Seasonal change and habitat selection of shorebird community at the South Yangtze River Mouth and North Hangzhou Bay, China

Coastal regions are important habitats for migratory shorebirds. The aim of the study is to understand habitat use by migratory shorebirds and to develop a conservation strategy in the sustainable use of wetlands. From March 2004 to January 2005, we conducted a seasonal shorebirds census in ten coastal habitats along the South Yangtze River mouth and North Hangzhou Bay, simultaneously examining the relative seasonal abundance of shorebirds and their spatial distribution. A total of 25 species were identified, the dominant seasonal species were Great Knot (Calidris tenuirostris), Sharp-tailed Sandpiper (Calidris alpine) and Red-necked Stint (Calidris ruficollis) in spring; Kentish Plover (Charadrius alexandrinus), Common Greenshank(Tringa nebularia) and Lesser Sand Plover (Charadrius mongolus) in summer; Kentish Plover, Red-necked Stint and Common Greenshank in autumn; Dunlin(Calidris alpine), Kentish Plover and Marsh Sandpiper (Tringa stagnatilis) in winter. These species accounted for more than 85% of the total shorebirds. The numbers of shorebirds counted was highest in spring and then in autumn, winter and summer respectively. Among the four seasons, there were few significant differences in the number of bird species between the sites outside the seawall (intertidal mudflat) and the sites inside the seawall (artificial wetland), but the average density of shorebirds was obviously different. The habitat-selection analysis of the environmental factors (outside and inside the seawall) impacting on the shorebird community was made in the 10 study sites with Canonical Correspondence Analysis. The study results indicated that: (1) Outside the seawall, the widths of the total intertidal mudflat and bare mudflat were the key factors affecting the shorebirds; the proportion of bulrush (Scirpusmariquete) covering and supertidal mudflat width had a positive correlation with the abundance of birds, while human disturbance and the proportion of both reed (Phragmites communis) and smooth cord-grass (Spartina alterniflora) covering in total surveyed areas had negative impacts on bird numbers; (2) Inside the seawall, the proportions of areas with shallow water and mudflats occupying the total surveyed area were key factors influencing the number of birds; the size of the bulrush area should have a positive impact on the appearance of shorebirds. Habitats with heavy human disturbance, dense reed and smooth cord-grass or a high water level were not conducive to be inhabited by shorebirds.     

长江口杭州湾鸻形目鸟类群落季节变化和生境选择

在长江口南岸杭州湾北岸滨海滩涂进行了鸻形目鸟类的资源调查,以及鸟类栖息地选择模式分析,2004年3月至2005年1月共统计到鸟类25种,春季优势种为大缤鹬(Calidris tenuirostris)、尖尾缤鹬(Calidris alpine)和红颈滨鹬(Calidris ruficollis);夏季为环颈(Charadrius alexandrinus)、青脚鹬(Tringa nebularia)和蒙古沙(Charadrius mongolus),秋季为环颈、红颈滨鹬和青脚鹬,冬季为黑腹滨鹬(Calidris alpina)、环颈和泽鹬(Tringa stagnatilis),鸟类总体数量呈春季>秋季>冬季>夏季,海堤外(自然滩涂)和堤内(人工湿地)鸟类种数四季大致相等,但鸟类平均密度季节差异显著。通过对样点内鸟类与环境因子进行多元分析,初步总结出堤外滩宽和光滩宽是影响鸟类栖息的最关键因子,海三棱草(Scirpus× mariquete)覆盖比例和潮上坪宽度的影响程度次之。堤内浅水塘比例和裸地比例是影响形目鸟类分布的关键因子,海三棱草覆盖比例也起正向作用。而人类干扰大、芦苇(Phragmites communis)/互花米草(Spartina alternifloral)密植和高水位的区域不利于鸟类利用。     

1. BIRD-LIFE AT THE ORANGE RIVER MOUTH

Kalejta, B. 1993. Diets of shorebirds at the Berg River estuary, South Africa: spatial and temporal variation. Ostrich 64: 123–133.

The diets of three common migrant waders; Curlew Sandpiper Calidris ferruginea. Grey Plover Pluvialis-squatarola and Greenshank Tringa nebularia and three resident species, Blacksmith Vanellus armatus, Kittlitz's Charadrius pecuarius and Whitefronted Plovers C. marginatus, were studied at the Berg River estuary, South Africa from December 1987 to April 1989. Direct observations of feeding were combined with analyses of stomach contents, pellets and droppings. Nereid worms, Ceratonereis erythraeensis and C. keiskama, were the principal food of all species studied except Greenshanks, which fed mostly on crabs, Hymenosoma orbiculare. Despite considerable overlap in the diets of all bird species, there were differences in the size classes of nereids taken by different bird species. Visually-foraging plovers (Charadriidae) were highly selective, feeding on the largest nereids regardless of their abundance. Tactile foragers, represented by Curlew Sandpipers, were non-selective, and consumed different size-classes of worms in proportion to their abundance in the substratum. Seasonal variations in the diet of waders are linked to seasonal changes in the availability of prey species.     

长江口滩涂围垦后水鸟群落结构的变化——以南汇东滩为例

近年来长江口滩涂湿地高强度的促淤围垦对生物多样性保育造成了严重影响。本研究于2006至2010年在南汇东滩进行了水鸟调查,研究围垦后堤内环境的快速演替过程对水鸟的群落结构的影响。通过分析鸻鹬类、雁鸭类和鹭类三类主要水鸟类群,结果表明鸻鹬类的总数呈严重下降趋势（ANOVA, p=0.009）,而雁鸭类和鹭类总数在上升（ANOVA,p=0.015;p=0.00）;在种类数量方面,鸻鹬类和雁鸭类差异不显著（ANOVA,p=0.597;p=0.523）,鹭类种类数变化极显著（ANOVA ,p=0.00）。同时,通过对水鸟的栖息地选择因子偏好的分析, 发现滩涂减少是鸻鹬类减少的主要因素,而大型鱼塘和芦苇增加是雁鸭类和鹭类增加的重要原因。为此我们提出相应海岸带湿地管理建议。     

Environmental heterogeneity, spatial segregation of prey, and the utilization of southwest Atlantic mudflats by migratory shorebirds

We studied the relationships between the habitat use of migratory shorebirds and the spatial distributions of the Southwestern Atlantic Fiddler Crab Uca uruguayensis , polychaetes, sediment characteristics and tidal levels in the Río de La Plata estuary, Argentina, where U. uruguayensis is one of the most important intertidal species. Crabs have a well-defined patchy distribution that is segregated spatially from that of polychaetes. Crab density on the surface varied across the tidal cycle, reaching maximum values during low tide. Polychaete density decreased with depth but showed no change through the tidal cycle; however, given that sediment penetrability did change during the same period, their availability to probing shorebirds is expected to change. Habitat use by shorebirds followed the spatial distribution of prey; shorebirds that foraged on polychaetes (White-rumped Sandpiper Calidris fuscicollis , Two-banded Plover Charadrius falklandicus and Hudsonian Godwit Limosa haemastica ) focused their attention on the areas with the highest densities of polychaetes, whereas species that preyed mostly on crabs (Ruddy Turnstone Arenaria interpres , Whimbrel Numenius phaeopus and Grey Plover Pluvialis squatarola ) predominantly used areas with crabs. This segregation occurred particularly during low tide, a period in which polychaetes became fully available. Results show that the spatial and temporal heterogeneity of mudflats in relation to the types and availability of prey has a strong effect on shorebird habitat use.     

金门浯江溪口鸟类的多样性

在福建省金门岛西岸的滨海滩地浯江溪口进行了为期2年的调查,采用每月2次的定点调查,获得鸟类30科105种的记录,2000年为27科89种5514只;2001年为28科84种9079只,两年种类和数量起伏月变动曲线都有2个高峰,一是在春季,另一是在秋季,虽两年高峰点有前后之差,但曲线的模式,基本上是一致的,滩地的冬候鸟和旅鸟最为显著,优势种包括普通鸬鹚（Phalacrocorax carbo),环颈Xing（Charadrius alexandrinus),白腰杓鹬（Numenius arquata),中杓鹬（Numenius phaeopus),翻石鹬（Arenaria interpres),黑腹滨鹬（Calidris alpina)等,物种多样性指数均以春季最高,秋季次之,夏季最为贫瘠。     

Foraging Ecology of Fall-Migrating Shorebirds in the Illinois River Valley

Populations of many shorebird species appear to be declining in North America, and food resources at stopover habitats may limit migratory bird populations. We investigated body condition of, and foraging habitat and diet selection by 4 species of shorebirds in the central Illinois River valley during fall migrations 2007 and 2008 (Killdeer [Charadrius vociferus], Least Sandpiper [Calidris minutilla], Pectoral Sandpiper [Calidris melanotos], and Lesser Yellowlegs [Tringa flavipes]). All species except Killdeer were in good to excellent condition, based on size-corrected body mass and fat scores. Shorebird diets were dominated by invertebrate taxa from Orders Diptera and Coleoptera. Additionally, Isopoda, Hemiptera, Hirudinea, Nematoda, and Cyprinodontiformes contribution to diets varied by shorebird species and year. We evaluated diet and foraging habitat selection by comparing aggregate percent dry mass of food items in shorebird diets and core samples from foraging substrates. Invertebrate abundances at shorebird collection sites and random sites were generally similar, indicating that birds did not select foraging patches within wetlands based on invertebrate abundance. Conversely, we found considerable evidence for selection of some diet items within particular foraging sites, and consistent avoidance of Oligochaeta. We suspect the diet selectivity we observed was a function of overall invertebrate biomass (51.2±4.4 [SE] kg/ha; dry mass) at our study sites, which was greater than estimates reported in most other food selection studies. Diet selectivity in shorebirds may follow tenants of optimal foraging theory; that is, at low food abundances shorebirds forage opportunistically, with the likelihood of selectivity increasing as food availability increases. Nonetheless, relationships between the abundance, availability, and consumption of Oligochaetes for and by waterbirds should be the focus of future research, because estimates of foraging carrying capacity would need to be revised downward if Oligochaetes are truly avoided or unavailable for consumption.     

SITE FIDELITY IN HIGH ARCTIC BREEDING WADERS

Tomkovich, P.S. & Soloviev, M.Yu. 1994. Site fidelity in High Arctic breeding waders. Ostrich 65:174-180.

The return rate and fluctuations in density between years were determined for colour-marked populations of Grey Plover Pluvialis squatarola. Little Stint Calidris minuta, Curlew Sandpiper C. ferruginea, Sanderling C. alba and Knot C. canutus in a study in the Knipovich Bay area, northern Taimyr, Central Siberia (76°05'N. 98°32'E) during three breeding seasons, June 1990 to August 1992. No birds marked as chick were recorded as returning to the study area. Females of all species exhibited low site fidelity. The return rate of males varied between species. No marked male Curlew Sandpiper or Little Stint were recorded in the season following the marking, which is compatible with the nomadic behaviour of these two species. In contrast, males of Grey Plover and Knot were site faithful and had return rates of 78% and 8% respectively (though the latter value may have been underestimated). Site fidelity of Sanderling males lay between these extremes (the return rate was 20%). The variability of bud breeding density in the stud area was negatively correlated with return rate and reached the largest value in Little Stint (a factor 07 18.0 between the lowest and highest densities) and Curlew Sandpiper (factors of 4,4 for males and 5,7 for females), being intermediate in Sanderling (2,5) and the smallest in males of Grey Plover (1,Z) and Knot(1,4).

In the late and cold season of 1992, bird densities were smallest in all ses and the largest proportion of site faithful, but unmated, males of Grey Plover and Knot were recorded. Species with highly opportunistic and comparatively conservative territorial connections can be recognise among Siberian High Arctic waders. All species appear to show some degree of opportunism, which is probably dictated by a number of factors of which climate is the most important.     

Nereidid polychaetes as the major diet of migratory shorebirds on the estuarine tidal flats at Fujimae-higata in Japan

The dietary items of five migratory shorebirds, Dunlin (Calidris alpina), Red-necked Stint (C. ruficollis), Grey Plover (Pluvialis squatarola), Whimbrel (Numenius phaeopus) and Black-headed Gull (Larus ridibundus), were examined by analyses of fecal droppings during the birds' migration or wintering and by surveys of macrobenthic fauna around their foraging sites on the tidal flats of Fujimae-higata, Nagoya, central Japan. Body parts of nereidid, capitellid, and spionid polychaetes and crustaceans were found in fecal droppings from all of these shorebirds. Two nereidid species (Hediste diadroma and Neanthes succinea) with relatively large body sizes seemed to be the majority dietary items. At one site, H. diadroma was dominant in terms of biomass (40-370 g/m(2)) throughout year except, for less than 1 g/m(2) in March and May (within or just after reproduction of this species). Monthly changes in the occurrence of food items in fecal droppings of C. alpina were examined in 1999 and 2000. Most (85-100%) of the fecal droppings contained nereidid body parts, including Hediste-specific simple chaetae from November to April, whereas only 23% of the droppings contained them in May. Chaetae of capitellid or spionid polychaetes were frequently found from January to April (38-86% of droppings). Crustacean body parts, including amphipod appendages, were frequently found from March to May (86-100% of droppings). The relationship between foraging habits of the shorebirds and the life history of their major prey nereidid species is discussed.     

Community composition, seasonal dynamics and interspecific correlation of waterbirds in the Qiantangjiang River estuary and Hangzhou Bay

Waterbird surveys were conducted regularly in the Qiantangjiang River estuary and Hangzhou Bay from July 2007 to November 2011. A total of 128 species (nine orders and 18 families) were recorded, including 119 migrants which accounted for 93% of the total species; eleven species were listed as National Protected Species. Inter-specific correlation analysis for 13 shorebird populations and nine duck populations recorded over time found that 21 pairs of shorebirds and 23 pairs of ducks were correlated. By looking at seasonal dynamics and migration patterns we were able to divide the migration process into six stages: (1) late July to late September was the migration peak of shorebirds, which were dominated by Limosa limosa, Calidris ruficollis and Charadrius mongolus. (2) Early October to mid-December was the migration peak of wintering migrants of shorebirds and ducks, which were the first two large groups in our study areas. (3) Late December to mid-February was the wintering period of migration waterbirds. (4) Late February to late March was the peak migration of ducks and the winter migrants of shorebirds dominated by Calidris alpina. (5) Early April to mid-May was the migration peak of passage migrants such as, Calidris ruficollis, Calidris acuminate and Limosa limosa but the population size of shorebird winter migrants dominated by Calidris alpine was still larger than the former. (6) Late May to mid-July was the breeding season of all egrets, summer migrants of gulls and several species of shorebirds. Our surveys show that interaction among species is possibly an important determinant of community composition of shorebirds and wintering ducks during the migration season. It may be the geographical position and community composition of migrant shorebirds across Hangzhou Bay that mean during the northward migration there are far more shorebirds than during the southward migration.     

盐地碱蓬盐沼与相邻泥质滩涂湿地迁徙期鸻鹬类的群落组成及行为差异

盐地碱蓬(Suaeda salsa)盐沼湿地是黄渤海地区河口区域的重要湿地类型, 是水鸟迁徙停歇期的重要栖息地。本研究以辽河口国家级自然保护区为研究地点, 通过对盐地碱蓬盐沼湿地和相邻泥质滩涂两个固定样区连续三年的水鸟组成调查和行为观察, 分析盐地碱蓬盐沼湿地在鸻鹬类多样性维持和栖息地利用中的作用。共记录到鸻鹬类水鸟28种6,348只次, 其中盐地碱蓬湿地记录到4科13种, 泥质滩涂记录到4科27种, 泥质滩涂的物种多样性显著高于盐地碱蓬盐沼湿地。此外, 盐地碱蓬盐沼湿地与相邻的泥质滩涂的鸻鹬类鸟类群落组成存在较大差异, 盐地碱蓬盐沼湿地的鸟类群落组成以体型较大的大杓鹬(Numenius madagascariensis)、白腰杓鹬(N. arquata)、灰鸻(Pluvialis squatarola)等为主, 而泥质滩涂以环颈鸻(Charadrius alexandrinus)、黑腹滨鹬(Calidris alpina)等小型鸻鹬类为主, 这说明两种生境在鸟类多样性维持中具有不同的功能。行为分析发现, 泥质滩涂中栖息鸟类的主要行为为取食(58.71%-93.26%), 而盐地碱蓬盐沼湿地鸟类的行为既包括较大比例的取食, 也包括休息, 特别是在春季迁徙期。这进一步说明, 两种生境在水鸟的栖息地利用中具有一定的生态功能差异。尽管盐地碱蓬盐沼湿地记录到的鸟类物种数和数量均低于泥质滩涂, 但是, 两种生境中存在较大比例的共同分布物种, 这说明其生态功能具有较强的生态互补性, 二者作为一种独特的湿地景观组合, 在鸻鹬类迁徙停歇期的栖息地利用和物种多样性维持中发挥着不可替代的作用。     

辽宁鸟类分布新记录4种：小滨鹬、 长嘴半蹼鹬、斑胸滨鹬、流苏鹬

2010年至2019年间,鸟类研究者和观鸟爱好者在辽宁鸭绿江口和辽河口湿地累计记录到鸻形目（Charadriiformes）水鸟48种,其中小滨鹬（Calidris minuta）、长嘴半蹼鹬（Limnodromus scolopaceus）、斑胸滨鹬（C. melanotos）、流苏鹬（C. pugnax）等4种是辽宁省鸟类分布新记录种。     

Migrant shorebird use of Akimiski Island, Nunavut: a sub-arctic staging site

Determining the importance of stopover and staging areas to migrating shorebirds (Aves: Charadriiformes) is essential if such habitats are to be successfully protected. Migration chronology, species composition, length of stay, body condition, and estimated total abundance of shorebirds during spring and fall migratory periods of 2008 and 2009 were documented on Akimiski Island, Nunavut, Canada. Fourteen shorebird species were observed during spring point counts and 18 during fall. Semipalmated (Calidris pusilla) and White-rumped (C. fuscicollis) Sandpipers comprised about 80?% of all individuals observed. A greater number of species and individuals were observed during fall than spring in both years. Radio-transmitters attached to juvenile Semipalmated and Least (C. minutilla) Sandpipers indicated highly variable lengths of stay ranging up to 26?days in both species (Semipalmated Sandpiper averaged 6.5?±?2.67?days, n?=?12; Least Sandpipers averaged 7.25?±?3.79?days, n?=?8). In 2009, Semipalmated Sandpipers captured and weighed later in the season were significantly heavier than those captured earlier suggesting that this species is refueling while on Akimiski Island. A fall migration seasonal density of 5,267 (2,193–8,341) shorebirds/km² was estimated given a residence probability (i.e., the probability of an individual being present in consecutive counts) of 0.906?±?0.181. Assuming similar habitat value and shorebird density, an extrapolation of the seasonal plot density of 5,267 birds/km² to the total 192?km² mudflat habitat on Akimiski Island yields an estimate of 1,011,264 (421,098–1,601,429) shorebirds during fall migration, making Akimiski Island of Hemispheric importance as a staging site for migrant arctic-breeding shorebirds.     

Genetic structure among Charadrius plovers on the African mainland and islands of Madagascar and St Helena

Colonization of islands by long-distance dispersers has great impact on genetic diversification among populations and may spearhead speciation events. We investigated intra- and interspecific divergence in Charadrius plovers with populations on mainland Africa, Madagascar and St Helena. We analysed microsatellite loci and sequence data from four nuclear and two mitochondrial gene regions. Charadrius plovers are shorebirds with high dispersal and mobility. Our results confirmed genetic differentiation between Madagascar and mainland populations of three plover species (White-fronted Plover Charadrius marginatus, Kittlitz's Plover Charadrius pecuarius and, based on sequence data only, Three-banded Plover Charadrius tricollaris) but highlight substantial variation in levels of intraspecific divergence among the three species. Namely, the Kittlitz's Plover, a dispersive habitat generalist with a polygamous mating system, exhibited lower island–mainland differentiation (0.05% COI sequence divergence) compared with the two monogamous species, the White-fronted Plover (0.6% COI divergence) and Three-banded Plover (1.6% COI divergence). In addition, past colonization of the islands of St Helena and Madagascar by ancestors of today's Kittlitz's Plover has led to the evolution of two endemic island species, the Madagascar Plover Charadrius thoracicus and the more closely-related St Helena Plover Charadrius sanctaehelenae. We discuss the factors driving species differences in island–mainland divergence and highlight the importance of conserving genetically unique island populations and island habitats to safeguard future evolutionary potential.     

Breeding dispersal and site-fidelity in three monogamous wader species in the Western Isles, U.K.

Adult and post-natal breeding-dispersal movements of Redshank Tringa totanus , Dunlin Calidris alpina and Ringed Plover Charadrius hiaticula were quantified in west Scotland. Data from 373 returning birds marked as breeding adults and 142 returning birds marked as chicks are presented. Unlike most previous studies, this study measured dispersal movements up to 40 km and attempted to overcome distance-related biases. For each species, adult males were significantly more nest site-faithful between years than were adult females. Likewise, first-time breeding males bred significantly closer to their natal site than did females. The settlement intensity per unit area of habitat showed marked differences between species, age classes and sex in the relative attractiveness of potential areas at different distances to settling birds. Adult dispersal was negatively and significantly related to breeding success in the previous year and positively related to capture on the nest in the previous year. Dispersal movements of adult Ringed Plover breeding on unstable cultivated habitats were significantly related to habitat quality (measured in terms of nest survival) and were always to habitat of better or equal quality.     

Variability in the area,energy and time costs of wintering waders responding to disturbance

Birds’ responses to human disturbance are interesting due to their similarities to anti‐predator behaviour, and understanding this behaviour has practical applications for conservation management by informing measures such as buffer zones to protect priority species. To understand better the costs of disturbance and whether it will impact on population size, studies should quantify time‐related responses as well as the more commonly reported flight initiation distance (FID). Using waders wintering on an estuarine area, we experimentally disturbed foraging birds on the Wash Embayment, UK, by walking towards them and recording their responses (FID, alert time, time spent in flight, time taken to resume feeding, and total feeding time lost). We present data for 10 species of conservation concern: Curlew Numenius arquata, Oystercatcher Haematopus ostralegus, Bar‐tailed Godwit Limosa lapponica, Grey Plover Pluvialis squatarola, Redshank Tringa totanus, Knot Calidris canutus, Turnstone Arenaria interpres, Ringed Plover Charadrius hiaticula, Sanderling Calidris alba and Dunlin Calidris alpina. Larger species responded more strongly, response magnitude was greater under milder environmental conditions, and responses varied over both small and large spatial scales. The energetic costs of individual responses, however, were low relative to daily requirements and disturbance events were unlikely to be frequent enough to seriously limit foraging time. We suggest, therefore, that wintering wader populations on the Wash are not currently significantly negatively impacted by human disturbance during the intertidal foraging period. This is also likely to be the case at other estuarine sites with comparable access levels, visitor patterns, invertebrate food availability and environmental conditions.     

Associations between distance to forest and spatial and temporal variation in abundance of key peatland breeding bird species

Capsule Negative forest edge effects were detected for Willow Ptarmigan (Red Grouse) Lagopus lagopus and Dunlin Calidris alpina.

Aims To investigate the effects of distance to forest on the abundance and changes in abundance of four key peatland breeding bird species, and to measure changes in predatory bird numbers, in the peatlands of northern Scotland.

Methods Bird surveys were carried out in 2000 at 34 plots, covering 197 km² of peatland, and 80 forestry point‐count sites, first surveyed in 1988. Habitat data were also collected in 2000. We used multi‐model inference to investigate the associations between forest distance and other habitat variables, and the abundance, and changes in abundance, of four bird species of economic or conservation importance: Red Grouse, European Golden Plover Pluvialis apricaria, Dunlin and Common Greenshank Tringa nebularia.

Results There was strong evidence that distance to forest was negatively associated with Dunlin abundance and changes in Red Grouse abundance, but only weak evidence for negative associations with Golden Plover abundance and changes in Dunlin abundance. There was no evidence of a forest distance effect on Greenshank. Among predatory birds, there were no significant increases either on peatland plots or in new forestry plantations.

Conclusions This study provides evidence that, for a given habitat quality, Dunlin densities are lower, and Red Grouse declines more likely, near to forest edges, but weak evidence only that Dunlin declines are more likely, and Golden Plover abundance lower, near to forests. These results suggest that for at least two key peatland breeding birds, forest removal is likely to benefit birds breeding on adjacent unafforested peatland.     

Use of wetlands at the mouth of the Yangtze River by shorebirds during spring and fall migration

ABSTRACT.   The mouth of the Yangtze River is an important stopover site for migratory shorebirds using the East Asian-Australasian Flyway. From 1984 to 2004, we censused and banded shorebirds and monitored hunting activities at the mouth of the Yangtze River to understand how shorebirds used the study area. Counts and banding data revealed greater numbers of shorebirds at the mouth of the Yangtze River during northward migration (spring) than during southward migration (fall), with ratios varying from 1.5:1 to 7.2:1 at different sites from 1984 to 2005. The most common species observed during spring (northward) migration were Great Knots ( Calidris tenuirostris ), Red Knots ( Calidris canutus ), Bar-tailed Godwits ( Limosa lapponica ), Sharp-tailed Sandpipers ( Calidris acuminata ), and Red-necked Stints ( Calidris ruficollis ). During spring 2003–2004, 96.98% of the shorebirds observed were adults (ASY or older) and 3% were after hatching-year and second-year birds (AHY or SY). In contrast, almost all (94.73%) birds counted during the fall were hatching-year (HY) birds. These results indicate that adult shorebirds either use a different migration route during fall migration or use the same route, but do not stop at the mouth of the Yangtze River. HY birds, however, may depend on the coastal stopover sites for feeding during their first southward passage.     

青海湖鸻鹬类群落特征和时空分布

于2006年至2009年间对环青海湖鸻鹬类的群落特征和时空分布进行了资源调查,以期对青海湖保护管理提供科学依据。根据青海湖的地形、植被和水系分布以及水鸟聚集特点,环青海湖选择了15个调查地点,采用直接计数法进行了14次调查,并应用Shannon-wiener指数进行了多样性分析。共记录到鸻鹬类4科28种。数量上红脚鹬(Tringa totanus)、环颈鸻(Charadrius alexandrinus)和黑尾塍鹬(Limosa limosa)是当地的主要物种,分别占鸻鹬类调查总数的33.3%、22.0%和16.2%。分布上环颈鸻最为广泛,在各调查地点均有发现,其次为红脚鹬、黑尾塍鹬和青脚滨鹬(Calidris temminckii),分布地点达10处以上。黑马河和布哈河口多样性较高,这与其适宜的河漫滩和沼泽等栖息环境以及丰富的食物有关。季节上8~10月多样性较高,其次是4~5月。青海湖鸻鹬类的数量高峰依次为10月、8月和5月,物种数高峰为8月和4月,并且秋季物种数高于春季。主要物种红脚鹬和环颈鸻的迁徙动态较为一致,均是8月份达到全年数量最高值,次高峰为5月和10月;黑尾塍鹬的数量在10月份达到全年最高峰。青海湖鸻鹬类迁徙时间与渤海湾较为一致,这可能与历史上长期形成的迁徙模式有关。鄱阳湖和洞庭湖的鸻鹬类主要物种与青海湖比较接近,但数量远远多于青海湖。近年来,游客和游船等人为活动的增加导致青海湖产生局部污染,因此应重视环青海湖生态环境的保护管理,减少对鸻鹬类等水鸟栖息地的人为干扰。