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Many migratory shorebird species using the East Asian–Australasian Flyway are declining rapidly. While the loss of staging habitats in East Asia is considered the primary cause, stressors to fitness often occur throughout the geographic range of declining species, and threats in the non-breeding grounds have been comparatively poorly studied. Three species of migratory shorebird, Curlew Sandpiper (Calidris ferruginea), Sharp-tailed Sandpiper (C. acuminata) and Red-necked Stint (C. ruficollis), use Australia’s dynamic temporary wetland systems opportunistically, yet these large wetland systems have become increasingly degraded, with reduced frequency and extent of flooding. Here, we test whether variables related to wetland availability in Australia’s interior can explain annual variation in apparent survival, abundance or immature to adult ratios at three well-monitored coastal shorebird areas in southern Australia (total area > 1315 km2). We show that coastal annual bird abundance and ratios of immatures at the coast were higher when inland Australia was relatively hot and dry. Also, a small but significant amount of variation in annual apparent survival can be explained by annual variation in inland conditions, with higher survival rates in years when inland conditions were relatively wet and cool. For the endangered Curlew Sandpiper, the impacts of Australian environmental conditions may be exacerbating the impacts of conditions experienced in other parts of its range on fitness and survival. While the effects we document here are relatively weak, they do suggest that management of inland wetlands for these shorebirds may positively affect survival rates of these sharply declining species.

Vanausdall RA, Dinsmore SJ. 2021. Stopover ecology of the least sandpiper (Calidris minutilla) in Iowa: implications for reservoir management. Lake Reserv Manage. 37:300–312.Multipurpose reservoirs...

We report the mitochondrial genome sequences of two migratory shorebirds, the Hudsonian godwit (Limosa haemastica) and the Red knot (Calidris canutus) obtained through shotgun sequencing. The mitogenome is of 16.445 bp for the godwit and 15.609 bp for the knot containing thirteen protein-coding genes, two rRNAs, twenty-two tRNAs, and a control region. The ATP8 and tRNA-Glu were not found in the knot. Bayesian phylogenetic analysis supported the position of both species in the clade of the Scolopacidae Family.

Each year, thousands of Nearctic shorebirds migrate from breeding grounds in the northern hemisphere to wintering grounds in South America. At the wintering sites, in addition to moulting their flight feathers and plumage, shorebirds engage in feeding to increase body mass to gain sufficient energy for the return migration to the breeding grounds. This study aims to describe the temporal variation of body mass and plumage of the Semipalmated Plover (Charadrius semipalmatus), Spotted Sandpiper (Actitis macularius), Sanderling (Calidris alba) and Semipalmated Sandpiper (Calidris pusilla) during the wintering season on the north-eastern coast of Brazil and to evaluate the relationship between mass gain and plumage moulting. The lowest average masses for each of these species were recorded in October, November, December and January, usually when displaying non-breeding plumage. Shorebirds with intermediate and breeding plumage were frequently recorded in the migration preparation period beginning in April, with a significant increase in body mass. However, for some individuals low masses were recorded late during the wintering period and these were all found to be actively moulting. The highest values for body mass were recorded for shorebirds with breeding and intermediate plumage that were not actively moulting, nearing the end of wintering period.

A single individual of feather mite Alloptes (Conuralloptes) calidridis Dubinin, 1951 is reported from the covert feathers of a juvenile Dunlin Calidris alpina Linnaeus, 1758. A redescription of a ...

Worldwide, most populations of migratory shorebirds are in jeopardy, none more so than those of the East Asian–Australasian Flyway (EAAF). In order to preserve these highly mobile species a detailed understanding of their use of feeding and resting sites along the flyway is required. In this study we used light-level geolocators and new analytical tools to reveal individual breeding locations and migration routes of 13 Sanderlings (Calidris alba) that spend their non-breeding season in South Australia. We then used these individual migration routes to identify the timing and location of important stopping areas and compared this with assessments based on resightings of leg-flagged birds and count data. During both northward and southward migration, Sanderlings were found to make extensive use of five main areas of the Chinese coastline, the Yellow Sea and the northern end of the Sakhalin Peninsula. Insights gained from the individual migration routes highlight inherent biases in using only count and resighting data to identify important feeding and resting sites along the Flyway. These findings suggest that data on individual movements may be crucial to effective conservation planning of shorebirds in the EAAF and elsewhere in the world.

Many long-distance migratory shorebirds are threatened. Anthropogenic disturbance at roost sites on their non-breeding grounds might exacerbate other threats by leading to depletion of fat reserves and forcing birds away from traditional sites. We measured the response (occurrence of alarm flight and resettlement time) of roosting shorebirds knots (Calidris spp.) and sand plovers (Charadrius spp.) to anthropogenic and natural disturbances. Flight was the most common response (0.86 alarm flights h–1). The likelihood of an alarm flight was most strongly influenced by flock size and distance to the disturbance agent, smaller flocks closer to the agent being more likely to take flight. Sand plovers had shorter flight-initiation distances than knots but took longer to resettle after disturbance. Resettling duration was also influenced by time since arrival on the non-breeding grounds, being longest shortly after birds arrived. Energy budget models suggested that 10 alarm flights per day increased daily energy expenditure by 4.5–4.7% for knots and 7.5–7.8% for sand plovers. This may reduce energy reserves to levels below the threshold that can be replenished by normal intake rates and thus negatively affect survival or reproductive success. Increased disturbances may place additional and unsustainable pressures on populations that are already experiencing major declines.

Capsule Context-specific equations are needed to reconstruct diet composition and intake rate of Red Knots by the use of shell fragments retrieved from droppings.Aims To explore whether the method to reconstruct Red Knot diet described by Dekinga & Piersma [Dekinga, A. & Piersma, T. 1993. Reconstructing diet composition on the basis of faeces in a mollusc-eating wader, the Knot Calidris canutus. Bird Study 40: 144-156] accurately predicts the diet of Red Knots Calidris canutus canutus outside Northwest Europe, at Banc d'Arguin, Mauritania.Methods Feeding experiments with captive Red Knots on the bivalves Dosinia isocardia or Loripes lucinalis were carried out at Banc d'Arguin, the main wintering area of Red Knot subspecies C. c. canutus. Ingested diets were compared with the reconstructed diets derived from the general method developed by Dekinga & Piersma (1993). Droppings collected over multiple years were also analysed to evaluate the calibration method from this study.Results Of the total ingested shell mass (DMshell) in both bivalves, approximately 65% of the shell mass was retrieved in the droppings (DMdrop). Therefore, dry mass of droppings in the field (DMdrop) has to be multiplied by 1.547 to calculate the ingested dry mass (DMshell). For size estimations of ingested shells from droppings, hinges should be used for D. isocardia and hinges including tops for L. lucinalis.Conclusion The correction factor of 1.547 found here is 50% larger than the factor 0.993 for heterodont bivalves from Europe established by Dekinga & Piersma (1993). Application of the published factor would lead to serious underestimation of energy intake rates based on dropping frequencies and dropping content (by as much as 35%), although it would have small effects on the relative species composition of the diet. Having shown that such correction factors can differ among sites and prey we recommend their determination in new ecological contexts.

Brain lateralisation in animals with laterally placed eyes often leads to preferential eye use for ecologically relevant tasks such as monitoring predators and companions. Few studies of preferential eye use have been conducted in the wild and it is not clear if such preferences in the wild are widespread, how individuals can benefit from them, and which ecological factors influence their evolution. In a wild species of bird the extent to which foraging success varied depending on which eye is used during concomitant anti-predator vigilance was examined. When foraging in open mudflats, semipalmated sandpipers (Calidris pusilla) are frequently exposed to predation attempts by falcons (Falco spp) that originate from the tree cover bordering mudflats. Sandpipers spread along the receding tideline and can face the riskier side of their habitat primarily with the left or the right eye as they forage. If foraging is mostly incompatible with vigilance, the rate at which prey items are collected should decrease when birds use their less-preferred eye to scan cover. If foraging and vigilance can be carried out simultaneously, time spent foraging should not be affected but the efficiency with which their burrowing amphipod prey are located may be reduced, thus leading to decreased capture rate. Birds facing the riskier side of the habitat with their right eye captured significantly more prey than those scanning the same side with their left eye. Specialised eye use in sandpipers may allow individuals to perform simultaneous tasks, such as foraging and vigilance, more efficiently.

Mangrove habitats are host to many waterbirds around the globe. However, the roles of mangrove habitat structures in association with variation in individuals and their community of waterbirds have not been examined in detail. The objective of this study was to determine the abundance, diversity and evenness of waterbirds in an Avicennia mangrove habitat. The study was conducted using a point count method at Hara Protected Area (HPA) in Iran for 1 year. A total of 59,387 waterbirds observations, belonging to 56 species, were recorded and categorized based on different seasons, where 13,825 (49 spp.), 34,267 (54 spp.), 6939 (46 spp.) and 4356 (35 spp.) observations were recorded in the different seasons of fall, winter, spring and summer respectively. In total, 80.98% of individual observations had occurred during the migratory season. Dromas ardeola (11,329 observation; 19.08%) and Calidris alpina (5261 observation; 8.86%) were the most abundant, while three species including Phalacrocorax nigrogularis (4...

Biometrics of Purple Sandpipers captured in Brittany, northern France, indicated that they belonged to a long-billed population, so may have originated in Canada or Russia. There was a preponderance of males (81%). An uneven sex ratio in favour of males is proving to be the norm for winter populations of Purple Sandpiper. A high percentage of captures were of first-year birds. This was probably biased by the catching methods (mist-netting and dazzle-netting), because a lower value was obtained by observing free-living birds.

Capsule The uneven sex ratio in favour of males found in flocks of Purple Sandpipers is not evident in chicks; female chicks are lighter than males. Aims To test if there is an uneven sex ratio at hatching and to investigate whether sex ratio changes during chick growth and after fledging. Methods Sex of chicks was determined (by DNA) and each chick given a unique combination of colour‐rings for later re‐sightings. Biometric measurements were made for comparisons between the sexes. Results The sex ratio of 97 chicks did not deviate significantly from parity, 52.6% males (95% CI: 42.2–62.8%), and there was no evidence that the sex ratio changed as chicks grew older. However, sightings of colour‐ringed birds in their first year indicated a change to 61% males. The same sex ratio (61% males) was observed among wintering birds in Iceland. Chicks already showed sexual size dimorphism in skeletal measurements as is also found in full‐grown birds. Female chicks were relatively lighter than males, suggesting poor...

Capsule Iceland is a stop‐over site for a population of Purple Sandpipers that winter in Britain. Here, they accumulate fuel loads for onward migration along with birds that have wintered in Iceland. Aims To establish whether Purple Sandpipers from Britain stop‐over in Iceland during spring migration and, if so, to describe their population structure, changes in mass and moult. Methods Purple Sandpipers were cannon‐netted on the coast of the Reykjanes Peninsula in southwest Iceland during May 2003 and 2005. Birds were aged, sexed (some by DNA) and standard biometric measurements made. Active body moult was scored. Results Bill and wing lengths showed that the Purple Sandpipers we caught were similar to one of the populations that winter in Britain rather than Icelandic breeding birds. There were more males than females throughout the migration period (63% males for first‐year‐birds and 67% for adult birds). Accounting for a bias due to a higher percentage of males in a less usual habitat (muddy/sandy bays...

Wintering Purple Sandpipers Calidris maritima were captured at Varangerfjorden, Finnmark, in March 1992, and compared with samples from Troms county in November 1988 to describe the population structure in north Norway in terms of age and sex classes, and to determine the origins of these wintering birds. The overall percentage of first‐year birds was 35% at Varangerfjorden, higher than that in Troms (21%). However, there may have been biases in the catches at Varangerfjorden, and the percentage in the largest catch was 23% first‐year. In both regions, the percentage of first‐year birds varied among sites, indicating age segregation. There was a higher percentage of males than females in the first‐year population at Varangerfjorden and in both age classes at Troms. The wing and bill lengths of the different age/sex classes at Varangerfjorden and Troms were similar, indicating largely similar origins. Comparison of bill and wing lengths of wintering birds with samples from the breeding grounds supports res...

Capsule Breeding wader populations have more often shown declines than passerine populations during the last 10–20 years. Aims To determine abundance changes in British upland breeding birds during the last 10–20 years. Methods We re-surveyed 1348 km2, in nine study areas, of the British uplands in 2000 and 2002, which had been previously surveyed between 1980 and 1991. In addition, we included data from recent repeat surveys in four other upland areas, covering approximately 365 km2, to broaden the scope of our study. Results We found evidence of widespread population declines in three species of breeding waders, Lapwing Vanellus vanellus, Dunlin Calidris alpina and Curlew Numenius arquata. Among the passerines, some species declined, including Twite Carduelis flavirostris and Ring Ouzel Turdus torquatus, while others showed strong gains, including Stonechat Saxicola torquata and Raven Corvus corax. Conclusion Overall, abundance changes were characterized by a high degree of variability across study area...

Capsule Variation in numbers needs to be assessed at both site- and species-specific levels, but low tide counts are representative of average usage in most cases. Aims To determine whether the numbers of waterbirds using six intertidal sites changed across the tidal cycle, how frequently counts were needed to detect change and whether low tide counts were representative of the average numbers using a site. Methods Hourly counts of Shelduck Tadorna tadorna, Wigeon Anas penelope, Oystercatcher Haematopus ostralegus, Dunlin Calidris alpina, Curlew Numenius arquata and Redshank Tringa totanus from six intertidal study sites – in Wales and Cumbria – were analysed using generalized linear models. Results Tidal state was significant in explaining the variation in species' numbers in 20 of 32 cases considered. The relative distribution of birds within one site changed across the tidal cycle for three of four species. In the 12 instances where numbers did not vary tidally, there would be no need to count birds mo...

This paper reports my observations during 1994–97 for both American Samoa and [W] Samoa. New waders added to the Samoan list are Wood Sandpiper (Tringa hypoleucos), Red-necked Stint (Calidris ruficollis), and Red Knot (Calidris canutus). The new breeding records are for the Black-naped tern (Sterna sumatrana), Bridled Tern (Sterna anaethetus), the Common Noddy (Anous stolidus), Crimson-crowned Fruit Dove (Ptilinopus porphyraceus) and the Red-headed Parrot-finch (Erythura cyaneovirens), in Samoa. Crested terns (Sterna bergii), Brown Boobies (Sula leucogaster) and Fairy Terns (Sterna nereis) were also observed with juveniles and so must be regarded as possible breeders in one of the Samoas.

Purple Sandpipers wintering on the Kincardine coast had a protracted autumn arrival (one-quarter and three-quarters of the birds arrived on 30 July and 21 October respectively, 83 days) but a faster spring departure (one-quarter and three-quarters departed on 9 April and 27 May respectively, 48 days). The long arrival period was partly due to differences in the migration phenology of the two main wintering populations: short-billed birds from Norway arrived before the long-billed birds, probably from Canada. There was a smaller difference in departure times of the two populations: short-billed birds left before the long-billed birds. Minimum annual survival was estimated from resightings of 92 marked birds. There was no evidence that survival differed between adults and first-years or between birds of different bill-size classes, which were of different sex and geographical origin. Minimum annual survival was estimated to be 79.5%(se = 2.8%). The similarity between the mortality rate (20.5%) and the perce...

A recent study of the dispersal of wader species using ringing data from the Wash, modelled the movements of three estuarine species. Using similar methods, the movements of Turnstone Arenaria interpres along the North Wales coast are modelled to provide a rocky shore comparison. Survival rates are also estimated, and shown to be similar to other studies, at 86%. The degree of exchange between Turnstone roosts was strongly influenced by distance, with very little movement between roosts more than 3km apart. Compared to results from the Wash, the modelled dispersal of Turnstones was similar to that of Grey Plover Pluvialis squatarola and Dunlin Calidris alpina, but less than Redshank Tringa totanus, although Turnstones appear to show the most rapid decline in capture probability with distance.

Regional trends in the populations of waders wintering largely on estuaries were analysed using data collected by the Wetland Bird Survey between the winters of 1969/70 and 1995/96 to assess whether trends seen at the national level were repeated across regions of Britain. Not all were. Over this period, the numbers of seven of the 12 species studied increased in south and southeast England, but remained static or declined in southwest England and south Wales. Possible explanations for this are proposed. Increases in the number of Curlews Numenius arquata in the north and northeast of Scotland occurred after 1981/82, when the species stopped being a legal quarry species. A rapid decline in Oystercatcher Haematopus ostralegus and Knot Calidris canutus numbers in east England after 1988/89 may be linked to a change in the Wash shell-fisheries. Warmer winters may be making it less essential for birds to winter in the milder west of Britain. In two pairs of regions, northeast and southeast Scotland, and in no...

Little is known about the biology of waders wintering in southern Asia; this paper deals with the Grey Plover Pluvialis squatarola, a species extensively studied only in western Europe. Adult Grey Plovers wintering in southeastern India underwent primary moult in autumn; the duration was estimated to be 127 days, with mean starting date 1 September and mean completion date 5 January. Some first-year Grey Plovers initiated primary moult in late winter and spring, and completed this moult the following spring. The average mass of adults on arrival in September was 200 g, fluctuated close to 220 g from October to February, and increased to 280 g near the end of May. The mass variation did not show the January peak observed in western Europe. Breeding productivity, measured as the percentage of first-year birds in winter catches, varied between 5% and 70% over six years, and showed a positive correlation with that of Dark-bellied Brent Geese Branta b. bernicla in western Europe and Curlew Sandpipers Calidris ...

There are two populations of Purple Sandpipers in Orkney; ‘long‐billed’ birds, which predominate, and ‘short‐billed’ birds. They arrived mainly during October and November, and departed in April and May from sites on Mainland and South Ronaldsay. On Sanday, densities were as high in April as in winter, and peak numbers occurred in early May, suggesting that this island is used for pre‐migratory fattening. The percentage of first‐year birds on Mainland varied annually between 5.8% and 30.5%. The mean mass in winter was relatively stable, between 67 and 71g. A change in population structure in terms of sex ratio and the ratio of ‘short‐billed’ to ‘long‐billed’ birds in May suggested that the two populations or sexes have different migration strategies. Ringing recoveries showed that birds wintering on North Sea coasts migrate through Orkney in May, joining birds which were resident over the winter. Purple Sandpipers increased in mass during May to a mean peak of ca. 90g in mid‐May. The accumulation of fat f...

Dunlin migration in northeast Italy is described. An attempt to identify the main routes and staging areas used by birds wintering in the central Mediterranean is presented. The results of monthly counts from 1990–1995 revealed that the bulk of the population occupied the wintering area in October and left for the breeding grounds in April and May. The analysis of 342 Italian recoveries of foreign ringed birds showed that 65% were ringed during post-breeding migration through the Baltic Sea, whereas just a few birds had been ringed in western Europe. First-year birds arrived in autumn with a single migratory wave, peaking in October. Two categories of adults were identified during post-breeding migration: birds which directly reached Italian wintering sites and birds which arrived after they had suspended their migration for moulting: the Azov/Black Sea wetlands are suggested as possible moulting areas. Out of 2444 adults and 1627 first-years ringed between 1989 and 1996 at our study area, we obtained a t...

The minimum annual survival of Purple Sandpipers as derived from resighting rates in a colour‐ringed population at Helgoland (SE North Sea) was higher in adults (80%) than in first‐year birds (36%). In both first‐year and adult birds, the minimum survival during four winter months (60% and 84%, respectively) was slightly lower than during the eight months from spring to autumn arrival (63% and 85%, respectively). The high winter survival (100%) and low summer survival (64%) of second‐year birds is discussed in relation to different levels of experience in the wintering and first breeding, respectively. Although dispersal to other wintering sites cannot be totally excluded, the disappearance of individuals can generally be attributed to predation (by Sparrowhaioks Accipiter nisus, feral cats). Within Helgoland, a high fidelity to feeding sites and night roosts was recorded.

Growth of mass and linear body dimensions (bill, tarsus and wing length) was studied in the Little Stint Calidris minuta at several locations on the Taimyr Peninsula, Siberia (73°–76°N) in 1983–94. Little Stints fledged at near-adult body mass, at 15 days of age. Growth followed an S-shaped pattern which was best described mathematically by a logistic curve. Curves of this type showed that growth was similar between study sites and years, although there were differences in mass development during the first days after hatching, perhaps related to weather conditions. When the logistic growth curve was used, K L (the standard measure of maximum growth rate) was 0.285. Conversion of this parameter to another S-shaped curve, the Gompertz curve which has been widely used to describe wader chick growth, yields K G = 0.194. This is higher than predicted from an allometric relationship based on 15 other precocial wader species, and might be related to the Little Stint's high latitude breeding range.

Previous studies have shown a relationship between the number of Dunlin breeding on moorland sites in Caithness and Sutherland and the near-infrared reflectance of the sites measured from satellite imagery. We test the generality of this relationship using two images of Caithness and Sutherland recorded 12 years apart, and new imagery and survey data from the Shetland Islands. The correlation between Dunlin abundance and near-infrared reflectance is similar using both images of Caithness and Sutherland but no correlation is apparent in Shetland. This regional difference is explained by relating the spectral characteristics of sites in both study areas to ground cover data recorded from field surveys.

The winter site-fidelity and annual survival of Turnstones Arenaria interpres and Purple Sandpipers Calidris maritima was investigated at Hartlepool, Cleveland using samples of individually colour-ringed birds. All colour-ringed Purple Sandpipers and a high proportion of colour-ringed Turnstones present at the start of winter were resident in the study area throughout the winter. All Purple Sandpipers and a high proportion of Turnstones (81–88%) survived the winter. Reasons for the high winter survival rates of both species in comparison with other waders are discussed. Most Turnstones (83–88%) survived between spring and autumn and came back to Hartlepool, usually to the same feeding area. A lower proportion of Purple Sandpipers (57–77%) survived through the summer to return to Hartlepool, particularly in 1993; some returned to winter elsewhere. Annual survival and summer return rates of both species are discussed in comparison to those reported in previous studies.

Six sites around Borup Fiord, west central Ellesmere Island, Canada, were surveyed for breeding Knot Calidris canutus islandica. Breeding density at the main study site was estimated using a calculation based on hatching success, brood counts and the probability of broods being resighted: estimates from other sites were based on this assessment. Density at the main study site was 4.6 pairs/km2, varying between 0.4 and 12.7 pairs/km2 in different areas. Density was negatively correlated with spring snow cover. At other sites density estimates ranged from nil to 5.7 pairs/km2. Brood counts and registrations of territorial activity accounted for only 33% and 67% of pairs, respectively. A literature review suggested that within the Knot's breeding range, densities appear to be highest in areas showing a warm regional climate, early snow-melt, and high vegetational diversity and density. The Knot's dependence on such areas may be related to its size and need for an early start to breeding. The total breeding p...

The object of the research reported here was to produce a map of habitat quality for the Dunlin across the Flow Country of northern Scotland for use in conservation and land-use planning. The region is too large (ca. 1800 km2) to survey on foot without significant expenditure of time and resources. Habitat quality was therefore predicted by relating Dunlin density recorded on a set of sample sites in the region to vegetation and landform characteristics. Density was then extrapolated across the whole region based on the recurrence of similar habitat conditions. The abundance of Dunlin in the Flow Country is shown to be related to several different classes of environmental variation. Dunlin are absent from several easily delimited types of habitat (e.g. lochs and woodland). A presence/absence map of habitat quality for the species is achieved simply by mapping these habitat features. Abundance on the moorland that remains is related to vegetation characteristics and the presence of clusters of pools (pool-...

Records of Red Knot Calidris canutus in the Middle East are listed and analysed in the light of former perceptions of its status. Special reference is made to its status in Turkey, from where most recent records come. The species is probably more regular through the western third of the region than thought previously and there has also been a recent trend towards winter occurrences.

The primary moult of Curlew Sandpiper Calidris ferruginea was studied at a staging area in the south of Europe. The duration of primary moult was estimated as 73 days (9 August to 21 October), a shorter period than those reported in the wintering areas. Birds in moult showed a lower speed of fat accumulation than non moulters. An increase in the proportion of moulting birds was detected at the end of the migratory period, probably as a result of a longer staging time of moulting birds in the study area. The number and sex‐ratio of birds in wing moult showed a great annual variation. The brooding system of this species, in which only females give parental care, and the great annual variation in breeding success could be two of the factors that explain the great yearly variation in the moult schedule of Curlew Sandpiper.

Biometric data were collected for Sanderlings breeding at northern Taimyr in 1982–92. They allowed the calculation of discriminant functions, using wing, bill and (or) total head lengths, for sexing Sanderlings, belonging to Siberian population. Geographic comparisons revealed that birds from Taimyr have shorter bills than birds on South African wintering grounds, which leaves the problem of origin of long‐billed South‐African Sanderlings unsolved. Sanderlings had minimal body mass in pre‐nesting and brood‐rearing periods, and noticeably larger mass during incubation. Females were consistently heavier than males (regardless of size). The mean body mass fell in late seasons due to a probable decrease in food availability.

The existence of possible differences in homing performances between adult and juvenile Dunlins was investigated at the beginning of two wintering seasons, when 49 adults (1992) and 51 first-year birds (1993) were caught in the Lagoon of Venice and displaced to Cervia Salines. Both sites (133 km apart) are important winter resorts for the species at the Italian and Mediterranean level. In a previous season, a control series of 47 birds belonging to both age classes were caught and released at Cervia Salines. The patterns of return at the capture site by the displaced birds did not statistically differ between the two age groups and the estimated percentage of homed birds after 50 days in the Lagoon of Venice was similar to the resighting rate of control birds in Cervia. Juvenile Dunlins seem to have developed a wintering site attachment by early December, i.e. 1-2 months after their arrival on the wintering grounds.

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.

Summary Summers, R. W. 1994. The migration patterns of the Purple Sandpiper Calidris maritima. Ostrich 65: 167–173. The Purple Sandpiper breeds largely in the Arctic, and winters (boreal season) on the rocky shores of the north Atlantic, further north than any other sandpiper. As the populations from Canada, Greenland, Iceland, Svalbard, Norway and Russia differ in wing and bill lengths it is possible to match measurements taken from breeding birds with samples of birds caught in winter. Ringing recoveries, especially from colour marked birds, have also helped to determine migration routes and wintering areas. Four populations move to the nearest ice-free coast. Two populations move south of the nearest ice-free coast, being replaced by larger birds from a more northerly population (“chain migration”). Only the north Canadian population is believed to migrate a long distance, “leap-frogging” other winter populations. These patterns are discussed in relation to theories for the migration patterns of waders.

Capsule Of three hypotheses examined, the most likely seems to be avoidance of salt stress.

Field experiments suggest that Dunlins rely on visual prey detection by day and tactile prey detection by night to a larger extent than observations of their foraging technique would initially indicate.

Summary 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 nere...

Comparisons are made between counts of shorebirds at high water roosts and low water feeding grounds on the Wash, east England. During autumn and winter 1985–87, Shelduck, Tadorna tadorna, Oystercatcher, Haematopus ostralegus, Ringed Plover, Charadrius hiaticula, Grey Plover, Pluvialis squatarola, Knot, Calidris canutus, Dunlin, Calidris alpina, Bar-tailed Godwit, Limosa lapponica, Curlew, Numenius arquata Redshank, Tringa totanus and Turnstone, Arenaria interpres were counted at roost as part of the Birds of Estuaries Enquiry. These were compared with counts made by us at low water on the adjacent inshore mud- and sandflats. Of 45 comparisons made, 13 differed by less than 25%, 20 by 26–50% and 12 by more than 50%. The high water count exceeded the low water count in 25 comparisons. Counts of Shelduck, Oystercatcher and Knot were the most consistent. Most discrepancies appeared to be due to either an inability to count all areas at low water or by birds, and sometimes roosts, being missed. The correspond...

The biometrics of breeding Purple Sandpipers from southern and northern Norway and Svalbard were described from fresh material There was a slight size difference for the birds in the two areas of Norway, and the Svalbard birds were significantly larger than the Norwegian birds. Previously collected data sets were compared with the current measurements.

The results of a comparative study of a trophic spectre of three species of shorebirds (Tringaflavipes. Calidrisfuscicollis and Charadrius collaris), are given in this contribution. They show the mechanisms of isolation despite sharing the same source of food. Considering the diversity of food, the mechanisms of isolation can be shown in the trophic as well as in special dimension of the ecological niche. Specialization on certain types of food and different types of habitat use are the prevalent strategies to avoid competitive exclusion.

Droppings of Dunlin Calidris alpina and Grey Plover Pluvialis squatarola were collected on the Wash, south-east England, and examined for remains of prey species taken. Dropping analysis was found to be useful in describing the diet of these two waders. In addition to confirming known prey species, previously unrecorded prey were discovered: in the case of Dunlin, worms -of the families Spionidae and Phyllodocidae and in the case of Grey Plover, the amphipod crustacean Corophium volutator. Both Dunlin and Grey Plover were found to be taking the opisthobranch mollusc Retusa obtusa¸, a prey species which has not been recorded in the diet of waders before.

Summary Summers, R. W., Cooper, J. & Pringle, J. S. 1970. Distribution and numbers of coastal waders (Charadrii) in the southwestern Cape, South Africa, summer 1975–76. Ostrich 48: 85–97. A survey of the distribution and numbers of waders (suborder Charadrii) in the coastal regions of the southwestern Cape was conducted from November 1975 to February 1976. Forty-four coastal wetlands and 49 sections of coastline were visited between the Olifants and Groot-Brak rivers. The estimated total wader population was 119 008 of which 102 841 (86,4%) were Palaearctic migrants. Langebaan Lagoon and the Berg estuary supported the largest numbers. The Curlew Sandpiper Calidris ferruginea and Sanderling Calidris alba were the most numerous species. The abundance of waders was greater on west coast shores than along the south coast.

Summary Puttick, G. M. 1978. The diet of the Curlew Sandpiper at Langebaan Lagoon, South Africa. Ostrich 49:158-167. Nereid worms (mainly Ceratonereis erythraensis) and the hydrobiid gastropod Assiminea globulus were the most important prey items throughout the year for Curlew Sandpipers Calidris ferruginea feeding at Langebaan Lagoon. Other important items were the amphipod Urothoe grimaldi, the crabs Hymenosoma orbiculare and Cleistostoma edwardsii and dipteran larvae (Stratiomyidae). Immature Curlew Sandpipers took smaller prey items than adult birds. The diet of male and female birds differed in the proportion, sue and range of prey items taken.

Summary Summers, R. W., Underhill, L. G, Waltner, M. & Whitelaw, D. A. 1987. Population, biometrics and movements of the Sanderling Calidris alba in southern Africa. Ostrich 58:24-39. The Sanderling in southern Africa is restricted to coastal habitats. The population during the austral summer was estimated to be 78000. Highest densities occurred along the west coast where the Benguela Up-welling System gives rise to enriched inter-tidal invertebrate communities, partly through the stranding of large kelps. Immigration from the breeding areas took place during September and November. Numbers were highest during mid summer and emigration took place in April. The summer population at Lange-baan Lagoon was biased towards males (72%). The percentage of first-year birds in the summer population fluctuated on a three-year cycle, coinciding with the lemming cycle in the Taimyr Peninsula in Siberia. It is suggested that the cyclic fluctuation is caused by Arctic Foxes, and perhaps other predators, feeding on lemmi...

Summary Summers, R. W. & Waltner, M. 1978. Seasonal variations in the mass of waders in southern Africa, with special reference to migration. Ostrich 50:21-37. Seasonal variations in the mass of various wader species are described from data collected mainly in the southwestern Cape from 1970 to 1977. 1Y+ (older than one year) Turnstones Arenaria interpres, Ringed Plovers Charadrius hialicula, Great Sandplovers C. leschenaultii, Grey Plovers Pluvialis squatarola, Knots Calidris canutus Sanderlings C. alba, Terek Sandpipers Xenus cinereus. Common Sandpipers Tringa hypoleucos, March Sandpipers T. stagnatilis, Greenshanks T. nebularia, Bartailed Godwits Limosa lapponica and Whimbrels Numenius phaeopus showed an increase in mass between late March and early May. This was associated with the accumulation of fat deposits as measured in Turnstones and Sanderlings. 1Y-t-Turnstones, Knots and Sanderlings had their smallest mass in mid summer (December and January). Ruffs Philomachus pugnax had a slight rise in mass...

Dublin weights remain more or less constant, at a relatively low level, during the period of wing moult. Possibly reduced flight-efficiency at this time requires such a strategy.

Summary Pringle, J. S. & Cooper, J. 1975. The Palaearctic wader population of Langebaan Lagoon. Ostrich 46:213-218. Monthly counts of Palaearctic waders were made at high tide in three areas of Langebaan Lagoon, southwestern Cape, during 1973 and 1974. A total of sixteen species was observed. The five commonest species, in order of abundance, were Curlew Sandpiper Calidris ferruginea, Grey Plover Squalarola squatarola, Turnstone Arenaria interpres, Knot C. canutus and Sanderling C. alba. Together they formed 95,7% of the population counted. Waders arrived in September and departed in March and April. Overwintering populations of the commoner species were observed. Estimates of the total population size of the lagoon were 41 000–55 000 in summer and 10 500 in winter. These figures are of value for nature conservation and show that the lagoon is a wetland of international importance.

This paper presents a method for determining the sex of adult Sanderling from measurements of bill and wing length taken in the field, using a discriminant function based on birds of known sex. Discriminantly sexed samples of birds caught at Teesmouth indicated a predominance of females in the population throughout the year. The seasonal pattern of weight changes was similar in the 2 sexes, though female birds were consistently heavier than males.

Summary Pringle, J. S. & Cooper, J. 1977. Wader populations (Charadrii) of the marine littoral of the Cape Peninsula, South Africa. Ostrich 48: 98–105. Waders (Charadrii) were counted regularly on two stretches of coastline, totalling 5,6 km, on the Cape Peninsula from January 1975 to July 1976. Eight Palaearctic species and seven indigenous species were observed. Arrival of migrants extended from mid-August to January. Autumn departure of Curlew Sandpipers Calidris ferruginea occurred approximately six weeks before departure of Sanderlings C. albu. No overwintering populations of migrant waders were observed. Information is presented which suggests that overwintering Turnstones Arenaria interpres, but not Sanderlings, Maycongregate at a sheltered coastal wetland. Observations of marked birds suggest that individual Sanderlings regularly use particular feeding localities. Populations of indigenous waders showed little seasonal variation in numbers, Flocking was observed in winter.