases in biodiversity and ecosystem services in the intertidal zone of the region (MacKinnon et al. 2012; Ma et al. 2014). Further reclamation projects are ongoing or are in the planning stage in the Yellow Sea region; for example, Jiangsu Province, China plans to reclaim 1,800 km2 (Zhang et al. 2011).
Overall, coastal development in east and south-east Asia is accelerating and is already at a pace which is unprecedented in other parts of the world. Examples of urban expansion in coastal areas are well known from Australia, the Republic of Korea, Japan, and Singapore and most other countries in the region. Development for industry, housing, tourist and transport infrastructure is widespread. In some coastal areas, intertidal areas are increasingly used for conversion into land for new settlements and intensive aquaculture.
Habitat loss in the breeding grounds has also occurred, for instance, in the Amur River basin, there are examples of hydroelectric scheme dams inundating nesting areas e.g. the Zea reservoir in the 1970s and further dams in the future could destroy other breeding areas (Brown et al. 2014). Studies analysing satellite images indicated a decrease of 80 per cent marshland (i.e. potential nesting ground for Far Eastern Curlew) over the last 50 years in north-east Heilongjiang Province, China (Liu et al. 2004; Liu et al. 2015). The authors’ study area overlapped with the breeding ranges identified in Far Eastern Curlew geolocator studies (Gosbell et al. 2012).
Drought and livestock overgrazing in the major migrating and stopover site in Mongolia have been leading to habitat degradation and loss (Gombobaatar et al. 2011).
3.1.2 Habitat degradation
Modification of wetland habitats can arise from a range of different activities including fishing or aquaculture, forestry and agricultural practices, mining, changes to hydrology and development near wetlands for housing or industry (Lee et al. 2006; Sutherland et al. 2012; Melville et al. 2016). Steppe fires in spring and autumn destroy their feeding habitats in Mongolia (Gombobaatar et al. 2011). Such activities may result in increased siltation, pollution, weed and pest invasion, all of which can change the ecological character of a shorebird area, potentially leading to deterioration of the quantity and quality of food and other resources available to support migratory shorebirds (Sutherland et al. 2012 and references therein; Ma et al. 2014; Murray et al. 2015; Melville et al. 2016). The notion that migratory shorebirds can continue indefinitely to move to other important habitats as their normal feeding, staging or roosting areas become unusable is erroneous. As areas become unsuitable to support migratory shorebirds, areas that remain will likely attract displaced birds, in turn creating overcrowding, competition for food, depletion of food resources, and increased risk of disease transmission. The areas identified today are likely to represent the great majority of suitable stop-over sites and are irreplaceable. They need to be protected immediately and managed appropriately to ensure the species’ survival.
Structural modification of feeding flats
Far Eastern Curlews require deep deposits of soft, penetrable sediment to realize their greatest foraging potential. Any structural modification of the Far Eastern Curlews’ soft- sediment feeding flats that reduces the substrate penetrability may inhibit successful foraging and be detrimental to them (Finn 2009). There are several causes of structural modification that may reduce the substrate penetrability of intertidal flats. Direct effects include activities such as intertidal oyster farming, the compaction of sediments by vehicles, the dumping of rubbish or debris and the artificial building up of beaches by adding foreign sediment to the intertidal zone. Indirect effects on the structure of soft-sediment intertidal zones can come from processes such as nutrient enrichment and the use of chemicals, such as the organophosphorus pesticide triazophos, to kill predators prior to spat seeding in aquaculture (Melville et al. 2016).
Intertidal oyster or mussel farming, whether bottom or suspended culture, may degrade the foraging habitat of shorebirds (Hilgerloh et al. 2001; Caldow et al. 2003; Connolly & Colwell 2005). The sediment structure may be rendered less penetrable by the presence of hard-shelled bivalves in abnormally high densities, the structures used for attaching bivalves (such as trestles) and/or the use of mechanical devices during harvest (such as dredges; Piersma et al. 2001; Connolly & Colwell 2005).
The compaction of sediments by vehicles may reduce the penetrability of the substrate and thereby inhibit burying by invertebrates and probing by shorebirds (Evans et al.1998; Moss & McPhee 2006; Schlacher et al. 2008).
Physical modifications of soft sediments that increase their coarseness or hardness such as that caused by the dumping of rubbish or debris (including dredge spoil) and even beach filling (nourishment) are highly likely to degrade feeding habitats for deep-probing shorebirds (Peterson et al. 2006). The dumping of dredge spoil may however be important in some areas above highest astronomical tide for providing suitable roosting habitat for shorebirds (Yozzo et al. 2004).
Processes that increase the available nutrients in the intertidal zone (such as sewage discharge and runoff from terrestrial soils) may lead to eutrophication and the proliferation of algal mats (Raffaelli 1999; Lopes et al. 2006). These algal mats may reduce substrate penetrability and are therefore likely to be avoided by deep-probing shorebirds, unless there is an associated increase in suitable prey at the substrate surface (Lewis & Kelly 2001).
In southern parts of the breeding range, both arable and livestock farming are increasing, and this thought to be degrading breeding habitats (Brown et al. 2014). The burning of grasslands is an important land management practice in this area. Anecdotal evidence at one breeding site suggests Far Eastern Curlew preferentially nest within recently-burned grasslands, with high nest success recorded (Antonov 2010). After nesting, chicks are frequently observed foraging in nearby swamps and sedge meadows, suggesting a mosaic of unburnt grassland, burnt grasslands and wetlands is important (Antonov 2010). However, burning can also have a devastating impact on breeding success if undertaken during the nesting period: one study to the south of the Amur region recorded 28 per cent of nests destroyed by fires (Antonov 2010). The timing of burning is therefore of critical importance. The impact of regular burning on invertebrate food resources is not well understood (Brown et al. 2014).
Of specific concern for migratory shorebirds is the introduction of exotic marine pests resulting in loss of benthic food sources at important intertidal habitat (Neira et al. 2006). Predation by invasive animals, such as cats (Felix catus) and foxes (Vulpes vulpes) in Australia has not been quantified, but anecdotal evidence suggests some individuals are taken as prey.
Invasive species are negatively affecting coastal habitats, causing local species to be displaced by species accidentally or deliberately introduced from other areas. With an increase in global shipping trade the influx of such species is increasing, especially in the coastal zone. In China smooth cordgrass Spartina alterniflora was deliberately introduced to speed accretion and by 2007 covered at least 34,451 ha of former tidal flats (Zuo et al. 2012) and has been responsible for the severe degradation of the intertidal areas at Yancheng National Nature Reserve, Jiangsu Province (Liu et al. 2016) – a site that Barter (2002) noted as internationally important for the Far Eastern Curlew.
Overharvesting of intertidal resources, including fish, crabs, molluscs, annelids, sea-cucumber, sea-urchins and seaweeds can lead to decreased productivity and changes in prey distribution and availability (MacKinnon et al. 2012). The recent industrialization of harvesting methods in China has resulted in greater harvests of intertidal flora and fauna with less manual labour required, which is impacting ecosystem processes throughout the intertidal zone (MacKinnon et al. 2012). In many important shorebirds areas, the intertidal zone is a maze of fishing platforms, traps and nets that not only add to overfishing, but prevent access to shorebird feeding areas by causing human disturbance (Melville et al. 2016).
Altered hydrological regimes
Altered hydrological regimes can directly and indirectly threaten migratory shorebird habitats. Water regulation, including extraction of surface and ground water (for example, diversions upstream for consumptive or agricultural use), can lead to significant changes to flow regime, water depth and water temperature. Reduced water flows and associated reduced sediment discharge from the Yellow and Yangtze Rivers in China are having major impacts on near coast environments (Murray et al. 2015). Changes to flows can lead to permanent inundation or drying of connected wetlands, and changes to the timing, frequency and duration of floods. These changes impact both habitat availability and type (for example, loss of access to mudflats through permanent higher water levels, or a shift from freshwater to salt-tolerant vegetation communities), and the disruption of lifecycles of plants and animals in the food chain for migratory shorebirds.
Reduced recharge of local groundwater that occurs when floodplains are inundated can change the vegetation that occurs at wetland sites, again impacting habitat and food sources.
Water regulation can alter the chemical make-up of wetlands. For example, reduced flushing flows can cause saltwater intrusion or create hyper-saline conditions. Permanent inundation behind locks and weirs can cause freshwater flooding of formerly saline wetlands, as well as pushing salt to the surface through rising groundwater.
3.1.3 Climate change
Climate change is expected to have a major impact on coastal mudflats and breeding habitat throughout the EAAF. Such changes have the potential to impact on all migratory shorebirds and their habitats by reducing the extent of coastal and inland wetlands or through a poleward shift in the range of many species (Chambers et al. 2005; Iwamura et al. 2013; Wauchope et al. 2015). Climate change projections for the EAAF suggest likely increased temperatures, rising sea levels, more frequent and/or intense extreme climate events resulting in likely species loss and habitat degradation (Chambers et al. 2005, 2011; Iwamura et al. 2013; Nicol et al. 2015).
The Far Eastern Curlew’s breeding range is in a region predicted to be one of the most heavily influenced by climate change (Wauchope et al. 2015). Rising annual and summer temperatures will change the vegetation composition making areas less suitable as breeding habitat for the species. Predictions of decreasing precipitation in both winter and spring will lead to drying breeding habitat and loss of preferred nesting habitat around swampy ground. Depending on the exact geographical location and microclimate conditions, this could mean significant changes in key breeding habitats.
3.1.4 Hunting, Poaching and Incidental Take
Hunting of migratory shorebirds in Australia and New Zealand has been prohibited for a number of decades. It is unclear if illegal hunting occurs during the annual duck hunting season in certain Australian states. Far Eastern Curlews were shot for food in Tasmania, Australia until the 1970s (Park 1983; Marchant & Higgins 1993). Hunting also appears to have decreased in the Republic of Korea, with the only reported instance being minor hunting activity in Mangyeung Gang Hagu (Barter 2002).
Investigations into shorebird hunting activities at internationally important sites in China in the early 1990s, including in the Chang Jiang Estuary, Yellow River delta and Hangzhou Bay, suggested that tens of thousands of shorebirds were being trapped annually (Tang & Wang, 1991, 1992, 1995; Barter et al. 1997; Ma et al. 1998). Of 8,828 birds caught by hunters and identified there were 62 Far Eastern Curlews (0.7%) (Tang & Wang 1995). Studies during the 2000-2001 period indicate that hunting activity had declined at Chongming Dao, China (Ma et al. 2002).
Wang et al. (1991, 1992) reported hunting activity in the Yellow River Delta, estimating that 18,000-20,000 shorebirds were caught with clap nets during northward migration in 1992 and probably a higher number during southward migration in 1991. However, no hunting was observed in the Yellow River Delta during surveys in the 1997, 1998 and 1999 northward migrations (Barter 2002). With the exception of the Chang Jiang Estuary, no hunting activity was detected in China during shorebird surveys that covered about one-third of Chinese intertidal areas between 1996 and 2001 (Barter 2002).
They have been hunted at stopover points while on migration as well as on their breeding grounds in the Russian Federation where hunting has been reported since at least the 1980s (Tomkovich 1996), and Gerasimov et al. (1997) considered hunting to be main reason for the decline in numbers in Kamchatka. More recently, hunting of Far Eastern Curlews in Russia has been recorded as part of duck hunting (Victor Degtyaryev, Igor Fefelov, pers. comm. 2014). In the Russian Federation a special hunting season for shorebirds occurs before the season for hunting ducks, mainly for Whimbrels. It has been suggested that hunters cannot correctly distinguish Far Eastern Curlews from Whimbrels, particularly considering that young Far Eastern Curlews have a shorter bill in August (E. Syroechkovskiy). There are no current data on levels of take in the breeding grounds, and “occasional” hunting remains by most as a qualitative assessment, which is insufficient to assess population-level effects.
Mist-netting of shorebirds for local consumption and to supply local food markets still occurs in a number of countries, including China, although generally not in areas where Far Eastern Curlews are concentrated (Melville et al. 2016). Incidental catch in fishnets, however, is known to kill Far Eastern Curlews in Liaoning, China (D.S. Melville unpublished). Deliberate poisoning of curlews using the organochloride pesticide hexachlorocyclohexane has also been reported in China (Melville et al. 2016). It is unclear if the Far Eastern Curlew makes up a significant proportion of the take. However, even if only small numbers are taken, the impact could be severe in the long term. Turrin & Watts (2016) were unable to estimate sustainable harvest levels for Far Eastern Curlews due to gaps in knowledge of the birds’ life history. Considering that the current level of take across the entire range of this species is unknown, it is not justified to conclude that low levels of hunting at small spatial scales have negligible deleterious population-level effects.
Illegal fishing activities using gill nets, and abandoned gill nets on shore are potential impacts on the species in Mongolia (Gombobaatar et al. 2011).
Human disturbance of Far Eastern Curlews includes recreation, fishing, shell-fishing, research and monitoring activities. Disturbance from human activities has a high energetic cost to shorebirds and may compromise their capacity to build sufficient energy reserves to undertake migration (Goss-Custard et al. 2006; Weston et al. 2012; Lilleyman et al. 2016). Disturbance that renders an area unusable is equivalent to habitat loss and can exacerbate population declines. Disturbance is greatest where increasing human populations and development pressures impact important habitats. Migratory shorebirds are most susceptible to disturbance during daytime roosting and foraging periods. As an example, disturbance of migratory shorebirds in Australia is known to result from aircraft over-flights, industrial operations and construction, artificial lighting, and recreational activities such as fishing, off-road driving on beaches, unleashed dogs and jet-skiing (Weston et al. 2012; Lilleyman et al. 2016). Careful planning can allow for both recreational activities and maintenance of shorebird populations in important coastal habitats (Stigner et al. 2016).
A recent study by Martin et al. (2014) examined the responses to human presence of an abundant shorebird species in an important coastal migration staging area. Long-term census data were used to assess the relationship between bird abundances and human densities and to determine population trends. In addition, changes in individual bird behaviour in relation to human presence were evaluated by direct observation of a resident shorebird species. The results showed that a rapid increase in the recreational use of the study area in summer dramatically reduced the number of shorebirds and gulls which occurred, limiting the capacity of the site as a post-breeding stop-over area (Martin et al. 2014). In addition, the presence of people at the beach significantly reduced the time that resident species spent consuming prey. Martin et al. (2014) found negative effects of human presence on bird abundance remained constant over the study period, indicating no habituation to human disturbance in any of the studied species. Moreover, although intense human disturbance occurred mainly in summer, the human presence observed was sufficient to have a negative impact on the long-term trends of a resident shorebird species. Martin et al. (2014) suggested that the impacts of disturbance detected on shorebirds and gulls may be reversible through management actions that decrease human presence. The authors suggest minimum distances for any track or walkway from those areas where shorebirds are usually present, particularly during spring and summer, as well as appropriate fencing in the most sensitive areas.
Tidal flats in the Yellow Sea frequently have hundreds of people collecting sea food and undertaking aquaculture activities. In some areas where bivalve spat has been seeded out on to tidal flats fireworks are used to deliberately scare birds away, and firecrackers may be used by photographers to make birds fly for spectacular photographs (D.S. Melville unpublished). Disturbance from tourist camps and resorts near large lakes and rivers is also influence migrating individuals in Mongolia (Gombobaatar et al. 2011).
Shorebird habitats are threatened by the chronic accumulation and concentration of pollutants. Chronic pollution may arise from both local and distant sources. Migratory shorebirds may be exposed to chronic pollution while utilising non-breeding habitats and along their migration routes, although the extent and implications of this exposure remains largely unknown although some studies have been conducted in the Republic of Korea (Kim et al. 2007a, b; Kim & Koo 2008; Kim et al. 2009). In their feeding areas, shorebirds are most at risk from bioaccumulation of human-made chemicals such as organochlorines from herbicides and pesticides and industrial waste. High levels of DDT are still found in many parts of China’s Yellow Sea coast, mostly apparently from anti-fouling paint used on wooden fishing boats (Melville et al. 2016). Agricultural, residential and catchment run-off carries excess nutrients, heavy metals, sediments and other pollutants into waterways, and eventually wetlands. Gold and other mining activities and pollution of wetlands, illegal fishing activities using gill nets, and abandoned gill nets on shore are potential impacts on the species in Mongolia (Gombobaatar et al. 2011). Shorebirds could be at risk from marine microplastics (Sutherland et al.2012), as these birds prey on invertebrates that are known to ingest microplastics by filter-feeding. This gap in our current knowledge provides an opportunity for directed research.
Wetlands and intertidal habitats are threatened by acute pollution caused by, for example, oil or chemical spillage (Melville 2015). Acute pollution generally arises from accidents, such as chemical spills from shipping, road or industrial accidents. Generally, migratory shorebirds are not directly affected by oil spills, but the suitability of important habitat may be reduced for many years through catastrophic loss of marine benthic food sources.
3.2 Threat prioritization
Each of the threats outlined above has been assessed to determine the risk posed to Far Eastern Curlew populations using a risk matrix. This in turn determines the priority for actions outlined in Section 5. The risk matrix considers the likelihood of an incident occurring and the population level consequences of that incident. Threats may act differently in different locations and populations at different times of year, but the precautionary principle dictates that the threat category is determined by the group at highest risk. Population-wide threats are generally considered to present a higher risk.
The risk matrix uses a qualitative assessment drawing on peer reviewed literature and expert opinion. In some cases the consequences of activities are unknown. In these cases, the precautionary principle has been applied. Levels of risk and the associated priority for action are defined as follows:
Very High - immediate mitigation action required
High - mitigation action and an adaptive management plan required, the precautionary principle should be applied
Moderate – obtain additional information and develop mitigation action if required
Low – monitor the threat occurrence and reassess threat level if likelihood or consequences change