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Yubu Island is located within the estuary of the Geum River, South Chungcheong Province , Korea. The island is surrounded by a broad and sandy mudflat, which is typical in the west coast of Korea, and is located 4km off from Gunsan City. Less than 100 humans live on the island, occupying 30 houses. After we discovered that this island was a very important waterbird habitat especially for the East Asian subspecies of the Eurasian oystercatcher, Haematopus ostralegus osculans. Waterbirds were monitored once every month from August 1999 to July 2000. The highest number of oystercatchers counted was 3,200 in December 1999, and the birds seemed to remain in the area continuously from September to next February. About 200 breeding and non-breeding birds remained during the breeding season. In August, early migrants returned to the island, with the number reaching 1,060 individuals. This island is also very important for other waterbirds. Endangered or significant species occurring at this site, and their maximum counts were: chinese egret Egretta eulophotes (5), black-faced spoonbill Platalea minor (17), brant Branta bernicla (1), common shelduck Tadorna tadorna (8,000), hooded crane Grus monacha (2), spoon-billed sandpiper Ewynorhynchus pygmeus (7), dunlin Calidris alpina (6,500), great knot Calidris tenuirostris (24,000), far eastern curlew Numenius madagascariensis (2,500), spotted greenshank Tringa guttifer (4) and Saunders's gull Larus saundersi (1,200). During the 12 month survey period, we observed 52 waterbird species and the total of the maximum counts for the separate species was 73,308, implying that perhaps 150,000 birds could be using the immediate area, if a turnover rate of 2 was assumed.

Great Knots (Calidris tenuirostris) make one of the longest migratory flights in the avian world, flying almost 5500 km from Australia to China during northward migration. We measured basal metabolic rate (BMR) and body composition in birds before and after this flight and found that BMR decreased 42%. The mass-specific BMR based on lean mass decreased 33%. We also starved a group of pre-migratory Great Knots in captivity to determine whether they showed the same reduction in BMR without having undergone the hard work of flight. The captive birds showed a similar range and reduction of BMR values as the wild birds. Exponents of relationships between BMR and body mass in different comparisons were high, indicating large changes in BMR as a function of body mass. Analysis of the body composition of ten wild and three captive birds found that the flight muscle mass and intestine mass positively correlated with BMR.

Great Knots (Calidris tenuirostris) make one of the longest migratory flights in the avian world, flying almost 5500 km from Australia to China during northward migration. We measured basal metabolic rate (BMR) and body composition in birds before and after this flight and found that BMR decreased 42%. The mass-specific BMR based on lean mass decreased 33%. We also starved a group of pre-migratory Great Knots in captivity to determine whether they showed the same reduction in BMR without having undergone the hard work of flight. The captive birds showed a similar range and reduction of BMR values as the wild birds. Exponents of relationships between BMR and body mass in different comparisons were high, indicating large changes in BMR as a function of body mass. Analysis of the body composition of ten wild and three captive birds found that the flight muscle mass and intestine mass positively correlated with BMR.La Tasa Metabolica Basal Disminuye durante Vuelos Migratorios de Larga Distancia en Calidris tenuirostrisResumen. Calidris tenuirostris realiza uno de los vuelos migratorios más largos entre las aves, volando desde Australia hasta China durante la migración al norte. Medimos la tasa metabólica basal (TMB) y la composición corporal en aves antes y después del vuelo y encontramos que TMB se reduce en 42%. La TMB específica por masa, o sea la TMB corregida por masa magra, se redujo en 33%. También expusimos un grupo premigratorio de Calidris tenuirostris a un periodo de ayuno en cautiverio, para determinar si mostraban una tasa de reducción similar en la TMB sin haber soportado la dura tarea de volar. Las aves en cautiverio mostraron un rango y una reducción de los valores de la TMB similares a los de las aves en libertad. Los exponentes de la relación entre TMB y masa corporal en diferentes comparaciones fueron altos, indicando grandes cambios de la TMB en función de la masa corporal. El análisis de la composición corporal de diez aves libres y tres en cautiverio mostró que la masa de los músculos del vuelo y la masa de los intestinos esta positivamente correlacionada con la TMB.

We studied changes in body composition in great knots, Calidris tenuirostris, before and after a migratory flight of 5,400 km from northwest Australia to eastern China. We also took premigratory birds into captivity and fasted them down to their equivalent arrival mass after migration to compare organ changes and nutrient use in a low-energy-turnover fast with a high-energy-turnover fast (migratory flight). Migrated birds were as economical as any fasting animal measured yet at conserving protein: their estimated relative protein contribution (RPC) to the energy used was 4.0%. Fasted birds had an estimated RPC of 6.8% and, consequently, a much lower lean mass and higher fat content for an equivalent body mass than migrated birds. Lean tissue was catabolized from most organs in both groups, except the brain. Furthermore, a principal components biplot showed that individuals were grouped primarily on the basis of overall organ fat or lean tissue content rather than by the size of specific organs. This indicates that organ changes during migratory flight are similar to those of a low-energy fast, although the length of the fast in this study probably accentuated organ reductions in some functional groups. Whether the metabolic characteristics of a flying migratory fast follow the three-phase model described in many inactive fasting animals is unclear. We have some evidence for skeletal fat being catabolized without phase 3 of a fast having been reached.

Since the early 1960s it has been held that migrating birds deposit and use only fat as fuel during migratory flight, with the non-fat portion of the body remaining homeostatic. Recent evidence from field studies has shown large changes in organ sizes in fuelling birds, and theory on fuel use suggests protein may be a necessary fuel during flight. However, an absence of information on the body condition of migrants before and after a long flight has hampered understanding of the dynamics of organs during sustained flight. We studied body condition in a medium-sized shorebird, the great knot (Calidris tenuirostris), before and after a flight of 5400 km from Australia to China during northward migration. Not only did these birds show the expected large reduction in fat content after migration, there was also a decrease in lean tissue mass, with significant decreases in seven organs. The reduction in functional components is reflected in a lowering of the basal metabolic rate by 46%. Recent flight models have tried to separate the `flexible’ part of the body from the constant portion. Our results suggest that apart from brains and lungs no organs are homeostatic during long-distance flight. Such organ reductions may be a crucial adaptation for long-distance flight in birds.

Summary: All known published and unpublished Great Knot Calidris tenuirostris breeding records, and probable breeding indications, have been reviewed. For 15 sites, breeding is confirmed by nests or unfledged chicks. The available information allows a general delineation of the breeding range to be made, although in some cases this is very approximate. The species occupies alpine and subalpine habitats in north-east Siberia and north Far East Russia at, and above, the upper tree line, at altitudes below 1000 m asl in the eastern half and usually above 1000 m asl in the western half of the breeding range. Vegetation mapping is used to assist in defining the probable breeding range. Literature, specimens and unpublished data from several observers are used to characterise the migrations of Great Knot within the Russian part of the East Asian‐Australasian Flyway. On northward migration, birds pass nonstop through the region for a few days in late May; a limited number of emergency stop-over sites have been identified. In contrast to previous views, only a few non-breeding Great Knots occur on the Russian Far East coast. Post-breeding migration starts in late June and seems to occur in three waves in the northern Sea of Okhotsk up to early September. There are indications that non-breeders, failed breeders and females migrate southward first, followed by males which have bred successfully. The final wave consists of young birds. In the more southern regions, the first migration wave is not pronounced, and migration of young birds lasts through October. Estuaries and bays in the north-eastern and north-western parts of the Sea of Okhotsk and in northern Sakhalin Island are very important staging areas on southward migration. These are almost certainly being used for refuelling before long non-stop flights further south towards Australia.

Evidence-based protection of migratory birds at flyway levels requires a solid understanding of their use of 'stopping sites' during migration. To characterize the site use of northward-migration great knots Calidris tenuirostris in China, we compared length of stay and fuel deposition during northward migration at areas in the south and the north of the Yellow Sea, a region critical for migrating shorebirds. Radio-tracking showed that at the southern site great knots stayed for only short periods (2.3 ± 1.9 d, n = 40), and bird captures showed that they did not increase their mean body mass while there. In the north birds stayed for 1 month (31.0 ± 13.6 d, n = 22) and almost doubled their mean body mass. Fuel consumption models suggest that great knots departing from the northern Yellow Sea should be able to fly nonstop to the breeding grounds, whereas those from the south would require a refueling stop further north. These results indicate that the study sites in the northern and southern Yellow Sea serve different roles: the southern site acts as a temporary stopover area that enables birds with low fuel stores to make it to main staging areas further north, while the northern site serves as the critical staging site where birds refuel for the next leg of their migration. The rapid turnover rate in the southern Yellow Sea indicates that many more birds use that area than are indicated by peak counts. Differential use of the southern and northern sites indicates that both play crucial roles in the ability of great knots to migrate successfully. © 2013 the Authors. Journal of Avian Biology

Migrating birds make the longest non-stop endurance flights in the animal kingdom. Satellite technology is now providing direct evidence on the lengths and durations of these flights and associated staging episodes for individual birds. Using this technology, we compared the migration performance of two subspecies of bar-tailed godwit Limosa lapponica travelling between non-breeding grounds in New Zealand (subspecies baueri) and northwest Australia (subspecies menzbieri) and breeding grounds in Alaska and eastern Russia, respectively. Individuals of both subspecies made long, usually non-stop, flights from non-breeding grounds to coastal staging grounds in the Yellow Sea region of East Asia (average 10 060 +/- SD 290 km for baueri and 5860 +/- 240 km for menzbieri). After an average stay of 41.2 +/- 4.8 d, baueri flew over the North Pacific Ocean before heading northeast to the Alaskan breeding grounds (6770 +/- 800 km). Menzbieri staged for 38.4 +/- 2.5 d, and flew over land and sea northeast to high arctic Russia (4170 +/- 370 km). The post-breeding journey for baueri involved several weeks of staging in southwest Alaska followed by non-stop flights across the Pacific Ocean to New Zealand (11 690 km in a complete track) or stopovers on islands in the southwestern Pacific en route to New Zealand and eastern Australia. By contrast, menzbieri returned to Australia via stopovers in the New Siberian Islands, Russia, and back at the Yellow Sea; birds travelled on average 4510 +/- 360 km from Russia to the Yellow Sea, staged there for 40.8 +/- 5.6 d, and then flew another 56807180 km to Australia (10 820 +/- 300 km in total). Overall, the entire migration of the single baueri godwit with a fully completed return track totalled 29 280 km and involved 20 d of major migratory flight over a round-trip journey of 174 d. The entire migrations of menzbieri averaged 21 940 +/- 570 km, including 14 d of major migratory flights out of 154 d total. Godwits of both populations exhibit extreme flight performance, and baueri makes the longest (southbound) and second-longest (northbound) non-stop migratory flights documented for any bird. Both subspecies essentially make single stops when moving between non-breeding and breeding sites in opposite hemispheres. This reinforces the critical importance of the intertidal habitats used by fuelling godwits in Australasia, the Yellow Sea, and Alaska.

We studied the diet and foraging behaviour of the Great Knot Calidris tenuirostris and to lesser extent of the Red Knot Calidris canutus rogersi and other waders at Roebuck Bay, Broome, Western Australia, in March-May 1991, the period of northward migration. Visual feeding observations, benthic fauna sampling and faecal analysis showed that the diet of Great Knots consisted mainly of bivalves. The total zoobenthic biomass in Roebuck Bay averaged 13.9 g ash free dry mass (AFDM) m-2, of which 5.7 and 6.0 g AFDM m-2 were available (sensu Zwarts et al. 1992) to Red Knots and Great Knots, respectively. The profitabilities of several possible prey types are discussed and compared with the recorded diet. Intake rates of Great Knots were estimated on the basis of recorded prey intake (0.24 mg AFDM s-1) and defaecation rates (0.33 mg AFDM s-1), and used to calculate mass gains prior to northward migration. The repercussions of the large tidal range on foraging possibilities are discussed. Changes in tidal regime may mean that Great Knots do not always have access to their preferred feeding sites. We indicate that the array of prey types available to, and taken by, Great Knots is much greater in Roebuck Bay than in the Wadden Sea. We discuss the repercussions of diet diversity on wader distribution. When compared with other springboard areas such as the Banc d'Arguin in Mauritania and the Wadden Sea in western Europe, the available Roebuck Bay benthic food stocks are larger.

SummaryThe coast of Bohai Bay, north-western Yellow Sea, is critical for waterbirds migrating along the East Asia-Australasian Flyway. Between 1994 and 2010, a total of 450 km2of offshore area, including 218 km2of intertidal flats (one third of the original tidal area in the bay), has been reclaimed along the bay for two industrial projects. This has caused the northward migrants to become concentrated in an ever smaller remaining area, our core study site. The spring peak numbers of two Red Knot subspecies in the East Asia-Australasian Flyway,Calidris canutus piersmaiandC. c. rogersi, in this so far little affected area increased from 13% in 2007 to 62% in 2010 of the global populations; the spring peak numbers of Curlew SandpiperC. ferrugineaincreased from 3% in 2007 to 23% in 2010 of the flyway population. The decline in the extent of intertidal mudflats also affected Relict GullsLarus relictus, listed by IUCN as ‘Vulnerable’; during normal winters 56% of the global population moved from the wintering habitats that were removed in Tianjin to the relatively intact areas around Tangshan. Densities of wintering Eurasian CurlewNumenius arquata, and spring-staging Broad-billed SandpiperLimicola falcinellusand SanderlingCalidris albahave also increased in the remaining areas. With the proposed continuation of land reclamation in Bohai Bay, we predict waterbird densities in the remaining areas to increase to a point of collapse. To evaluate the future of these fragile, shared international resources, it is vital to promote an immediate conservation action plan for the remaining coastal wetlands in this region, and continued population monitoring to determine the effects of this action.

We monitored numbers of Red Knots (Calidris canutus) staging in Bohai Bay, China (39 degrees 02'N, 118 degrees 15'E) on northward migration. Knots were identified to subspecies, and we systematically searched for colour-banded birds from the non-breeding grounds. We modelled migratory turnover, and revised estimates of flyway population using recently published counts from the non-breeding grounds. Two Russian-breeding subspecies occurred at our study site: C. c. rogersi (migrating to Chukotka), and C. c. piersmai (migrating to the New Siberian Islands); they co-occur on non-breeding grounds in Australia and New Zealand, but differ markedly in timing of migration. We conservatively estimate that our study site, comprising only 20 km of coastline, was used by over 45% of the combined world population of adult C. c. rogersi and C. c. piersmai - a conclusion supported by the independent data on frequency of resighting of colour-banded birds from north-western Australia and New Zealand. Much of this vital staging area is now being destroyed through construction of the Caofedian Industrial Zone and more westerly developments, which comprise only some of the many tidal flat 'reclamation' projects in the region. Preservation of the remaining tidal flats of Bohai Bay is essential to the conservation of Red Knots in the East Asian-Australasian Flyway.

High tides force shorebirds from intertidal feeding areas to sites known as roosts. We investigated the roost selection of great knots, Calidris tenuirostris, and red knots, Calidris canutus, on a tropical coastline in northwestern Australia, assessing several roost attributes and recording the frequency of use of each site through automatic radiotelemetry. To model roost choice we used two approaches: (1) conditional logistic regression models that assumed roost selection to be a trade-off based on a probabilistic assessment of several environmental characteristics; and (2) bounds-based models that assumed that birds selected the nearest roost site to their feeding grounds, provided that threshold values for certain environmental characteristics were met. Bounds-based models were more effective, and we suggest that they offer a closer approach to real roost choice mechanisms. By day, roost choice was affected by distance from the feeding area and microclimate; birds selected nearby roosts where they could stand on cool, wet substrates. Different roost selection criteria were used at night when birds chose safer, but more distant, roosts. Models that assumed that roost choice was influenced by recent experience of roost sites performed better than models that assumed constant assessment of roost quality. This effect was significant only at night, suggesting that memory was used more when information on roost quality was limited. Evidence that roost availability may influence selection of foraging areas is also presented. Our results suggest that shorebirds select roosts by using simple mechanisms, making roost choice models a potentially valuable tool in conservation planning. (c) 2006 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Migratory shorebirds that live in the tropics prior to embarking on long (> 5000 km) flights may face heat-load problems. The behaviour of a large sandpiper, the Great Knot (Calidris tenuirostris), was studied in Roebuck Bay, north-west Australia, from February to April 2000. We determined the incidence of heat-reduction behaviour in foraging and roosting birds in relation to breeding-plumage score ( an index of migratory preparation) and microclimate variables. Heat-reduction behaviour ( primarily raising the back feathers) was significantly related to breeding-plumage score and solar radiation. Raising back feathers may reduce the external heat load for a bird, or increase convective or cutaneous evaporative cooling. The results suggest that managing heat loads in tropical-wintering waders may become more difficult close to departure on migration.

To determine whether avian species are susceptible to infection with Gymnophalloides seoi (a human-infecting intestinal trematode), we exposed 7 species of birds with metacercariae obtained from oysters. The birds were necropsied at days 2, 4, and 6 postinfection (PI). The highest worm recovery at day 6 PI was obtained from the Kentish plover (Charadrius alexandrinus; mean = 56.0%), followed by the Mongolian plover (C. mongolus; 49.3%), and the grey plover (Pluvialis squatarola; 32.3%). In contrast, no mature worms were recovered from the great knot (Calidris tenuirostris), dunlin (C. alpina), black-tailed gull (Larus crassirostris), and mallard (Anas platyrhynchos). Among the plovers, the worms attained the greatest size at day 6 PI (254.1 x 190.4 microm) in the Kentish plover, with a significantly higher number of eggs in the uterus. The 3 species of plovers are highly susceptible to experimental G. seoi infection, suggesting that they could play a role as definitive hosts for these worms in nature.

The louse genus Lunaceps Clay and Meinertzhagen, 1939, parasitic on shorebirds (Charadriiformes: Scolopacidae) is re-vised. Six new species and one new subspecies of Lunaceps Clay and Meinertzhagen, 1939 parasitic on shorebirds (Char-adriiformes, Scolopacidae) are described. They are L. enigmaticus sp. nov. from Stilt Sandpiper Micropalama himantopus (Bonaparte, 1826), L. kukri sp. nov. from Long-billed Curlew Numenius americanus Bechstein, 1812, L. mintoni sp. nov.from Great Knot Calidris tenuirostris (Horsfield, 1821), L. rothkoi sp. nov. from Buff-breasted Sandpiper Tryngites sub- ruficollis (Vieillot, 1819), L. schismatus sp. nov. from Dunlin Calidris alpina (Linnaeus, 1758), L. superciliosus fromSharp-tailed Sandpiper Calidris acuminata (Horsfield, 1821) and Long-toed Stint Calidris subminuta (Middendorff,1853), and L. numenii madagascariensis ssp. nov. from Far Eastern Curlew Numenius madagascariensis (Linnaeus,1766). Furthermore, the species L. cabanisi Timmermann, 1954, and L. pusillus are placed as new junior synonyms of L. incoenis (Kellogg and Chapman, 1899); the species L. haematopi Timmermann, 1954, L. oliveri Timmermann, 1954, and L. husainii Ansari, 1956, are placed as new junior synonyms of L. numenii numenii (Denny, 1842), L. numenii phaeopi (Denny, 1842), and L. falcinellus Timmermann, 1954, respectively, and the subspecies L. holophaeus timmermanni Bechet, 1968, is regarded as a new junior synonym of L. falcinellus Timmermann, 1954. Lunaceps limosella limosa Bechet, 1968, which was previously considered a junior synonym of L limosella Timmermann, 1954, is resurrected as avalid species. Lunaceps wilsoni Carriker, 1956, is considered a nomen dubium, and L. parabolicus Eichler (in Nietham-mer), 1953, is removed to the genus Quadraceps Clay and Meinertzhagen, 1939 as Quadraceps parabolicus comb. nov.,although its status in Quadraceps needs further attention. All species and subspecies of Lunaceps are illustrated and rede-scribed, and a key is provided for their identification. Three populations, from which only poor or limited data are available, are placed as incerta sedis.

Adult worms of Parvatrema spp. (Digenea: Gymnophallidae) were found in the intestines of 2 species of migra- tory birds, i.e., a great knot, Calidris tenuirostris, and 2 Mongolian plovers, Charadrius mongolus, in the coastal area of Gunsan-si, Jeollabuk-do in October 2009. The recovered Parvatrema worms were 79 in total number and composed of 2 species. The worms from a great knot were 289 mm in length with the oral and ventral sucker ratio of 2 : 1. They had a sin- gle vitellarium, and their intrauterine eggs were 25.0 × 17.5 mm in size. These findings were compatible with P. duboisi (Dollfus, 1923) Bartoli, 1974 (syn. P. timondavidi Bartoli, 1963). The worms recovered from the Mongolian plovers were smaller in length than P. duboisi and had 2 vitellaria. The oral and ventral sucker ratio was 2.5 : 1, and the eggs were 17.5 × 8.8 mm in size. These worms were assigned to be P. homoeotecnum James, 1964. This is the first report on the natur- al final hosts of Parvatrema spp. in Korea.

Zinc, copper, lead and cadmium were measured in the livers, kidneys and bones of Terek Sandpipers (Xenus cinereus), Great Knots (Calidris tenuirostris) and Red-necked Stints (Calidris ruficollis) from the Okgu Mudflat, Korea. Zinc concentrations in bones were significantly higher in Terek Sandpipers than the other two species and differed among tissues in Terek Sandpipers. Copper concentrations in kidneys and bones but not livers differed among species. Copper concentrations in Terek Sandpipers and Great Knots differed among tissues. Zinc and copper concentrations from this study were similar to those reported for other shorebirds. Lead concentrations significantly differed among all species for each tissue and among tissues for each species. Cadmium concentrations were significantly different among species for all tissues and among tissues in Great Knots and Red-necked Stints. In Red-necked Stints, lead and cadmium concentrations in each tissue were higher than the background levels for wild birds and both metals were considerably greater that reported previously for shorebirds. Cadmium concentrations in Terek Sandpipers and Great Knots were similar to concentrations reported in other shorebirds. In Terek Sandpipers and Great Knots, lead concentrations showed chronic exposure but not in Red-necked Stints. Cadmium concentrations showed chronic exposure in all three shorebird species.

Since the early 1960s it has been held that migrating birds deposit and use only fat as fuel during migratory flight, with the non-fat portion of the body remaining homeostatic. Recent evidence from field studies has shown large changes in organ sizes in fuelling birds, and theory on fuel use suggests protein may be a necessary fuel during flight. However, an absence of information on the body condition of migrants before and after a long flight has hampered understanding of the dynamics of organs during sustained flight. We studied body condition in a medium-sized shorebird, the great knot (Calidris tenuirostris), before and after a flight of 5400 km from Australia to China during northward migration. Not only did these birds show the expected large reduction in fat content after migration, there was also a decrease in lean tissue mass, with significant decreases in seven organs. The reduction in functional components is reflected in a lowering of the basal metabolic rate by 42% [corrected]. Recent flight models have tried to separate the 'flexible' part of the body from the constant portion. Our results suggest that apart from brains and lungs no organs are homeostatic during long-distance flight. Such organ reductions may be a crucial adaptation for long-distance flight in birds.