Search

South-east Asia's diverse coastal wetlands, which span natural mudflats and mangroves to man-made salt pans, offer critical habitat for many migratory waterbird species in the East Asian–Australasian Flyway. Species dependent on these wetlands include nearly the entire population of the Critically Endangered spoon-billed sandpiper Calidris pygmaea and the Endangered spotted greenshank Tringa guttifer, and significant populations of several other globally threatened and declining species. Presently, more than 50 coastal Important Bird and Biodiversity Areas (IBAs) in the region (7.4% of all South-east Asian IBAs) support at least one threatened migratory species. However, recent studies continue to reveal major knowledge gaps on the distribution of migratory waterbirds and important wetland sites along South-east Asia's vast coastline, including undiscovered and potential IBAs. Alongside this, there are critical gaps in the representation of coastal wetlands across the protected area networks of many countries in this region (e.g. Viet Nam, Indonesia, Malaysia), hindering effective conservation. Although a better understanding of the value of coastal wetlands to people and their importance to migratory species is necessary, governments and other stakeholders need to do more to strengthen the conservation of these ecosystems by improving protected area coverage, habitat restoration, and coastal governance and management. This must be underpinned by the judicious use of evidence-based approaches, including satellite-tracking of migratory birds, ecological research and ground surveys.

Background The Black-faced Spoonbill (Platalea minor) is a globally threatened species, nesting mainly in western Korea with smaller numbers breeding in Liaoning Province, China, and Far East Russia. Recent winter field surveys to estimate the species’ population size were almost totally conducted in coastal areas, but tracking studies showed that some individuals now winter inland. To ensure its long-term survival, we need a more comprehensive assessment of the current distribution and abundance of the species. Methods We combined the most recent count data and satellite tracking information to update existing information about the population abundance and distribution of the Black-faced Spoonbill at all stages of its annual life cycle, and how these have changed during 2004–2020. Results Black-faced Spoonbills mainly breed on the west coast of the Korean peninsula, while immature birds show a wider summer distribution throughout Yellow Sea coastal areas, when a few remain on wintering sites in the south. Combined tracking results and mid-winter counts confirmed known wintering sites on the east and south coasts of China, but showed that the species also winters on wetlands in the Yangtze River floodplain and in Southeast Asia. During 2004–2020, counts of wintering birds in coastal habitats increased from 1198 to 4864, with numbers wintering on the island of Taiwan contributing most to the overall increase. Latest counts found 5222 in 2021. We also identify key wintering and stopover sites as well as their current conservation status. Conclusions This study revised the known summering and wintering ranges of the Black-faced Spoonbill and assessed the conservation status of key sites based on a combination of field survey and satellite tracking data. We recommend prioritisation of further field research to identify and survey inland wintering areas in the Yangtze River floodplain and summering areas of immature birds. More tracking of adult individuals and birds during spring migration is necessary to fill these information gaps. We also suggest establishing a Black-faced Spoonbill monitoring platform to store, share and show real-time distribution range and population abundance data.

BackgroundThe Eurasian Spoonbill (Platalea leucorodia) occurs throughout Eurasia and North and sub-Saharan Africa, with three recognized subspecies and six geographically distributed populations. However, in China, we knew almost nothing about migration routes, habitat use and effectiveness of current site protection measures for this species.MethodsWe deployed Global Positioning System/Global System for Mobile Communications (GPS/GSM) satellite trackers on 29 Eurasian Spoonbills captured in summer in Mongolia and northeastern China, to obtain complete migration routes data from 10 individuals from 19 complete migration episodes.ResultsTracking data showed no geographical overlap during the annual cycle in Eurasian Spoonbills marked in the two main summering areas. Birds marked in the Naoli River Basin in Heilongjiang Province, China, wintered along the Jiangsu coastline in China, while Eurasian Spoonbills from two discrete summering areas (in Inner and western Mongolia) overwintered inland in the Yangtze River floodplain of China. Excluding the single Inner Mongolian bird, spring migration was significantly faster than autumn migration in the other two groups of birds. Eurasian Spoonbills mainly used water, wetland and grassland habitats in summer, but almost exclusively water in winter. Lack of protection of staging sites used by all the birds in spring and poor levels of protection throughout the annual cycle for western Mongolian birds (5–22%) gives considerable cause for concern, although sites used in other time by East Mongolian and Naoli River birds in the rest of their annual life cycle enjoyed good levels of protection (49–95%).ConclusionsThese results revealed previously unknown relationships between summering and wintering areas, migration routes and stopover sites for Eurasian Spoonbills wintering in China, suggesting the existence of discrete biogeographical population units. They also identified winter habitat use of Eurasian Spoonbills in China, confirming open water habitats as being critical throughout the annual cycle, although based on small sample size, gaps in current site safeguard networks for these populations.

The Chinese Grass-babbler Graminicola striatus is a little-known grassland specialist with a broad distribution range in the Indo-Burma Biodiversity Hotspot. It is currently categorized as Vulnerable by the IUCN Red List of Threatened Species, with a suspected small population size and decline in habitat availability, and Hong Kong is considered the global stronghold. To understand its current conservation status, we conducted a range-wide breeding season field survey across southern China, which is the species major global distribution range, between 2016 and 2018, and discovered 14 new sites. These new localities range from lowland abandoned farmlands to upland anthropogenic grasslands, and 50% of these sites were within 250 m from major human settlements. We carried out a thorough literature and specimen collection review, and found no evidence of its presence in central China as established by widely-accepted distribution maps. Results of ecological niche modelling suggest a 18.9% reduction in its potential distribution in South China. Current area of suitable habitats in South China is 227,191 km2, and the recalculated global Extent of Occurrence is 1,307,543 km2, representing a huge range for a species which is not hunted and is tolerant to human disturbance and degraded habitats. In view of the new information on its distribution and inferred habitat suitability, we recommend the global conservation status of Chinese Grass-babbler warrant reassessment, and a Near Threatened category seems to be justified.

Many natural wetlands have been converted to human-influenced wetlands. In some instances, human-influenced wetlands could provide complementary habitats for waterbirds, compensating for the loss of natural wetlands. Inner Deep Bay in Hong Kong is composed of both natural and human-influenced wetlands and is under immense development pressure. From an ecology perspective, we need to understand if different wetland types play the same ecological role. To achieve this, we tracked nine little egrets (Egretta garzetta) using GPS loggers for 14 months to study their spatial ecology, home range, movement and habitat use. We found that over 88% of the home range of all individuals comprised of wetlands (commercial fishponds, mangrove, gei wai, channel, and intertidal mudflat). Among these wetland types, nearly all (seven of nine) individuals preferred commercial fishponds over other habitats in all seasons. Little egrets exhibited seasonal movement and habitat use among seasons, with largest home range, greatest movement, and most frequent visits to commercial fishponds in winter compared to spring and autumn. Our results highlight the significant role of commercial fishponds, providing a feeding ground for little egrets. However, other wetland types cannot be ignored, as they were also used considerably. These findings underscore the importance of maintaining a diversity of wetland types as alternative foraging and breeding habitats.

SummaryLong-term population monitoring is crucial to evaluate the effectiveness of conservation efforts. Systematic surveys of the endangered Black-faced Spoonbill Platalea minor, the rarest spoonbill species globally, are not possible during the breeding season as the largest breeding grounds are inaccessible to surveyors. Instead, we have examined population trend in this species during the winter by utilising a dataset of synchronised surveys conducted annually across 42 sites between 1997 and 2014. We found that the global population has increased from 535 individuals in 1997 to 2,726 in 2014, an annual increase of 8.0%. Population increases were more pronounced in protected sites and sites with low levels of human disturbance, indicating that control of human disturbance is crucial for conservation in this species. It is of concern that the wintering populations are highly clumped and the two largest populations have ceased to increase since 2012; research to investigate the underlying causes is urgently needed. Synchronised surveys in all known wintering sites should be continued to provide up-to-date data on the global population of this endangered species.

The southward migration strategies of shorebirds remain poorly understood in the East Asian–Australasian Flyway, yet understanding such strategies is critical to shorebird conservation. We estimate passage dates of 28 species of shorebird from count data at 15 sites to infer their migration strategies, using Thompson’s modelling approach. Our estimates of passage dates were consistent with available tracking data, giving us confidence that the modelled estimates were accurate. For large-bodied shorebirds, modelled departure dates from the northern Yellow Sea were similar to arrival dates throughout Australia, and their arrival dates in different regions in Australia were also similar, suggesting they flew directly from Asian staging areas to Australian non-breeding areas, or stopped only very briefly on the way. In contrast, small-bodied species apparently made multiple stops, especially in northern Australia, during their migration to their final non-breeding destinations. These differing patterns suggest that larger species in this Flyway depend on a small number of staging sites, whereas smaller species migrate in shorter steps and require additional staging sites between the northern Yellow Sea and Australasia. It is likely that some of these sites have not as yet been discovered, and that conservation of small shorebird species requires a more complete accounting of unknown and understudied staging sites.

SummaryDeclines in populations of the Critically Endangered Spoon-billed Sandpiper Calidris pygmaeus have been rapid, with the breeding population now perhaps numbering fewer than 120 pairs. The reasons for this decline remain unresolved. Whilst there is evidence that hunting in wintering areas is an important factor, loss of suitable habitat on passage and wintering areas is also of concern. While some key sites for the species are already documented, many of their wintering locations are described here for the first time. Their wintering range primarily stretches from Bangladesh to China. Comprehensive surveys of potential Spoon-billed Sandpiper wintering sites from 2005 to 2013 showed a wide distribution with three key concentrations in Myanmar and Bangladesh, but also regular sites in China, Vietnam and Thailand. The identification of all important non-breeding sites remains of high priority for the conservation of the species. Here, we present the results of field surveys of wintering Spoon-billed Sandpipers that took place in six countries between 2005 and 2013 and present species distribution models which map the potential wintering areas. These include known and currently unrecognised wintering locations. Our maximum entropy model did not identify any new extensive candidate areas within the winter distribution, suggesting that most key sites are already known, but it did identify small sites on the coast of eastern Bangladesh, western Myanmar, and the Guangxi and Guangdong regions of China that may merit further investigation. As no extensive areas of new potential habitat were identified, we suggest that the priorities for the conservation of this species are habitat protection in important wintering and passage areas and reducing hunting pressure on birds at these sites.

SummaryChina makes a unique and vital contribution to maintaining global and regional waterbird diversity and conservation. Despite considerable historical conservation efforts, the continued loss of waterbird diversity and abundance necessitates a contemporary review of Chinese sites of conservation significance. The Ecological Protection Red Line (EPRL) was proposed by China’s Central Government in 2013 to protect areas providing crucial ecosystem services and provides the opportunity for such a review to enhance waterbird conservation in China. By incorporating various sources of data, surveys and information, we identified a suite of sites of waterbird conservation significance in China, following the Ramsar Site Criteria/Important Bird and Biodiversity Area (IBA) Criteria. In total, we identified 422 sites, of which the existing 286 IBA sites formed the basis of the site safeguard network. Altogether, these sites of waterbird conservation significance constitute over 727,000 km2 (7.6% of China’s land surface). Over half of the area of these sites is outside China’s national nature reserves, thus confirming the importance and urgency of including them in the EPRL for the effective conservation of waterbird sites. We suggest that this assessment of sites of waterbird importance offers a useful model to apply to other taxa, such as terrestrial birds and mammals.

Spatial subsidies of energy and nutrients can influence the distribution of consumers in riparian habitats. This study compared the abundance and composition of bird assemblages and the availability of volant insect prey within the riparian zone (≤ 30 m from the stream) and further inland (100–250 m away) within a secondary forest in monsoonal Hong Kong. Replicated point-counts of birds and insect light trapping were conducted in each zone during the wet and dry season of 2006–2007. The biomass of adult aquatic insects in the riparian zone was nine to 12 times higher than inland during both seasons, however, total insect biomass (aquatic plus terrestrial insects) in the riparian zone was only 49 percent (wet season) and 18 percent (dry season) greater. More birds (both numbers of individuals and species) were recorded in the riparian zone, and this difference was particularly conspicuous during the wet season. Most of the wet-season difference was due to the greater number of insectivorous birds in the riparian zone (123% greater than inland), and may have reflected the relative availability of adult aquatic insects. These findings confirm the importance of riparian zones as feeding habitats for forest birds, and have implications for conservation planning and setting the boundaries of protected areas.

China’s coastal wetlands belong to some of the most threatened ecosystems worldwide. The loss and degradation of these wetlands seriously threaten waterbirds that depend on wetlands. The China Coastal Waterbird Census was organized by volunteer birdwatchers in China’s coastal region. Waterbirds were surveyed synchronously once every month at 14 sites, as well as irregularly at a further 18 sites, between September 2005 and December 2013. A total of 75 species of waterbirds met the 1 % population level Ramsar listing criterion at least once at one site. The number of birds of the following species accounted for over 20 % of the total flyway populations at a single site: Mute Swan (Cygnus olor), Siberia Crane (Grus leucogeranus), Far Eastern Oystercatcher (Haematopus osculans), Bar-tailed Godwit (Limosa lapponica), Spotted Greenshank (Tringa guttifer), Great Knot (Calidris tenuirostris), Spoon-billed Sandpiper (Calidris pygmeus), Saunders’s Gull (Larus saundersi), Relict Gull (Larus relictus), Great Cormorant (Phalacrocorax carbo), Eurasian Spoonbill (Platalea leucorodia), Black-faced Spoonbill (Platalea minor) and Dalmatian Pelican (Pelecanus crispus). A total of 26 sites supported at least one species of which their number met the 1 % criterion. Forty-two species met the 1 % criterion in the Yellow River Delta, Shandong; 29 at the Cangzhou coast, Hebei and 26 species at the Lianyungang coast, Jiangsu. The results highlight the international importance of China’s coastal wetlands for waterbirds. This study also demonstrates that participation of local birdwatchers in waterbird surveys results in data that are invaluable not only for understanding the current status of waterbirds in China’s coastal regions but also for waterbird conservation and management.

Feeding Black-faced Spoonbills (Platalea minor) were studied in four main areas along the coasts of South Korea, Taiwan, China and Vietnam. They fed on nekton, mainly fish and shrimps, varying in length between 2-21 cm that were caught by sweeping the bill in the water. The feeding behavior of a spoonbill is a chain of feeding and inter-feeding bouts. Each feeding bout started by putting the bill into the water and ended when the bill was taken out and any prey captured was swallowed. The times between feeding bouts were short and no or few steps were made. In a complete feeding bout, up to three functional phases were distinguished. These were successively (1) the attempt to locate a prey, (2) the attempt to catch the located prey, (3) the handling and swallowing of the prey. A feeding bout could end in any phase. A total of 1,684 feeding bouts were recorded of which 65% ended with swallowing prey. The mean outcome was 45.4 small ( 5 cm long) prey per 10 min. Tentative...

The Black-faced Spoonbill (Platalea minor) uses habitats that are intertidal or within 2-3 km from tidal areas for feeding and loafing. Habitats used for feeding are water bodies containing fish and shrimps and a relatively wide zone of shallow water with a depth ranging between 6 and 21 cm. The bottom consisted of fine sediments with no or little vegetation or other obstructions such as stones, twigs, branches and roots of trees, wide and deep channels, or debris. They have a preference for highly turbid water, but seemed indifferent to salinity, which was varied between 0‰ and 48‰. Such sites are found on flooded intertidal mudflats, and also in tidal lagoons, brackish pools, fishponds, and gei wai (traditional ponds for shrimp farming in mangrove areas). Feeding habitats have to contain suitable food and also be relatively safe. In contrast with the requirements for their feeding habitats, the choice of loafing areas is extensive, and includes places of relative safety: undisturbed, with an op...

The Black-faced Spoonbill (Platalea minor) has often been considered to be a mainly nocturnal feeder. The present study shows that this species is better classified as crepuscular, being predominantly active around sunrise and sunset, but they may also feed during the day and at night. The periods of twilight and the tides interact in the timing of feeding. On average, just over 4 hours per day (17%) is spent for feeding, about 19.5 h (81%) loafing and less than a half hour (1.6%) flying.

The bills of the spoonbills differ from the bills of most birds by being wider near the downward curved tip than in the middle, and having the mandibles dorso-ventrally extremely flattened. The mandibles have rounded lateral borders and lack cutting edges. The inward directed sides have a dense cover of thin parallel ridges on the distal parts and rows of teeth-like tubercles in the proximate parts. Their skeletons have numerous small pits in the distal parts especially along the edges and the insides. These pits are similar to the spaces for sensory corpuscles for touch in the bills of Scolopacidae (sandpipers, snipes) and are presumed to have the same function in spoonbills. The bill seems adapted for tactile feeding with lateral movements (sweeping) and for pecking, but not for probing into sediments. The wide gape with gular pouch allows the swallowing of rather large food items. The muscular layer of the gizzard is weakly developed and the gizzard is more a digestive pocket than a chewing organ such as occurs for grinding hard shells and grains in molluscivorous and granivorous birds. The long legs are laterally flattened, perhaps for minimising resistance and not-disturbing prey when walking in water during feeding; the partly webbed feet with long toes allow walking over soft mud bottoms.

We analysed the hypothesis of Weihs and Katzir (1994) that feeding spoonbills use their broad bills by sweeping it through the water to shed a vortex. This would result in a hydrodynamic suction on the bottom for catching prey immediately or during the next sweep besides providing some extra benefits. The basic assumptions appear to be erroneous. (1) A spoonbill does not mainly feed on small, benthic invertebrates, but mainly on nekton such as fish and shrimps. (2) The inner surface of the upper mandible of a spoonbill is not concave but convex. (3) During feeding, a spoonbill does not keep its bill tip close to the bottom independent of the water depth. The outcomes of the tests supporting the hypothesis do not hold and the suggested benefits are dubious. Therefore, we reject the hypothesis and the claim that the bill of a spoonbill is used as a hydrofoil. The discussed paper tried to give an explanation of the behaviour of a bird with the help of hydrodynamic formulae. The fundamental mistake in the paper is that the use of the formulae is based on wrong assumptions concerning the food of the bird, its feeding behaviour as well as its anatomical details. The tests with a bird kept in captivity suggesting a proof of the rightness of the hypothesis lack a proper connection to the situation in the wild. Spoonbills (Aves: Ciconiiformes: Threskiornithidae, genus Platalea) are large wading birds characterised by their extremely flattened bills that are widened in the distal parts. The six species are very similar in shape and behaviour, mainly differing in size, colour of legs, bills and other bare parts, and in distribution (Matheu and del Hoyo 1992). They feed tactilely by walking in shallow