Calidris Tenuirostris Research Articles

Tracking the full annual-cycle of the Great Knot, Calidris tenuirostris, a long-distance migratory shorebird of the East Asian-Australasian Flyway

The Great Knot Calidris tenuirostris is one of the iconic long-distance migratory species of the East Asian-Australasian Flyway. However, despite extensive flagging and banding efforts, very little is known about the migratory strategies and the breeding grounds of this species that spends the non-breeding season mainly on the northern shorelines of Australia. Using light-level geolocators deployed on Great Knots at Roebuck Bay (Western Australia), we describe the individual migration strategies, breeding locations and breeding-related behaviour. Based on data from eight successfully tracked individuals, we found that all except one migrated to the western part of the known breeding range. This was 2,000–2,500 km from the eighth individual that commenced breeding in the potentially sep- arated eastern part of the range. Light intensity and temperature profiles provided evidence that four of the birds successfully hatched chicks. Of the three which failed, one appeared to have laid a second clutch before failing again. Arrival at the breeding grounds and the laying of eggs were remarkably synchronous between individuals, as were the arrival dates back at Roebuck Bay. Departure from the breeding grounds was more spread out, partly dependent on breeding success and also as a result of females probably leaving the nesting area before males. The individual migration strategies confirmed the strong dependence of this species on the Yellow Sea as their major stopover site during both southward and northward migration. Furthermore, all individuals stopped at least once on their northward journey to the Yellow Sea from Australia. And in reverse, all individuals stopped at least once on the southward migration before arriving at the Yellow Sea coming from their Arctic breeding grounds. The results indicate that this species will most likely be further affected by the rapid habitat loss in the area of the Yellow Sea and other parts of the Chinese coastline.

Reclamation of tidal flats and shorebird declines in Saemangeum and elsewhere in the Republic of Korea

Saemangeum, in the Republic of Korea (ROK, commonly called South Korea) was one of the most important shorebird staging sites in the Yellow Sea. It supported at least 330 000 shorebirds annually between 1997 and 2001, including ∼30% of the world population of Great Knots (Calidris tenuirostris) during both northward and southward migration. Construction of a 33-km long sea-wall was completed in April 2006. We show that shorebird numbers at Saemangeum and two adjacent wetlands decreased by 130 000 during northward migration in the next two years and that all species have declined at Saemangeum since completion of the sea-wall. Great Knots were among the most rapidly affected species. Fewer than 5000 shorebirds were recorded at Saemangeum during northward migration in 2014. We found no evidence to suggest that most shorebirds of any species displaced from Saemangeum successfully relocated to other sites in the ROK. Instead, by 2011–13 nearly all species had declined substantially in the ROK since previous national surveys in 1998 and 2008, especially at more heavily reclaimed sites. It is likely that these declines were driven by increased mortality rather than movement to alternate staging sites given that other studies have shown concurrent declines in numbers and survival on the non-breeding grounds. This is the first study in the East Asian—Australasian Flyway to confirm declines of shorebirds at a range of geographical scales following a single reclamation project. The results indicate that if migratory shorebirds are displaced from major staging sites by reclamation they are probably unable to relocate successfully to alternate sites.

Simultaneous declines in summer survival of three shorebird species signals a flyway at risk

SummaryThere is increasing concern about the world's animal migrations. With many land‐use and climatological changes occurring simultaneously, pinning down the causes of large‐scale conservation problems requires sophisticated and data‐intensive approaches.Declining shorebird numbers along the East Asian–Australasian Flyway, in combination with data on habitat loss along the Yellow Sea (where these birds refuel during long‐distance migrations), indicate a flyway under threat.If habitat loss at staging areas indeed leads to flyway‐wide bird losses, we would predict that: (i) decreases in survival only occur during the season that birds use the Yellow Sea, and (ii) decreases in survival occur in migrants that share a reliance on the vanishing intertidal flats along the Yellow Sea, even if ecologically distinct and using different breeding grounds.Monitored from 2006–2013, we analysedseasonalapparent survival patterns of three shorebird species with non‐overlapping Arctic breeding areas and considerable differences in foraging ecology, but a shared use of both north‐west Australian non‐breeding grounds and the Yellow Sea coasts to refuel during northward and southward migrations (red knotCalidris canutus piersmai, great knotCalidris tenuirostris,bar‐tailed godwitLimosa lapponica menzbieri). Distinguishing two three‐month non‐breeding periods and a six‐month migration and breeding period, and analysing survival of the three species and the three seasons in a single model, we statistically evaluated differences at both the species and season levels.Whereas apparent survival remained high in north‐west Australia, during the time away from the non‐breeding grounds survival in all three species began to decline in 2011, having lost 20 percentage points by 2012. By 2012annualapparent survival had become as low as 0·71 in bar‐tailed godwits, 0·68 in great knots and 0·67 in red knots. In a separate analysis for red knots, no mortality occurred during the migration from Australia to China. In the summers of low summer survival, weather conditions were benign in the Arctic breeding areas.We argue that rapid seashore habitat loss in the Yellow Sea is the most likely explanation of reduced summer survival, with dire (but uncertain) forecasts for the future of these flyway populations. This interpretation is consistent with recent findings of declining shorebird numbers at seemingly intact southern non‐breeding sites.Policy implications. Due to established economic interests, governments are usually reluctant to act for conservation, unless unambiguous evidence for particular cause–effect chains is apparent. This study adds to an increasing body of evidence that habitat loss along the Yellow Sea shores explains the widespread declines in shorebird numbers along the East Asian–Australasian Flyway and threatens the long‐term prospects of several long‐distance migrating species. To halt further losses, the clearance of coastal intertidal habitat must stop now.

Identification of coastal wetlands of international importance for waterbirds: a review of China Coastal Waterbird Surveys 2005–2013

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.

Adjusting migration schedules at stopping sites: time strategy of a long-distance migratory shorebird during northward migration

Selection of timing to match optimal environments is crucial for migrants that breed at high latitudes where there is a narrow time window suitable for breeding. However, birds generally depart from non-breeding grounds in a broad time window. How birds adjust their migration schedule to match optimal timing of arrival at breeding grounds is largely unexplored. We radio-tracked Great Knots Calidris tenuirostris at stopping sites in the southern and northern Yellow Sea during the entire stopping periods to determine their time schedules during northward migration. Great Knots stayed for 40.7 ± 9.2 days (n = 11) in the whole Yellow Sea, with the early arrivals having a longer length of stay than the late arrivals. There was no significant difference in the length of stay between birds that arrived on various dates in the southern Yellow Sea, while the late arrivals spent less time during flights from the southern to the northern Yellow Sea, and stayed for a shorter time than the early arrivals in the northern Yellow Sea. We estimated that the later arrivals can still moult into full breeding plumage and deposit enough fuel for a flight to the breeding grounds before departure. We propose that early and latter migration are the two ends of migratory schedule, with the former adapting to unpredictable and rigorous environments and the latter to stable and favourable environments en route. Stopping sites play an important role for birds to adjust their migration schedule to meet optimal timing of arrival at migratory destination.

The importance of Yalu Jiang coastal wetland in the north Yellow Sea to Bar-tailed GodwitsLimosa lapponicaand Great KnotsCalidris tenuirostrisduring northward migration

SummaryBar-tailed GodwitsLimosa lapponicaand Great KnotsCalidris tenuirostrisare long-distance migratory shorebirds with declining numbers in the East Asian-Australasian Flyway. One of the most important staging sites for these two species during northward migration is Yalu Jiang coastal wetland in the north Yellow Sea. Historical counts have been limited to once a year and conducted at different periods; these yield inadequate data for population monitoring. We estimated the numbers of Bar-tailed Godwits and Great Knots and described their migration phenology during northward migration from 2010 to 2012 at the Yalu Jiang coastal wetland, using a combination of periodic area-wide counts over the migration period and a modelling approach that estimates passage times and total numbers of birds transiting. The mean arrival date forL. l. bauerigodwits was 29 March and mean departure date was 8 May. Corresponding dates were 11 April and 15 May forL. l. menzbierigodwits and 7 April and 14 May for Great Knots. We estimated that an annual average of over 68,000 Bar-tailed Godwits and 44,000 Great Knots used the area on northward migration from 2010–2012. Our results indicate that the Yalu Jiang coastal wetland supports on average at least 42% of the flyway’s northward-migratingL. l. bauerigodwits, 19% ofL. l. menzbierigodwits, and 22% of the Great Knots. Comparisons with historical counts conducted during peak migration periods indicate a 13% decline in Bar-tailed Godwits since 2004 and an 18% decline in Great Knots since 1999. Our results confirm that the study area remains the most important northward migration staging site for Bar-tailed Godwits and indicate that it has become the most important northward migration staging site for Great Knots along the flyway.

Optimal management of a multispecies shorebird flyway under sea-level rise.

Every year, millions of migratory shorebirds fly through the East Asian-Australasian Flyway between their arctic breeding grounds and Australasia. This flyway includes numerous coastal wetlands in Asia and the Pacific that are used as stopover sites where birds rest and feed. Loss of a few important stopover sites through sea-level rise (SLR) could cause sudden population declines. We formulated and solved mathematically the problem of how to identify the most important stopover sites to minimize losses of bird populations across flyways by conserving land that facilitates upshore shifts of tidal flats in response to SLR. To guide conservation investment that minimizes losses of migratory bird populations during migration, we developed a spatially explicit flyway model coupled with a maximum flow algorithm. Migratory routes of 10 shorebird taxa were modeled in a graph theoretic framework by representing clusters of important wetlands as nodes and the number of birds flying between 2 nodes as edges. We also evaluated several resource allocation algorithms that required only partial information on flyway connectivity (node strategy, based on the impacts of SLR at nodes; habitat strategy, based on habitat change at sites; population strategy, based on population change at sites; and random investment). The resource allocation algorithms based on flyway information performed on average 15% better than simpler allocations based on patterns of habitat loss or local bird counts. The Yellow Sea region stood out as the most important priority for effective conservation of migratory shorebirds, but investment in this area alone will not ensure the persistence of species across the flyway. The spatial distribution of conservation investments differed enormously according to the severity of SLR and whether information about flyway connectivity was used to guide the prioritizations. With the rapid ongoing loss of coastal wetlands globally, our method provides insight into efficient conservation planning for migratory species.

Differentiating between stopover and staging sites: functions of the southern and northern Yellow Sea for long‐distance migratory shorebirds

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.

The “Very Thankless Task”: Revision of Lunaceps Clay and Meinertzhagen, 1939 (Insecta: Phthiraptera: Ischnocera: Philopteridae), with descriptions of six new species and one new subspecies

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, andL. 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 timmermanniBechet, 1968, is regarded as a new junior synonym of L. falcinellus Timmermann, 1954. Lunaceps limosella limosaBechet, 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.

Monitoring of heavy metal contaminants using feathers of shorebirds, Korea

This study presents concentrations of iron, zinc, copper, lead and cadmium in the feathers of 3 shorebird species (n = 29) from Okgu Mudflat, Korea in the East Asian-Australian Migration Flyways. Lead concentrations (ANOVA, p < 0.001) in Red-necked Stints (geomean = 9.61 μg g(-1) dry weight) were higher than in Terek Sandpipers (geomean = 5.56 μg g(-1) dry weight) which in turn were higher than in Great Knots (geomean = 2.78 μg g(-1) wet weight). Cadmium concentrations (ANOVA, p < 0.001) were higher in Great Knots (geomean = 2.97 μg g(-1) wet weight) and in Red-necked Stints (geomean = 2.70 μg g(-1) dry weight) than in Terek Sandpipers (geomean = 0.33 μg g(-1) dry weight). Lead (r = 0.574, p < 0.01) and cadmium (r = 0.380, p < 0.05) concentrations between feathers and livers of shorebirds were significantly correlated. Lead concentrations in 65.5% (19 individuals) of shorebirds exceeded a toxicity threshold for feathers (4 μg g(-1) dry weight). Iron, zinc, copper, lead and cadmium concentrations in feathers were within the range of earlier studies for wild birds, but lead concentrations in Red-necked Stints were higher than those reported in other studies. Because lead concentrations in feathers and livers of Red-necked Stints were markedly higher than in other shorebirds, we suggest that Red-necked Stints were exposed to higher lead concentrations than the other shorebirds on their breeding or wintering grounds.

Survey and conservation of the critically endangered Spoon‐billed Sandpiper in Bangladesh

Survey and conservation of the critically endangered Spoon‐billed Sandpiper in Bangladesh

Diet of Great Knots (Calidris tenuirostris) during spring stopover at Chongming Dongtan, China

Variable and unpredictable food resources at stopover sites bring severe challenges to migrating shorebirds. Opportunistic foraging strategies, referring to shorebirds consuming prey in proportion to their availability, allow shorebirds to replenish fuel and nutrient reserves efficiently for continuing their migration. Chongming Dongtan, located in the Yangtze River estuary of eastern China, is the first major stopover site of shorebirds on the Chinese mainland during their northward migration. We investigated the diet of Great Knots (<i>Calidris tenuirostris</i>) at Chongming Dongtan during the spring stopovers of 2009 and 2010 through benthos sampling and dropping analysis. The benthos samples were categorized into gastropods, bivalves, polychaetes, crustaceans and insect larvae. Dropping analysis indicated that gastropods and bivalves constituted more than 70% of the diet of the Great Knot, with <i>Assiminea violacea</i> and <i>Corbicula fluminea</i> being the most frequently consumed. Chi-square tests indicated that for each prey category, there was no significant difference between the frequency of its occurrence in the benthos samples and dropping samples during the early stopover periods of 2009 and 2010 and during the late stopover periods of 2010. Although there was a statistically significant difference between the frequency of occurrence of prey in the total macrobenthos and in the droppings of the Great Knots during the late stopover period in 2009, the more abundant prey were more frequently consumed by the Great Knots. This suggests that Great Knots adopted an opportunistic foraging strategy during their stopover at Chongming Dongtan.

In Vitro Comparison of Mechanical and Degradation Properties of Equivalent Absorbable Suture Materials from Two Different Manufacturers

To compare the mechanical, knotting, and absorption properties of 3 synthetic absorbable suture materials (polyglactin 910, polydioxanone, poliglecaprone 25) from 2 different manufacturers (Huaiyin Medical Instruments Co. Ltd. and Ethicon Inc.). Suture material samples from the same manufacturing lot for each suture type and manufacturer. Part 1: 10 samples of each suture were incubated in bovine serum and tested for ultimate load and stiffness at days 0, 1, 7, 14, 21, and 28. Part 2: 10 knotted samples were similarly evaluated, without incubation. Huaiyin polydioxanone had a greater (P<.001) ultimate load on days 0, 1, and 7; and a consistently greater stiffness for the duration of the study, compared with the Ethicon polydioxanone. Ethicon poliglecaprone 25 had a greater ultimate load on days 0, 1, 7 (P<.001); on day 21 Huaiyin had a greater ultimate load. Ethicon poliglecaprone had greater stiffness on days 0, 1, 7 (P<.001). Ethicon polyglactin 910 had a greater (P<.001) ultimate load at all times and a greater stiffness (P<.001) at days 0, 1, 7, and 14 compared with Huaiyin polyglactin 910. Huaiyin polydioxanone and polyglactin 910 had greater knot breaking strengths than Ethicon equivalents (P<.001). Differences in mechanical properties exist between nominally identical suture materials from different manufacturers.

Avifauna at Spring season in Yubudo island, Korea

This study was conducted between March and July of 2010 in the area of Yubudo (Is.) in order to assess its avian fauna. A total of 39,121 counts of 37 species were observed over 5 sessions. Important dominant species included the dunlin (Calidris alpine) (48.0%), followed by the bar-tailed godwit (Limosa lapponica) (26.2%), far eastern curlew (Numenius madagascariensis) (5.2%) and the great knot (Calidris tenuirostris) (5.1%). Among the dominant species, the dunlin and the bar-tailed godwit showed significant increase in count, while the great knot showed a decrease. The far eastern curlew, eastern oystercatcher (Haematopus ostralegus) and the Indian curlew (Numenius arquata) did not show any significant difference when compared to previous studies, in terms of both migratory bird count and migratory pattern. Such migratory pattern of dominant species seems to be the result of large scale environmental changes.

Acute and/or chronic contaminations of heavy metals in shorebirds from 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.

Discovery ofParvatrema duboisiandParvatrema homoeotecnum(Digenea: Gymnophallidae) from Migratory Birds in Korea

Adult worms of Parvatrema spp. (Digenea: Gymnophallidae) were found in the intestines of 2 species of migratory 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 µm in length with the oral and ventral sucker ratio of 2 : 1. They had a single vitellarium, and their intrauterine eggs were 25.0 x 17.5 µm 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 x 8.8 µm in size. These worms were assigned to be P. homoeotecnum James, 1964. This is the first report on the natural final hosts of Parvatrema spp. in Korea.

First record of Great Knot Calidris tenuirostris for Namibia

First record of Great Knot Calidris tenuirostris for Namibia

Body Condition and Fuel Deposition Patterns of Calidrid Sandpipers During Migratory Stopover

We compared seasonal variations in body condition and fuel deposition patterns of five calidrid sandpipers at Chongming Dongtan (eastern China), a stopover site in the East Asian—Australasian Flyway. We tested the hypothesis that long-distance migrants show different body condition and fuel deposition patterns relative to those undertaking short-distance flights. Results indicated that the body condition and fuel deposition patterns of the sandpipers varied between the northward and southward migration seasons and between age-classes. Great Knots Calidris tenuirostris and Red Knots Calidris canutus migrate southwards on a long-distance nonstop flight from Chongming Dongtan to northwest Australia, while covering on the return flight a relatively short-distance between Chongming Dongtan and the north Yellow Sea region. Both species attained a significantly higher body condition at Chongming Dongtan during the southward than northward migration. Moreover, they showed a significant increase in body condition at Chongming Dongtan during northward migration stopover, which we see as a recovery from the long flight from Australia. In contrast, Red-necked Stints Calidris ruficollis and Long-toed Stints Calidris subminuta, employing series of relatively short-distance flights during migration, indicated no significant difference in departure body condition at Chongming Dongtan between seasons, nor significant increase in body condition during either migration stopover. Dunlins Calidris alpina on the other hand, showed a significantly higher body condition during northward than southward migration stopover, most likely in anticipation of the longer travelling distance after leaving Chongming Dongtan during northward migration. This study confirms that the body condition and fuel deposition patterns among shorebird species that undertake long-distance nonstop flights are different from those that undertake series of short-distance flights, suggesting that the comparison of body condition and fuel deposition patterns of calidrid sandpipers can be an important tool to understand their migration strategies.

Heavy metal concentrations in three shorebird species from Okgu Mudflat, Gunsan, Korea

Iron, zinc, copper, lead, and cadmium were measured in livers of three shorebird species from Okgu Mudflat, Korea in the East Asian-Australian migration flyways. Iron concentrations in red-necked stints (Calidris ruficollis) (geomean = 1,322 microg/g dw) were higher than in terek sandpipers (Xenus cinereus) (467 microg/g dw), and great knots (Calidris tenuirostris) (158 microg/g dw). Copper concentrations in great knots (85.8 microg/g dw) were significantly higher than in red-necked stints (15.9 microg/g dw) and terek sandpipers (10.4 microg/g dw). However, significant differences in zinc concentrations were not found in livers among shorebird species. Iron, zinc, and copper concentrations from this study were within the range of other shorebird studies. We suggest that essential elements such as iron, zinc, and copper are within normal range and are maintained there by normal homeostatic mechanism. Lead and cadmium concentrations differed among shorebird species; red-necked stints (geomeans 27.8 microg/g dw and 4.69 microg/g dw, respectively) were higher than in terek sandpipers (12.9 and 0.44 microg/g dw, respectively), and great knots (5.43 and 0.29 microg/g dw, respectively). Some red-necked stints exceeded toxic levels of lead and cadmium for wild birds. In livers of red-necked stints from Okgu Mudflat, lead and cadmium concentrations were higher than previously reported in other shorebirds.

ENDOGENOUS CIRCANNUAL RHYTHMICITY IN BODY MASS, MOLT, AND PLUMAGE OF GREAT KNOTS (CALIDRIS TENUIROSTRIS)

Abstract Four Great Knots (Calidris tenuirostris) were kept for six years in a constant-temperature indoor aviary. For two of those six years, they were kept under photoperiodic conditions that mimicked natural changes in daylength for wild birds, followed by four years under a constant photoperiod (light:dark cycle 12:12 h). Under cyclical “natural” photoperiods, three of the four birds maintained cycles of body mass and contour and flight-feather molt somewhat comparable to that of free-living birds, though the multiple mass peaks characteristic of northward migration were replaced by a single period of high body mass; the mass peaks for southward migration appeared to be absent. Contour-feather molts between nonbreeding and breeding plumages were delayed, and the period of wing molt was longer than in free-living birds. Under constant photoperiods, clear circannual phenotype cycles were maintained. The length of the period with elevated body mass tripled but was partly compensated by a shortening of th...