Dunlin papers:

references, abstracts and comments. Where there is no abstract, an abstract has been written, where abstracts are too long they have been abridged. Abstracts in languages other than English have been translated into English. Some 200 papers will be entered to start with. The comment is personal, it points out errors and possible follow-ups, it is begun: CP:
(There is an overall problem from the early or mid-nineties: editors are unable to evaluate the worth or substance of empirics, therefore a couple of serious errors are in circulation right now; nobody notices them and nobody cares. Publishing as an invitation to public discussion doesn't function any longer, and I think this is part of a paradigm crisis to come - or already in progress. The only instance I could think of to address the problem is Wader Study Group - but it should not be done in writing - I think some sort of panel discussions over topics like "Do waders migrate and moult at the same time?", "Do juvenile Dunlin migrate unaccompanied by adults?" and "Is the progress of young Dunlin "trial and error"?" are necessary. This in order to keep the people involved from evading and ducking: both the authors responsible and the difficult questions must be confronted).

A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, Å

Boere, G. C. (1976): The significance of the Dutch Waddenzee in the annual life cycle of Arctic, Subarctic and Boreal waders. Part 1. The function as a moulting area. Ardea 64: 210 - 291.

CP: Boere doesn't distinguish suspended moult from arrested moult, and gives the regression MOULT SCORE on TIME (approximating the average moult score of an individual in the population at any given time; cf Ginn (1975), J. Orn. 116: 263-280), so the numerical results stated are misleading. (Such values are quoted by Ginn & Melville (1983) in "Moult in Birds" without comment, and by Meltofte (1993) in the following way: remige moult lasts c3 months and is finished during September and October (Boere l.c.))). Still, the transparency of the paper makes it valuable; the reader can make the correct conclusions for himself. The possibility of widespread moult start on breeding grounds is dawning on Boere by this time, as it is on Gromadzka ten years later. (So what is quoted here is an incorrect conclusion when it comes to the duration of moult, and several of the internal quotes may be incorrect as well).

Nieboer (1972) and Boere et al (1973, in prep.) have shown that the birds which moult their remiges in the Dutch Waddenzee mainly belong to the subspecies Calidris alpina alpina. The mean time needed in an individual bird to complete the moult of remiges is about 87 - 94 days. This differs from the time calculated for birds belonging to other populations, e.g. C. a. schinzii moulting in Morocco and Mauritania, 60 - 70 days (Pienkowski 1972, Dick 1975, Pienkowski et al. 1976); C. a. sakhalina breeding and moulting at Point Burrow, Alaska, 65 - 70 days; C. a. pacifica moulting in the Yukon-Kuskokwim Delta in Alaska, about 97 days (Holmes 1966 a, 1966 b, 1971, Maclean & Holmes 1971).

(The following part of the discussion deserves to be quoted as well). Lilja (1969) found 20 % of the birds in Finland in arrested moult; Lessels (1974) examined 17 adult Dunlins in Northern Norway, 2 of which being in arrested and 9 in active wing moult. This shows that at least part of the birds belonging to the subspecies C. a. alpina (including C. a. centralis, if accepted), starts primary moult on or near their northern breeding grounds, or during the first part of their migration to the Waddenzee or elsewhere in Western Europe. Still I found arrested moult in only few specimens, and it is virtually impossible to detect in any moulting wing whether it had started from an arrested or non-arrested stay.

Boere, G. C. & C. J. Smit (1981): Dunlin (Calidris alpina (L.)). pp. 157 - 169 in: Smit, C. J & W. J. Wolff, Birds of the Wadden Sea. Balkema, Rotterdam.

Brennan, L. A., Buchanan, J. B., Schick, C. T., Herman, S. G. & T. M. Johnson (1984): Sex determination of Dunlins in winter plumage. J. Field Ornithol. 55: 343 - 348.

Discriminant function analysis was used to create a statistical model that correctly predicted the sex of Dunlins in 91.5 % of a sample of 200 bierds. Bill length had the greatest discriminating power, followed by weight and wing length. Dunlins in this study were slightly smaller than those reported from other studies in western North America. We recommend researchers to test this model with similar data from other Dunlin populations and, if necessary, produce area specific sex determination models. Researchers wishing to assign sexes to Dunlins banded for behavioral studies should do so only if the posteríor probability of correct classification exceeds a predetermined probability cutpoint. When discriminant analysis is used to infer the sex ratio of a Dunlin population, the entire sample should be used.

Brenning, U. (1987): Der herbstliche Durchzug des Alpenstrandläufers im NSG Langenwerder. Ber. Vogelw. Hiddensee 8: 4 - 19.

The passage of adult and juvenile birds takes place in several waves being almost completed in the end of October. During the years from 1976 to 1985 approx. 17 000 Dunlins were caught. The average ratio between adult and juvenile birds was 1 : 5, the measure of dispersion being from 1 : 1.3 to 1 : 10. Adult birds stayed in average for 2.9 days and birds from the current year for 11.4 days. The average weight of adult Dunlins was 45.3 (34-67) g and that of juvenile ones 46.1 (27-72) g. Juvenile birds showed a max. daily increase in weight of 6.9 % of their body weight, in average of 1.5 - 0.7 % after a negative tendency during the first days. The problem of the appearance of the subspecies C. a. sakhalina could not yet be clarified definitely.

Brenning, U. (1989): Der Zug des Alpenstrandläufers (Calidris alpina) auf der Grundlage von Beringungen, Wiederfunden und Kontrollen in der DDR. Ber. Vogelw. Hiddensee 9: 16 - 38.

About 28.500 Dunlins were trapped and ringed in the GDR from 1964 to 1987, most of them at the coastal site on Langenwerder. This contribution analyses 763 reported recoveries (541 birds with Hiddensee rings and 222 ringed abroad) and draws conclusions concerning the destinations of the Dunlin populations migrating through the GDR. While only a small proportion of the juvenile birds migrating in July and August spends the winter in Europe, the Channel coast of France and the European Atlantic coast are the most important wintering regions for the majority of juveniles. Most adult Dunlins rest in the tidal marshes of the North Sea and the Wash (east British coast) during the autumn moult, but in winter many of them migrate to the west and south coasts of the British Isles. Some of them winter on the West European coast, and a few in the Mediterranean. Juveniles that reach Great Britain via Norway during their first migration later migrate across the Baltic Sea to their wintering grounds.

Buchanan, J. B., Schick, C. T., Brennan, L. A. et al. (1988): Merlin predation on wintering dunlins: hunting success and dunlin escape tactics. Wilson Bull. 100: 108-118.

Interactions between Merlins (Falco columbarius) and Dunlins (Calidris alpina) were studied at estuarine areas in western Washington during winter, 1979 to 1985. Twenty-five of 111 hunting flights by Merlins were successful (22.5 %). Five of seven capture attempt techniques were used successfully with a success rate of 4.9 %. The most common capture techniques were the stoop at a flock and the chase of an individual isolated from the flock. Most hunting flights (54 %) lasted less than 1 min, but hunts of over 5 min were observed (10 %). Hunting success varied little with the duration of the hunting flight or the size of the Dunlin flock initially targeted. Success rates for hunting flights by Merlins were much higher in Washington (22.5 %) than reported from California (12.5 %); these higher rates may be the result of a functional response by Merlins in Washington. Dunlins exhibited three distinct types of synchronized predator evasion flights. Dunlin isolated from flocks were often pursued and captured. The most common evasive measure used by isolated birds was a lateral dodge executed while in linear flight away from the flock.

Chao, A., S.-H. Chang & Y. H. Tsung (1991): Sexing Dunlins of Kung-Du area by a statistical method. Journal of Chinese Association, 29: 131-143.

Clutton-Brock, T. H. (1986): Sex ratio variations in birds. Ibis 128: 317 - 329.

Significant variation in the sex ratio at hatching is unusual in birds. In contrast, sex differences in juvenile mortality have been found in a variety of species, especially when food is scarce. In some cases, these differences may be a consequence of reduced viability of males when food is scarce but, in others, the available evidence suggests that parental manipulation is involved.

Cramp, S. & K. E. L. Simmons (eds.) (1983): The Birds of the Western Palearctic. Vol 3. Oxford: Oxford University Press.

Cresswell, W. & D. P. Whitfield (1994): The effects of raptor predation on wintering wader populations at the Tyninghame estuary, southeast Scotland. Ibis 136: 223 - 232.

Raptor predation on waders was studied by direct observation of raptors hunting a known wader population and subsequent recovery of dead waders. In each of three winters, raptor predation was shown to be the most significant cause of mortality in most small wader species. Sparrowhawks Accipiter nisus, Merlins Falco columbarius and Peregrines F. peregrinus attacked waders with a success rate of 11.6 %, 8.8 % and 6.8 %, respectively. Most waders attacked or found dead were Redshanks Tringa totanus and Dunlin Calidris alpina; most were killed by Sparrowhawks. Kleptoparasitism of raptors carrying prey by Carrion Crows Corvus corone significantly increased the winter mortality of some waders. Redshank populations were most affected by raptor predation; over 50 % of the total population (which was found to be closed during most of the winter) and over 90 % of the juvenile population were taken in two winters: juveniles were more likely to be killed by raptors.

Cresswell, W. (1996): Surprise as a winter hunting strategy in Sparrowhawks Accipiter nisus, Peregrines Falco peregrinus and Merlins F. columbarius. Ibis 138: 684 - 692.

Davidson, N. C. (1983): Formulae for estimating the lean weight and fat reserves of live shorebirds. Ringing & Migration 4: 159-166.

Formulae for calculating the lean weight and fat reserves of shorebirds from their total body weight and wing-length and / or bill-length are given for six species wintering in Britain. General formulae for shorebirds in various seasons and areas are also given. The application of these, and other published formulae, for estimating lean weight is discussed. Formulae derived from single species should be used whenever possible. A better estimate of lean weight is obtained from formulae using both wing-length and bill-length than from formulae using only one of these. The general formulae can be used when a single-species formula is not available.

CP:In Dunlin the formulae using bot wing- and bill-length are slightly better than formulae using only bill-length. 40 ad, NE England in winter: LW = (0,005WL + 0,015BL + 2,58)3, 32 juv, same conditions: LW = (0,011WL + 0,012BL + 2,02)3.

Davidson, N. C. (1984): How valid are flight range estimates for waders? Ringing & Migration 5: 49-64.

Assessments of fat loads and flight ranges are important in studies of migration phenology. Departure condition, which is an essential input for flight range calculations, is difficult to measure accurately, especially for live birds. Problems arise from the estimation of fat load and the rate of fat storage, water loss, and departure time. Flight range models give range estimates for waders differing by up to 2.5 times for the same fat load. The validities of the models are tested against known migrations of waders. Ranges in still air from flight metabolism models (McNeil & Cadieux 1972, Greenewalt 1975, Summers & Waltner 1979, this study) predict observed range most accurately. However, range modifiers, particularly wind speed and direction, altitude, flight speed, and aerodynamic drag, will all increase predicted range, when applied to waders. With information on actual conditions of migration, Pennycuick's (1975) aerodynamic model may be the best range predictor. Since range modifiers are difficult to apply, flight range can be approximated by calculation of a still-air range from the flight metabolism model derived in this paper. Before they are used for other groups of birds, models should be tested against known migration of these groups.

CP: In an Appendix four different formulas for calculating distances are presented, in addition there is a BASIC-program for the same formulas.

Davidson, N. C. (1984): Changes in the conditions of dunlins and knots during short-term captivity. Can. J. Zool. 62: 1724 - 1731.

Davidson, N. C., Uttley, J. C. & P. R. Evans (1986): Geographic variation in the lean mass of dunlins wintering in Britain. Ardea 74: 191 - 198.

Dekker, D. (1998): Over-ocean flocking by dunlins, Calidris alpina, and the effect of raptor predation at Boundary Bay, British Columbia. Can. Field-Nat. 112: 694-697.

Dierschke, V. (1994): Timing of occurrence and fluctuations in abundance of Calidris sandpipers staging on the island of Helgoland, SE North Sea. Vogelwelt 115: 59 - 68. The seasonal patterns of occurrence and year-to-year variation in abundance of staging Calidris sandpipers on Helgoland were analysed. One to two hundred Purple Sandpipers C. maritima winter annually. Of all other species few birds rest during spring and adult autumn migration, but high numbers occur during juvenile autumn migration. The numbers of juveniles show annual fluctuations, expressed as a juvenile index (sum of maximum counts of all five-day-periods during juvenile migration per year). Coincidence of fluctuations in juvenile index of Calidris species and percentage of juveniles in Dark-bellied Brent Geese Branta b. bernicla wintering in Central Europe suggest that the juvenile index indicates the breeding success in the Arctic. There is a high coincidence of breeding success between the Taimyr-breeding species Knot Calidris canutus, Sanderling C. alba, Curlew Sandpiper C. ferruginea and Brent Goose, all of which produce low number of juveniles approximately every third year. This is less pronounced in Dunlin C. alpina and Little Stint C. minuta, probably because of the larger breeding area from which these birds originate. In demonstrating a very poor breeding success in the four Taimyr breeding species every three years, the Helgoland data support the hypothesis of Roselaar (1979) and Summers (1986) about the correlation between breeding success of arctic waders and geese and cyclic changes in lemming abundance. In years following peak lemming abundance high predation pressure causes catastrophic losses of eggs and young in Taimyr breeding waders and geese. Counts on Helgoland can be used to monitor breeding success of Arctic breeding waders, because here surveys can be conducted more efficiently than in the Wadden Sea and reflect a representative sample of the migration in these species.

Dierschke, V. (1996): Unterschiedliches Zugverhalten alter und junger Alpenstrandläufer Calidris alpina: Ökologische Untersuchungen an Rastplätzen der Ostsee, des Wattenmeers und auf Helgoland. Dissertation, Göttingen. (Differential migration in adult and juvenile Dunlins: ecological studies at staging sites of the Baltic Sea, the Wadden Sea and Helgoland.

Here follows the first block of the Summary; blocks 2 - 3 concern food, 4 foraging rhythms, 5 fat deposition rates, 6 intraspecific competition, 7 predation, 8 site tenacity).

In July and Auugust, most adult Dunlins migrate fast and directly from their breeding area in northern Eurasia to staging areas in the Wadden Sea and the Wash, where they conduct or complete their post-nuptial moult. Juveniles follow later, more slowly and independently from adults. Instead of concentrating in moulting areas they disperse over European coasts and are first found mainly at the Baltic Sea and along the Norwegian coast. Juveniles ringed at the latter two areas behave different in selecting moulting areas as adults in later years. Juveniles migrating northerly are found mainly in the Wash, those migrating southerly mainly in the Wadden Sea. It is proposed that experiences during the first year of life are responsible for the selection of a moulting area. To test this hypothesis I investigated different ecological aspects of wader habitats in the Wadden Sea, at the southern coast of the Baltic (Hiddensee, Langenwerder) and at the island of Helgoland (German Bight, SE North Sea), which could explain why Dunlins do not come back to their juvenile stopover sites at the Baltic and at Helgoland.

CP: I disagree with Dierschke on many points concerning migration, and I think that his idea of "independent migration of juveniles" must have been launched against his own better knowledge, there must be data from Langenwerder showing him otherwise. The whole situation reminds me of the hidden anomalies of the Ptolemaian cosmology: in the present case every serious worker from the Baltic area knows that adults do accompany juvenile migrating Dunlin throughout the autumn, but they "are not there" because juveniles migrate on their own in the cosmology of Dierschke.

Dierschke, V. (1998): High profit at high risk for juvenile Dunlins Calidris alpina stopping over at Helgoland (German Bight). Ardea 86: 59-69.

During autumn migration, up to 1100 juvenile Dunlins Calidris alpina per day forage on the island of Helgoland (SE North Sea). Beds of washed up wracks and kelp are used as a feeding habitat where they take kelp fly larvae (Coelopidae) at a high rate (17.8 larvae min-1). This high energy intake allows rapid fattening (1.7-3.3 g day-1) and short lengths of stay (about 4-5 days), leading to a high daily turnover of individuals (0.2-0.7 day-1). Despite the good conditions for meeting energetic requirements, staging at the island incurred a high predation risk from migrating birds of prey. Different feeding priorities might be one reason why most adult Dunlins avoid Helgoland as a staging site and instead aggregate at large staging areas such as the Wadden Sea, where individual depredation risk is more than 50 times less.

Dierschke, V. & A. J. Helbig (1999): Baltic Sea windflats as spring staging site for Dunlins Calidris alpina. Wader Study Group Bull. 90: 42-46.

From March and April onwards, about 3,000 - 6,000 Dunlins Calidris alpina stage before spring migration in three windflats at the island of Hiddensee (German Baltic coast). In the evening hours between 27 May and 3 June, most birds depart in flocks of 10-500 birds in a north-north-easterly direction. The late departure indicates that these birds belong to Siberian breeding populations. Due to the lack of ringing recoveries it is not known whether the spring staging Dunlins from the Baltic belong to populations wintering along the European Atlantic coast or in the western Mediterranean Sea.

Dierschke, V., Kube, J., Probst, S & U. Brenning (1999): Feeding ecology of dunlins Calidris alpina staging in the southern Balic Sea, 1. Habitat use and food selection. J. Sea Res. 42: 49 - 64.

Dierschke, V., Kube, J. & H. Rippe (1999): Feeding ecology of dunlins Calidris alpina staging in the southern Balic Sea, 2. Spatial and temporal variations in harvestable fraction of their favourite prey Hediste diversicolor. J. Sea Res. 42: 65 - 82.

Spatial and temporal variations were studied in the distribution of the fraction of the polycaete Hediste diversicolor harvestable for dunlins under non-tidal conditions in Baltic Sea windflats. The investigations were carried out in 1991 and 1995 near the island of Hiddensee, in the Bock and Bessin windflats, the most significant staging areas for shorebirds on the southern Baltic Sea coast. Density and biomass distribution patterns of H. d. were found to be determined by exposure time, but not by sediment parameters. Whereas the density distribution and the size-frequency distribution patterns of H. d. showed large spatial and seasonal variation in the Bock windflat, both parameters showed little spatial but obvious seasonalvariability in the Bessin windflat. Active migration and passive bedload transport are considered to be the most important causes of the observed differences. When the sediment was inundated or still wet after an emersion, H. d. lived in the top 3 cm of the sediment. The low level of surface activity observed, and the low organic matter values of the sediment suggest that filter feeding was the most common feeding mode of H. d. in the study area. H. d. retreated to deeper layers when the sediment became dry. No correlations were found between numbers of dunlins and density or biomass of H. d.. Dunlins selected their foraging habitat according to substrate conditions and preferred shallow water and recently emerged sandflats. As a consequence, dunlins foraging in windflats were usually concentrated in dense flocks in the shallow water surrounding these exposed sandflats. Feeding conditions varied between sites and depended mainly on the topography of the windflat and its water-current regime. High densities of feeding dunlins can locally cause heavy exploitation of the standing stoch of H. d. during prolonged periods of constantly low water. However, the availability of several windflats in the study area around the island of Hiddensee at slightly different levels compared to mean sea level allows the shorebirds to switch between sites, and therefore to make use of a spatially and temporally enlarged supply of harvestable prey.

DOF. Fugle på Sjaelland. (1986 - 1993): (Annual Report from Sealand)

Dugan, P. J. (1981): The importance of nocturnal foraging in shorebirds: A consequence of increased invertebrate prey activity. In N. V. Jones and W. J. Wolff (eds.): Feeding and survival strategies of estuarine organisms, pp. 251-260. Plenum Press, New York.

Edelstam, C. (1972): The visible migration of birds at Ottenby. Vår Fågelvärld, suppl. 7.

CP: Quoted here is one conclusion" from "The seasonal rhythm", p. 50 and a few lines from the "Notes" section, p. 348:

The time differential in departure for the southward migration between young and adult waders also varies strongly according to the species. Measured from the last adult peak, the peak for the immature grey plover Pluvialis squatarola is delayed five or six weeks, and the same differential applies to the bar-tailed godwit Limosa lapponica and the northern Russian dunlin Calidris alpina,...

1. The passage of adult dunlins of northern origin, beginning about 10 July, reaches a peak in the last week of that month and usually ends about 20 August, although minor waves have been noted in September and, very occasionally, in October. 2. Such adult birds as are found in the company of the late juveniles obviously are of the same origin; whether they do occur also in summer remains to be clarified.

Engelmoor, M., Roselaar, C. S., Boere, K. & E. Nieboer (1983): Post-mortem changes in measurements of some waders. Ring. & Migr. 4: 245 - 248.

Engelmoor, M. & C. S. Roselaar (1998): Geographical Variation in Waders. Kluwer Ac. Publ. With a diskette containing data and an auxiliary program.

CP: A peculiar book; if BTO:s "Guide to the identification and ageing of Holarctic Waders" lies at one pole, this book lies at the opposite; there is no didactic ambition whatsoever, and before reading it you have to brush up your statistical knowledge (if there is any) for several hours. In addition the fact that all measurements were taken on dry museum specimens reduces the value of the book to "practicists", field workers. It goes without saying that this approach is good enough within its own context - in the museum world - but how about the needs of the catching stations, the field projects? With this reservation a few lines from the discussion of the Dunlin are quoted here:

The populations breeding between N Fennoscandia and the Kolyma Delta are evidently polymorphic. The N Fennoscandia - Yamal population differed from both the Taymyr- and the Anabar-Kolymsk population, whilst both latter were nearly always indistinguishable in the morphometric analyses. We conclude on the recognition of 2 taxa in this region: the western 'alpina' type is characterized by (1) smaller dimensions, (2) lack of 'adult buff' wing coverts, (3) narrow white edges along the outer vanes of the primaries and (4) the absence of primary moult on the breeding grounds; the eastern 'centralis' type is larger, has 'adult buff' coverts, more white on the vanes and starts primary moult during breeding. This difference is supported by mtDNA research (Wenink et al. 1996) These are good reasons to distinguish both as separate subspecies.

Evans, P. R. (1964): Wader measurements and wader migration. Bird Study 11: 23 - 38.

Evans, P. R. (1986): Correct measurement of the wing-length of waders. Wader Study Group Bull. 48: 11.

CP: The suggested steps are: 1. Press wing firmly against end-stop of wing-rule. 2. Straighten curve of wing. 3. Stroke along feathers to their end.

Evans, P. R., Goss-Custard, J. D. & Hale, W. G. (eds.) (1984): Coastal waders and wildfowl in winter. Cambridge: Cambridge University Press.

Ferns, P. N (1978): The onset of prebasic body moult during the breeding season in some high-Arctic waders. Bull. Br. Orn. Club 98: 118 - 122. No summary; field-work in NE Greenland, "prebasic" = postnuptial.

"None of the 11 C. alpina captured showed any trace of prebasic moult, but they were all captured close to the date when their eggs hatched. This species undergoes the whole of the prebasic moult on the breeding grounds in some regions (Holmes 1971), so it is particularly surprising that none was recorded in Greenland.

Ferns, P. N. & G. H. Green (1979): Observations on the breeding plumage and prenuptial moult of Dunlins, Calidris alpina, captured in Britain. Gerfaut 69: 286 - 303.

Subspecific and sexual differences in the breeding plumage of three races of Dunlins, Calidris a. alpina, C. a. schinzii and C. a. arctica are described. These races are illustrated by means of birds captured during their spring migration through the Severn Estuary. Many C. a. alpina undergo the whole of their prenuptial moult in the latter area, whereas the other two races arrive in almost complete breeding plumage. Following the prenuptial moult, the feathers abrade rapidly, producing a sequence of quite well defined stages, in each of which the bird has a different external appearance.

Folkestad, A. O. (1975): Wetland bird migration in Central Norway. Ornis Fennica 52: 49 - 56.

Fuchs, E. (1973): Durchzug und Überwinterung des Alpenstrandläufers Calidris alpina in der Camargue. Orn. Beob. 70: 113-134. (Transmigration and wintering of Dunlin in the Camargue) The Summary contains six blocks, viz.:

1. The present paper is based on 1,944 Dunlin caught and ringed in the Camargue from 1966 - 1972. Additional information is taken from field observations and from recoveries of 63 birds found in the Camargue that had been ringed elsewhere.
2. The Dunlin is a winter visitor and passage migrant in the Camargue. Total counts of the population are shown in fig. 1. Most of the juveniles arrive about 40 days later than the adults.
3. Most of the Dunlin in the Camargue belong to the nominate race C. a. alpina and there are also some C. a. schinzii. The mean bill and wing lengths are most similar to those of a population in the Timan-Tundra, and it is suggested that many birds come from that region. Juvenile Dunlins unlike adults show significant monthly increases in wing and bill lengths from August to October. Since these changes cannot be attributed to growth it is concluded that there are different populations migrating through the Camargue in succession.
4. Migrating Dunlins follow the North coast of Russia and then pass overland to the Baltic Sea (Nörrevang 1955). There their route divides and while most then follow the North coast of Europe the rest cross the continent to the Mediterranean Sea. It is thought that birds coming to the Camargue do not migrate any further but remain in the Mediterranean Basin. Recoveries so far show that they spread not only westwards but also eastwards from the Camargue, along the Mediterranean coast. Most of the recoveries indicate a high fidelity to the wintering area but some also show that birds wintering on the Atlantic coast or North Sea coasts may change to the Mediterranean and vice versa.
5. The moult of the body feathers of juvenile birds reaches a peak some 50 days later than that of the adults. The spring moult reaches a peak during late April and early May when migration is advanced and rapid. Many adult birds also moult their wing and tail feathers in the Camargue and some of them are in suspended wing moult when they arrive. These have therefore split the wing moult into two stages; one taking place on the breeding area, the other, on the wintering area. The moult schedule of wing and tail feathers is described in detail.
6. As usual in typical migrants the Dunlin has fat reserves during the migration period and also to a lesser extent in winter. Fat deposits are greatest during May, when birds are moving north again and in some cases may be almost 50 % of the total body weight. Deposits during autumn are much less than this and repeated captures have also shown that little fat is deposited by birds whilst in the Camargue at this time. This suggests a feeble migration-disposition. Calculations have shown however, that even in winter these deposits would still be sufficient to allow birds to cross the Mediterranean Sea in a non-stop flight.

CP: Fuchs has a deeper understanding of moult than most after-1990 authors, it is worth while reading him with attention to detail, but as far as I can see he has compared live measurements with uncorrected skin measurements.

Ginn, H. B (1975): The timing and sequence of the complete moult in the Dunnock (Prunella modularis) in Britain over an eleven year period. J. Orn. 116: 263 - 280.

Ginn, H. B. & D. S. Melville (1983): Moult in Birds. BTO Guide 19. BTO, Tring.

Glutz v. Blotzheim, U. N., Bauer, K. M. & Bezzel, E. (1975): Handbuch der Vögel Mitteleuropas. Band 6. Charadriiformes (Part 1). Wiesbaden: Akademische Verlagsgesellschaft.

Goede, A. A. & E. Nieboer (1983): Weight variation of Dunlins Calidris alpina during post-nuptial moult, after application of weight data transformations. Bird Study 30: 157 - 163.

Dunlin 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.

Goede, A. A., E. Nieboer & P. M. Zegers (1990): Body mass increase, migration pattern and breeding grounds of Dunlins, Calidris alpina, staging in Dutch Waddensea in spring. Ardea 78: 135 - 144.

Though a lot is known about the Dunlin, a highly variable wader species in many respects, there is still uncertainty whether substantial numbers of this species migrating through W. Europe in spring, breed as far as Siberia. Data on numbers, turnover, recoveries, body mass and bill length of the Dunlin, collected in spring in the eastern part of the Dutch Wadden Sea, are presented. Two kind of fattening strategies are clearly distinguished and seem to be used by two different groups of the subspecies alpina. The groups are temporarily segregated: one is present in April the other in May. It is argued that the latter one breeds in Siberia as far as the western part of the Taymyr peninsula.

CP: This paper relies too much on the representativity of Baltic catches where juveniles are involved, in my view all conclusions concerning autumn conditions are incorrect. It should be revised, or the topic should be treated anew.

Goss-Custard, J. D. (1969): The winter feeding ecology of the Redshank Tringa totanus. Ibis 111: 338 - 356.

Greenwood, J. G. (1979): Geographical Variation in the Dunlin Calidris alpina (L.). Ph. D. Thesis, Liverpool Polytechnic.

Greenwood, J. G. (1983): Post-nuptial primary moult in Dunlin Calidris alpina. Ibis 125: 223 - 228. No abstract, but the discussion opens with the following statement:

Two conclusions may be drawn from this study. First, there are differences between populations in the starting date of post-nuptial primary moult in Dunlin moulting on the breeding grounds. Secondly post-nuptial primary moult occurs on the breeding grounds only in populations to the east of the Ural mountains.

Greenwood, J. G. (1986): Geographical variation and taxonomy of the Dunlin Calidris alpina (L.). Bull. Brit. Orn. Cl. 106: 43 - 56. No summary.

Griffiths, J. (1968): Multi-modal frequency distributions in bird populations. Bird Study 15: 29-32.

CP:The method presupposes that bimodal distributions met with among birds are normal. Granted such normality it presents a graphic method for separationg the two merged constituent distributions. When there is a genetically sexed material the assumption of normality can be tested statistically; it may not hold in all cases.

Griffiths, J. (1970): The bill-lengths of Dunlins. Bird Study 17: 42-44.

CP: Analysis of bill-length materials presented by Cabot (1961, 1963, 1964), Evans (1964) and Soikkeli (1966), under the assumption that all materials are normal. This approach came to a halt thirty years ago, there is no reason why it should not be pursued again with better materials and - maybe - assumptions of non-normality.

Gromadzka, J. (1983): Results of bird ringing in Poland. Migration of Dunlin Calidris alpina. Acta Orn. 19: 113 - 136.

Gromadzka, J. & Przystupa, B. (1984): Problems with the ageing of Dunlins in autumn. Wader Study Group Bull. 41: 19-20.

Gromadzka, J. (1985): Further observations on the wing plumage of Dunlins. Wader Study Group Bull. 44: 32 - 33.

Some Dunlin which are more than 2 years old have inner median coverts with brownish-buff fringes. Thus some 2nd-year birds (more than 10 % in the Baltic region) may be aged incorrectly. The colour of new median coverts of Dunlins is not related directly to their age, but rather to when they start the autumn moult. Birds starting their moult earliest have brownish-buff colour in their medians. It is not known whether the initiation of moult by an individual depends on general moult strategy of the population it belongs to, or on its breeding status.

CP:These two short notes represent the "dawning" of knowledge about "adult buff" coverts and moult start on breeding grounds, so the authors are still groping their way. As a matter of fact there will be birds with grey coverts and birds with adult buff coverts sharing exactly the same moult status in the Sound area, S. Scania; here moulters with grey medians outnumber moulters with "adult buff" medians. I haven't seen any adult buff statistics from Langenwerder, and I would like to see better material from the mouth of Gdansk/mouth of Reva, including the ratio between grey and "abc" birds sharing the same moult status.

Gromadzka, J. (1986): Primary moult of adult Dunlins Calidris alpina of different age during autumn migration. Vår Fågelvärld. Supplement 11: 51 - 56.

CP:This paper has no abstract or summary, and there still are many unsolved problems. I quote from the text: The Dunlins discussed in this paper belong to the nominate subspecies C. a. alpina. They do not stop in the Vistula mouth region to complete moult. The birds which started to moult before their arrival at the Vistula mouth must have done so somewhere to the east of this area, in the breeding grounds or at the beginning of the autumn migration-route. They will continue the moult during their migration to the wintering grounds. AND: Some Dunlins staying at the Vistula mouth showed so-called arrested moult. Among moulting 2nd year Dunlins about 4 % of the individuals were in arrested moult, while in older birds this proportion varied from 7 % to 14 % (in different years). In the period from 23 August to 10 September 1984 more than 20 % of the adult Dunlin were in arrested moult (both age groups). Arrested moult was most often observed in birds being in an early stage of moult, after the replacement of 1 - 2 primaries.

Here two new insights are dawning: 1. that birds must have started moulting somewhere to the east of Vistula mouth, and 2. that some moulting birds do not grow remiges when migrating, they have "arrested".
CP: Here the term should be suspended moult. One would like to know: How close to completion/arrest are the rest of the birds, the "moulting" birds? Finally note: Gromadzka still believes that the birds continue to moult on migration, this is a sort of automatism in all authors by this time.

Gromadzka, J. (1989): Breeding and wintering areas of Dunlin migrating through southern Baltic. Orn. Scand. 20: 132 - 144.

Two main questions are discussed: (1) the eastern limit of Dunlin Calidris alpina populations migrating through the Baltic and (2) migration between the Baltic and the Mediterranean/Black Sea. Ringing and moult data show that some Dunlins migrating to the Baltic originate from more easterly regions than previously presumed. Many Dunlins migrating in autumn through the Baltic are in active moult. Some of them probably start their moult while breeding and originate from areas east of Urals. These birds show some easily recognized plumage patterns: their new median coverts (usually only some of them) are of "adult buff" type. This is a characteristic of Central and Eastern Siberia populations which start moulting very early, while still on their breeding grounds. Ringing data show that these birds winter in western Europe as well as in the Mediterranean. Some Dunlins from the Baltic migrate in autumn in a SE direction - to the Mediterranean and the Black Sea regions. The origin of these birds is not known. The SE direction may be used also by Polish breeding schinzii. Some Dunlins of the subspecies alpina, ringed in the Baltic in autumn, are controlled in spring at the Black Sea; in autumn they seem to migrate along a more northern route - through the Baltic, while in spring they choose a more southern route - through the Black Sea (loop migration).

Handel, C. M. & R. E. Gill (1992): Roosting behaviour of premigratory dunlins (Calidris alpina). Auk 109: 57-72.

We studied roosting behaviour of Dunlins (Calidris alpina) during late summer along the coast of the Yukon-Kuskokwim Delta, Alaska, in relation to tidal cycle, time of day, time of season, and occurrence of predators. Within Angyoyaravak Bay, peak populations of 70,000-100,000 Dunlins occur each year. The major diurnal roost sites were adjacent to intertidal feeding areas, provided an unobstructed view of predators, and were close to shallow waters used for bathing. At one site studied intensively, roosting flocks formed at high water consistently during the day but rarely at night. On about 75 % of the days, Dunlins also came to the roost at dawn and dusk when the tide was low. The size of the roosting flocks, the length of time birds spent at the roost site, and behavior at the roost site were highly variable throughout the season and significantly affected by both tide level and time of day. Roosting behaviour changed significantly between early and late August, as Dunlins underwent heavy wing and body moult, and began premigratory fattening. The reaction of Dunlins to potential predators, the formation of roosting flocks in response to light cues, and seasonal changes in social behaviour at the roost site suggested that communal roosting behavior may be related not only to the risk of predation but also to behavior during migration.

Hardy, A.R. & C.D.T. Minton (1980): Dunlin migration in Britain and Ireland. Bird Study 27: 81 - 92.

A combination of ringing recoveries and biometric data demonstrates that three separate Dunlin stocks migrate through these islands, where the winter population comprises birds from northern Europe.

Haukioja, E. (1971): Processing moult card data with reference to the chaffinch Fringilla coelebs. Orn. Fenn. 48: 25 - 32.

Van der Have, T.M. & V. van den Berk (1994): De mediterrane trekroute: een netwerk van wetlands voor watervogels. Limosa 67: 159 - 162.

The Foundation Working Group International Waterbird and Wetland Research (WIWO) stimulates and supports initiatives of volunteers to study tthe distribution and migration ecology of waterbirds for the benefit of nature conservation in theAfro-Palearctic migration system. Traditionally, projects focused on waterbirds migrating within the East-Atlantic Flyway, but in recent years attention has been extended to the Mediterranean region. These studies aimed to reveal more of the loop-migration of several wader species and to make acomparison between the major wetland types of both flyways. One of the characteristic wetland types of the Mediterranean Flyway is "windflat", that is, mudflat exposed by wind force. The largest system of windflats is found in the Sivash, a lagoon system in the Crimea near the Sea of Azov, Ukraine. In some brackish lagoons invertebrate densities equal those of tidal wetlands and these wetlands were found to be of international importance for arctic waders in general, and in particular for at least one third of the European population of Broad-billed Sandpipers Limicola falcinellus.(...)

Hedenström, A. & S. Sunada (1999): On the aerodynamics of moult gaps in birds. J. Exp. Biol. 202: 67 - 76.

Helbig, A.J., Dierschke, V. & R. Barth (1994): Ornithologischer Jahresbericht 1993 für Hiddensee und Umgebung mit Nachträgen zum Jahr 1992. Ber. Vogelwarte Hiddensee 11: 51 - 84.

Henriksen, K. (1985): Den postnuptiale faeldning af svingfjerene hos Hjejle Pluvialis apricaria. (Postnuptial moult of remex in Golden Plover). DOFT 79: 141-150.

Moult of the remiges was examined in 1268 wings from adult Golden Plovers Pluvialis apricaria collected in Denmark. Data on moult of a few museum skins collected in N. Scandinavia were added.
(...)Knowing the relative feather-mass of each primary (Tab. 1), the score of the primaries was converted to mass of new feather material.(...)
Moult of the primaries began with the shedding of the innermost primary (P1) and proceeded outwards towards the wingtip with a maximum of four feathers growing simultaneously. Only 0.8 % of the examined birds deviated from this descendant moult pattern. The inner primaries were shed in a more rapid succession than the outer ones, but the rate of progression during the beginning of the primary moult seemed to be slow in comparison with other waders moulting in temperate Europe.
One hundred and four wings showed evidence of suspended primary moult, and most (82 %) of these suspensions occurred with six or seven new primaries in the wing. Nearly all (92 %) of these suspensions were found in birds collected in the last half of August and the first half of September. In these two periods respectively 13 % and 14 % of the birds had suspended primary moult.
The secondaries were moulted in two groups. The moult of the first eleven, numbered from the wrist (S1-S11), most often started with the shedding of S1 or one of the two feathers S10 or S11. After the termination of the primary moult most birds had new S1 and S11, but the rest of these secondaries, and especially those in the centre of the row, were moulted to a lesser extent. On the average a little more than five of these eleven secondaries were moulted every year.
The sequence of moult in the tertials (S12-S15) was quite irregular and much individual variation concerning the onset of this moult was evident. Some birds initiated the tertial moult with the loss of the innermost primary, others not until the sixth primary was fully grown. Usually one or two tertials were growing at a time and suspensions were common, occurring in 207 of 526 birds with from one to three new tertials.
(...) The mean duration of primary moult in the individual bird was 101 days, and the total moulting period of these feathers covered 158 days.
...a complete separation of primary moult in the Golden Plover from breeding and migration would add to the enhanced difficulties of winter survival, compared to estuarine wintering waders in Europe, this species seems to experience. It is shown that about half of the Golden Plovers would have to complete the primary moult in December as a result of such a postponement. This late completion of moult, involving the long outer primaries, would coincide with a period of building-up of nutritional reserves and with cold-weather movements.

Holgersen, H. (1963): Tre tillegg til den norske fuglefauna. Sterna 5: 225 - 228.

Holmes, R.T. (1966): Molt cycle of the Red-backed Sandpiper (Calidris alpina) in western North America. Auk 83: 517 - 533.

In breeding populations of C. alpina in northern Alaska (71 ° N), the prebasic molt of adults is condensed int the short span of the arctic summer and overlaps with almost the whole of the breeding season. Molt begins early in the summer, and new flight feathers are completely grown before departure for winter quarters. At lower-latitude breeding localities in western Alaska (60-66° N), molt apparently starts later and breeding begins earlier than at higher latitudes, with the result that less overlap occurs. Even in the northern populations, however, the major portion of energy expenditure on molt comes in late summer when breeding is over and young Red-backs are fully grown.
Molt takes place during slow phases of both fall and autumn migrations, energy reserves evidently being sufficient to support both activities. In periods of rapid migration, molt is suspended.
The specialization in the molt schedule of C. alpina relate to the fact that this species, with its winter quarters in north-temperate regions, remains in the arctic through the end of summer, during which time it exploits tundra food sources in the absence of possible competitors.

Holmes, R.T. (1966): Feeding ecology of the Red-backed Sandpiper (Calidris alpina) in arctic Alaska. Ecology 47: 32 - 45.

Holmes, R.T. (1969): Differences in population density, territoriality, and food supply of dunlin on Arctic and subarctic tundra. - In: Watson, A. (ed.), Animal populations in relation to their food sources. Blackwell, pp. 303-317.

Holmes, R.T. (1971): Latitudinal differences in the breeding and molt schedules of Alaskan red-backed sandpipers (Calidris alpina). Condor 73: 93-99.

Holmgren, N., H. Ellegren & J. Pettersson (1993a): Stopover length, body mass and fuel deposition rate in autumn migrating adult dunlins Calidris alpina: evaluating the effects of moulting status and age. Ardea 81: 9 - 20.

CP: The theoretical "ambition" ruins this paper, it should be rewritten. Both Ibis and Ardea lack immunity to papers of this kind, the name Darwin acts as a kind of anaesthetic on editors.

Holmgren, N., H. Ellegren & J. Pettersson (1993b): The adaptation of moult pattern in migratory Dunlins Calidris alpina. Orn. Scand. 24: 21 - 27.

The post-nuptial primary moult of adult (2-year-birds included) Dunlins was investigated along the Baltic coast at Ottenby and Falsterbo, S. Sweden. These birds are on migration and only make short stopovers. During the years 1985-1988 at Ottenby, the proportions of moulting birds varied between 27 % and 61 %, probably due to annual variations in the timing of their passage. Compared with the older birds, 2-year-birds had more often initiated their moult and, on average, appeared in a more advanced stage of moult. Most of the Dunlins that had initiated moult were actively moulting - some feathers were not of full length and were found growing in a sample of caged individuals. The raggedness value (i.e. the gap due to not fully grown feathers) generally decreased in later stages of moult. By comparing raggedness values at given stages of moult, migrating Baltic birds generally had smaller gaps than non-migrating English conspecifics. Large gaps were correlated with lower body masses. The adaptive significance of commencing the moult prior to arrival on moulting grounds and of moult during migration are discussed.

CP: The material is faulty: incomplete, (both materials are faulty), and the authors look at captive birds, showing practically zero remige growth, without reacting. The whole paper is ruined by one very common presupposition: that Dunlin essentially migrate and moult at the same time. Holmgren brings this error on to Rösner 1997, and further still. He should be stopped and brought to some basic level of insight, and it should be done now.

Horvath, L. & A. Keve (1956): (transl.) The subspecies of Dunlin in Hungary. Ann. Hist. Nat. Mus. Hungary N.S. 7: 469 - 476.

Jehl, J. R. & B. G. Murray (1986): The evolution of normal and reverse sexual size dimorphism in shorebirds and other birds. In: Johnston, R. F. (ed.), Current Ornithology. Vol. 3. Plenum Press, New York and London, pp. 1 - 86.

CP: I really enjoyed the reading of this paper: its style, the learning of the authors, the enormous work behind. In most cases I avoid even the shadow of Darwin, but here the use of him seems in no way offensive, the thinking doesn't end there. Jehl and Murray distinguish ecological selection from sexual selection and quote Power 1980 with some sympathy:
Sexual selection is always at the root of sexual foraging differences, irrespective of the presence of other factors, because it is the only form of selection acting on the sexes per se, and thus the only form of selection producing incipient sexual foraging differences. It may seem that other forms of selection could produce sexual foraging differences by themselves because they favor the sexes being different. However, in the absence of preadaptations tending to make males consistently different in one way and females in another, differences of a particular kind would probably appear in one sex as often as the other and thus result in ecological polymorphisms not following sexual lines. Other forms of selection tending to produce sexual foraging differences are, thus, subordinate to sexual selection, effectively operating only after it has produced at least small differences between the sexes.
Furthermore, the general description of Calidridini is quoted here (p.15 - 16):
The calidridine sandpipers (genera Calidris [19 species], Limicola [1], Aphriza [1], Tryngites [1], Philomachus [1] and Eurynorhynchus [1] are the most interesting group of shorebirds because of their varied social systems, which are associated with size and plumage dimorphism. They are primarily probers.
Pitelka et al. (1974) classified the social systems in this subfamily. Group I includes 15 species (C. alpina, canutus, tenuirostris, subminuta, ruficollis, maritima, ptilocnemis, minutilla, bairdii, mauri, pusilla, himantopus, Limicola falcinellus, Aphriza virgata, Eurynorhynchus pygmeus), all of which are monogamous. The males establish territories and court females, mostly by using aerial displays. Both sexes incubate and care for the young (data are lacking for a few species), but in nearly all species the females tend to leave the brood before the chicks are fully grown. Color differences between the sexes are present in a few species (e.g. himantopus, canutus), with males being slightly brighter, but usually the differences are insufficient to allow consistent sexing in the field.
Group II includes the "serially polygamous species" (temminckii, minuta and some populations of alba). Courtship and territorial aggression are as in Group I, but females may lay two clutches, one incubated by the male and the second by the female. In some cases more than one male may be involved. There is no plumage dimorphism except in the Sanderling (C. alba), in which the males are noticeably brighter.
Group II includes "polygynous species" (fuscicollis, ferruginea, and possibly acuminata), in which the males maintain simultaneous pair bonds with more than one female. Males court females and establish and maintain territories with aerial and ground displays but take no part in caring for chicks. There are no sexual plumage differences in the Sharp-billed (C. acuminata) or White-rumped (C. fuscicollis) sandpipers, but males of the Curlew Sandpiper (C. ferruginea) are much more highly colored.
Group IV includes the "promiscuous species", the Pectoral (C. melanotos) and Buff-breasted (T. subruficollis) sandpipers, and the Ruff (P. pugnax). The males establish small territories to which females come for fertilization. Only the Pectoral has aerial displays, but these are slow courtship flights with shallow wing beats and occur close to the ground; intermale aggression takes place on the ground (Myers 1982). The females are solely responsible for incubation and care of the young. There is no plumage dimorphism in the Pectoral or Buff-breast. Male Ruffs, however, are not only more brightly colored than females but are individually recognizable.
In 20 of the 24 species of calidridines, sexual dimorphism in body size varies from 0.86 to 1.00, in bill length from 0.85 to 1.00, and in tarsus length from 0.94 to 1.01. In the remaining four species those ratios are, respectively, 1.15, 1.03, 1.06 for C. acuminata, 1.19, 1.08, 1.11 for T. subruficollis, 1.37, 1.08, 1.08 for C. melanotos, and 1.77, 1.15, 1.23 for P. pugnax. In the 20 species with reverse dimorphism, the territorial and courtship displays often involve prolonged aerial flights of some complexity. In the four species with normal dimorphism, there is a reduction in or lack of aerial display and an increase in the degree of polygyny.

Johnson, C. & C. D. T. Minton (1980): The primary moult of the Dunlin Calidris alpina at the Wash. Orn. Scand. 11: 190 - 195.

The primary moult of the Dunlin Calidris alpina at the Wash, East England, is described. A new statistical method for estimating the duration of the moulting period of a population is developed and individual moult duration is also considered, using population parameters and data from retraps. Differences were found in the timing and duration of moult season in different years. Within any one year late moulting individuals moulted more rapidly than early birds. The adaptive significance of these differences within the annual cycle is discussed.

CP:This paper deals mainly with the progression of moult within the population, the authors stating that "...it is expected that a sigmoid curve will fit the data better than a linear model" "...an estimate of the average moul duration for the individual was obtained by considering the median moult scores of the population (Appleton and Minton 1978)." The moulting rate grew from 1.1 in birds caught before 15 July to 1.3 in birds caught 16-31 July and 1.5 in birds caught 1 - 15 Aug, the growth rates gradually fell to 0.7 - 0.8 when birds approached the final stages of moult.

Johnson, C. (1985): Patterns of Seasonal Weight Variation in Waders on the Wash. Ringing & Migration 6: 19-32.

Analysis of weight variation, based on monthly mean weights for ten wader species occurring on the Wash demonstrating the patterns of season weight variation. For each species the trends are interpreted in terms of adaptations and responses to specific life cycle events and potential feeding difficulties which arise from winter environmental conditions.

Jönsson, P. E. (1986): The migration and wintering of Baltic Dunlins Calidris alpina schinzii. Vår Fågelvärld. Supplement 11: 71 - 78. This paper has no abstract.

CP: Jönsson notes that Baltic schinzii arrive earlier and start breeding earlier in spring than British and Irish breeding birds, and he also assumes different wintering grounds, maybe from the Bay of Biscay to Morocco. He suggests (quoting Soikkeli 1967 and referring to own, unpublished material), that there is evidence that 2nd calendar birds breed to a less extent. A survey of first breeding age in arctica, schinzii and alpina populations can be found in Rösner 1997, p. 186.

Jönsson, P. E. (1987): Sexual size dimorphism and disassortive mating in the Dunlin Calidris alpina schinzii in southern Sweden. Orn. Scand. 18: 257 - 264.

In a South Swedish population of Dunlins, males were on average smaller than females. Differences were most pronounced in bill length and body mass. Males arrived at the breeding sites in spring on average 12 days earlier than females, with a tendency for large and long-billed females to arrive earlier than small and short-billed females. A significant positive correlation between date of arrival and start of egg-laying was found in females, but not in males.Previously mated pairs started egg-laying on average 4 days earlier than newly formed pairs. Disassortive mating in relation to size was found in new pairs, so that small and short-billed males, and large and long-billed females nested earlier than average-sized birds. A significant positive correlation was also found between female size and mean egg volume. To explain the observed pattern of mating and sexual size dimorphism, I suggest a combination of sexual and natural (ecological) selection. Small size in males may be energetically advantageous durin aerial display and male parental care. Short bills may be selected for when males are feeding in terrestrial habitats during brood-rearing. In females, selection for large size and long bill is probably associated with the production of larger eggs and more efficient feeding in marine littoral habitats, respectively. Selection may also favour large females in intra-sexual competition for mates and food resources.

CP: I have seen a few unpublished Arctic bill-length distributions as well. Birds are chosen from two bill-length distributions, one male, one female, but are these distributions normal, and if not - why? How will this affect a discussion concerned with "adaptations" - is the mate choice one "adaptation" and the overall character of the bill-length distribution another? Are the schinzii basic distributions normal?

Kania, W. (1990): The primary moult of breeding Dunlins Calidris alpina in the central Taimyr in 1989. Wader Study Group Bull. 60: 17 - 19.

Kaukola, A. & I. Lilja. (1972): Migration of Calidris and Limicola species at Yyteri in 1961 - 69. Porin Lint. Yhd. Vuosikirja 1972: 17 - 23 (In Finnish with English summary).

King, J. R. (1981): Energetics of avian moult. Proc. 17th Int. Orn. Congr. 312 - 317.

Klaassen, M. & B. J. Ens (1990): Is salt stress a problem for waders wintering on the Banc d'Arguin, Mauritania? Ardea 78: 67 - 74.

Kolthoff, G. (1896): Zur Herbstwanderung der nordischen Sumpfvögel über die Insel Öland. Festskrift för Liljeborg, 121 - 136. Uppsala.

Krol, E. (1985): Numbers, reproduction and breeding behaviour of Dunlin Calidris alpina schinzii at the Reda mouth, Poland. Acta orn. 21: 69 - 94.

Kube, J., H.-U. Rösner, H. Behmann, U. Brenning & J. Gromadzka (1994): Der Zug des Alpenstrandläufers (Calidris alpina) an der südlichen Ostseeküste und im Schleswig-Holsteinischen Wattenmeer im Sommer und Herbst 1991. Corax, Sonderheft 2: 73 - 82.

In the late summer and autumn of 1991 migrating Dunlin (Calidris alpina) were counted along the south Baltic coast and in the Waddensea parts of Schleswig-Holstein. In all Baltic areas there were three waves of migrating adults and one wave of migrating juveniles. A sharp rise in Waddensea numbers coincides with the first Baltic wave of adults, a second rise in September with the wave of juveniles. Based on estimates of the maximum amount of resting adults and juveniles along the Baltic shores, and catching results from the mouth of Vistula (Poland) and the isle of Langenwerder, a minimum value for the overall passage of migrant Dunlin in this area can be calculated. Relatively few adults visit German and Polish shores: only 1 - 2 % of the total population, while more than 10 % of the juvenile population stays for some time in the same area.

Kus, B. E., Ashman, P., Page, G. W. et al. (1984): Age related mortality in a wintering population of dunlin. Auk 101: 69-73.

Lane, B. & A. Jessop (1985): Tracking of migrating waders in north-western Australia using meteorological radar. Stilt 6: 17 - 28.

Leslie, R. & C. M. Lessells (1978): The migration of Dunlin Calidris alpina through northern Scandinavia. Orn. Scand. 9: 84 - 86.

Observations made on the Varangerfjord, N.E. Norway, during 1974 indicate that there is a large Dunlin passage through the area. Ringing recoveries suggest that juveniles which pass through the area during August move down the west coast of Norway, whilst adults, moving through during July, take a more easterly route, moving overland to the Gulf of Bothnia and into the Baltic.

CP:This is a stenographic, non-transparent paper, representing the worst of the British tradition (later on in particular: Bird Study) by this time. The suggestions by the authors have been treated as statements when quoted, but none of these statements can be critically assessed. A "juvenile route" along the Norwegian west coast was established here, adults were said to be channeled by way of the Baltic - and all problems, difficulties, complications were swept under the carpet. I would very much like to see juv : ad ratios from the Norwegian west coast, I would like to see figures describing the overall catching period, and I would like to know if this catching period coincides with the migration period of Dunlin in Norway. And: is the age-determination of late Dunlin reliable in the Norwegian case?

Lindström, Å. & T. Piersma (1993): Mass change in migrating birds: the evidence for fat and protein storage re-examined. Ibis 135: 70 - 78.

Lindström, Å., Visser, G. H. & S. Daan (1993): The energetic cost of feather synthesis is proportional to basal metabolic rate. Phys. Z. 66: 490-510.

(...)The cost of feather synthesis was estimated at 836 and 683 kJ per (g dry feathers) in the bluethroats and redpolls, respectively. (...) The Cf for a species with known BMRm may be estimated from the equation Cf = 270BMRm. Species with a relatively high BMRm for their size also have a relatively high Cf. The tight association of Cf and BMRm between species, and the low efficiency values of feather synthesis, suggests that feather production costs include more than the costs for keratin synthesis: they mainly consist of costs of maintaining tissues necessary for feather production.

Martin-Löf, P. (1958): Storleksskillnader hos genomsträckande kärrsnäppor (Calidris alpina) vid Ottenby. Vår Fågelvärld 17: 287 - 301. This paper has a summary, part of it is quoted here.

Measurements of bill, wing, and total length of 1.112 dunlins (99 % juvenile birds of the year) trapped for ringing at Ottenby bird station, on the island of Öland, during three weeks in August and September 1957 show that considerable differences in size exist between birds from the earlier and birds from the later part of this period.
This was demonstrated by splitting the material into three groups, each representing a period of one week: 26 Aug. - 1 Sept. (443 inds.), 2 - 8 Sept. (322 inds.), and 15 - 21 Sept. (347 inds.); no measurements were taken between Sept. 8 and 15. (...) While bill-size proved very uniform between the three groups, there was a small but quite significant decrease in winglength between the first two periods and the last and a very appreciable increase in total length at the same time.
It was evident from the distribution of the measurements - especially the total lengths - that the last group was heterogeneous. For that reason a very late group was picked out of the material, namely 150 birds chosen at random from those trapped 19 - 21 September. Similarly a very early group was selected, namely 150 birds chosen at random from those trapped 27 - 28 August. (...)
The conclusions drawn from the preliminary analysis are further strengthened by this treatment. There is a remarkable conformity in bill-length between early and late birds. The frequency distribution of measurements in each group is close to normal, which indicates that the difference in bill-length between the sexes, known from museum studies on the Dunlin, is not very pronounced in the present material of young birds. The wings of August birds are about 3 mm longer on the average than those of September birds (and this difference) is highly significant. Etcetera, etcetera.

CP: This is an old paper, an antique. What I like about it is the fact, that it is transparent; the conclusions can be checked, this is not always the case when it comes to papers based on Ottenby material. The sampling intervals seem a little "forced", but there is no way telling if this also lies behind the "non-committal" of the conclusions. What everybody would like to see from Ottenby is large, coherent materials - moult, biometry - covering the whole of the migration period, without any kind of calendar compulsion or possible influence from measuring techniques.

Mascher, J. (1966): Weight variation in resting Dunlins (Calidris a. alpina) on autumn migration in Sweden. Bird-Banding 37: 1 - 34. This paper has a long summary, I choose to quote points 2, 4 and 5.

2. As is clear from the recapture figures, the passage proceeds much faster early in the season than later. In 1963, only 14.5 per cent of the adults were retrapped as compared to nearly 30 per cent of the later-arriving juveniles. Very few adults stayed more than 2-3 days, whereas 18.3 per cent of all recaptured juveniles lingered more than 8 days. (...)
4. An increase in total weight of 0.50 gm per mm wing length was found in the juveniles. This is appreciably more than the figures applying to medium-sized and larger passerines. In adult Dunlins, a somewhat smaller increase amounting to 0.41 gm per mm wing length was found, but the difference is barely significant.
5. The lowest weight records obtained were probably near the fat-free weight of the subspecies C. a. alpina, which is likely to average about 34-35 gm. Some fat-free data on the larger sakhalina subspecies averaged about 5 gm more than the fat-free weight calculated for the corresponding wing length in C. a. alpina. The maximum fat deposition in Dunlins resting at Ledskär amounted to 20-25 gm fat or 40 per cent of total body weight, which is in accordance with data published on passerine migrants.

Mascher, J. & V. Marcström (1976): Measures, weights, and lipid levels in migrating Dunlins Calidris a. alpina L. at the Ottenby Bird Observatory, South Sweden. Ornis Scand. 7: 49 - 59.

Measurements, weights, and lipid levels of 85 Dunlins collected during two autumn seasons at the Ottenby Bird Observatory in South Sweden were analyzed. Males had significantly shorter wings and bills, and lower body weights than females. Fat depots ranged from about 5 to 30 per cent of total weight an accounted for the major variations in body weight. No correlation was found between body size and lipid level. The water content expressed as a percentage of fat-free weight was virtually constant within each year sample, irrespective of body size and lipid level. Significant differences in fat-free dry weights and water content between the two year samples were found. A formula for calculation of fat stores from total weight and wing length is presented. The results are compared to other work on waders and passerines.

McEwan, E. H. & P. M. Whitehead (1984): Seasonal changes in body weight and composition of Dunlin (Calidris alpina). Can. J. Zool. 62: 154 - 156.

McNeil, R. & F. Cadieux (1972): Numerical formulae to estimate flight range of some North American shorebirds from fresh weight and wing length. Bird-Banding 43: 107 - 113.

Meissner, W. (1998): Fat reserves in Dunlins Calidris alpina during autumn migration through Gulf of Gdansk. Orn. Svec. 8: 91 - 102.

To describe fat reserves in adult and juvenile Dunlins during autumn migration in the Gulf of Gdansk, multiple regression equations for estimating fat mass in Dunlins were derived. The average fat level in a particular wave of migrants depends on many factors. Low amount of accumulated fat suggests that this species migrates along the southern Baltic in small steps, similarly to the rest of Europe. The interpretation of the results is difficult because at least two distinct migration routes cross the Gulf of Gdansk region. Dunlins starting their primary moult had lower fat index than birds in advanced stages of moult. The rate of fattening in Dunlin depends on the quality of the feeding place (higher in the sewage farm than in the river estuary). Birds which stayed longer in the feeding area had, on average, lower fat mass increments than those leaving Gulf of Gdansk after a short stay. Birds with low fat mass started putting on weight immediately, whereas "fat" birds lost weight at the beginning. Those results confirmed Mascher's (1966) hypothesis about differences in body mass change rate during the first day of stay in birds with low and high fat reserves. The level of free fatty acids in the blood appears to be a factor controlling this pattern. Differences in fat accumulation between Ottenby (southern Sweden) and Gulf of Gdansk are discussed.

CP: 426 out of 8443 = 5.0 % Dunlins caught at Rewa and 140 out of 1685 = 8.3 % at adjacent Jastarnia had scores 49 - 50 (i.e. complete wing). In all, 5.6 % of all adults passing the Rewa area had performed a complete moult on or near breeding-grounds, they migrated with fresh remiges. And these completely moulted adults accompany juveniles, in Poland till the catch is ended prematurely in late September, in the Sound area until the last migration waves in October. I do not expect anyone to suggest seriously, that the Polish birds had returned from moulting grounds in the Waddensea. (I had this suggestion in connection with late adults at Langenwerder). This note is saved here for reference.

Also note the remark: Data from birds retrapped in the Rewa region show that many are in active moult (unpublished data), as occurs on the Swedish coast (Holmgren et al. 1993). This is the same vague way of self-quotation as in Holmgren et al. 1993b! I have a question here: Catches reveal different stages of moult at Rewa - but what do retraps show? A score of adults has rested for more than a week. This material could be very important - but is it conclusive?

Meltofte, H. & J. Rabøl, (1977): Vejrets indflydelse på efterårstrækket af vadefugle ved Blåvandshuk, med et forsøg på en analyse af trækkets geografiske oprindelse. DOFT 71: 43-63.

Meltofte, H. & P. Lyngs, (1981): Spring migration of waders Charadrii at Blåvandshuk, Western Denmark, 1964-1977. DOFT 75: 23-30. Excerpt from the summary.

(...)In Limosa limosa and Calidris alpina, together with more usual occurrences of Calidris canutus, the main part of the movements pass south, and mainly in the morning hours. This migration is probably made up of birds passing the southern part of the North Sea on their way to the northern part of the Wadden Sea. Most birds are seen in southerly winds and low visibility, thus probably having drifted a little north during the passage.
In Haematopus ostralegus, Limosa lapponica and Calidris alpina two distinct peaks are seen during spring. It is concluded that these are made up of different populations. (...) In Limosa lapponica and Calidris alpina they may be populations having wintered in West Europe and West Africa, respectively, and which arrive in the Wadden Sea at different times, the African wintering population arriving later than the European wintering birds.

Meltofte, H. (1993): Vadefugletrækket gennem Danmark. DOFT 87: 1 - 180. Short excerpts of the Dunlin text are quoted here.

p. 66: It is not possible to separate the migration of European and Siberian birds, but as the migration culminates c1 week earlier in SW Finland, at Ottenby and S. Amager (Copenhagen, Sealand) than at Blåvand (W Jutland) (Fig. 23; Edelstam 1972, Kaukola & Lilja 1972), it is probable, that North European breeding birds migrate a little earlier than Siberian. Wader migration at Blåvand generally has a higher share of Arctic populations than Baltic sites (Meltofte & Raböl 1977). And the ringing material from the Dutch Waddensea indicates, that European breeding birds to a higher extent migrate by way of the Baltic (Goede et al. 1990).
p. 70: During the culmination of juvenile migration, in September-October, some 250000 - 350000 Dunlin are regularly present in the Danish part of the Waddensea, and occurrances exceeding 400000 have been noted twice. These are very high numbers compared with the remaining parts of the Waddensea, and the same applies to spring, The maximum number in Schleswig-Holstein is 300000, in Niedersachsen 290000, in Holland 274000 (Smit & Wolff 1981, Zegers & Kwint 1992, J. Blew and H.-U. Rösner in litt.) In other parts of Denmark some 40 - 50000 birds are resting during the same period.

Meltofte, H., J. Blew, J. Frikke, H.-U. Rösner & C. J. Smit (1994): Numbers and distribution of waterbirds in the Wadden Sea. Results and evaluation of 36 simultaneous counts in the Dutch-German-Danish Wadden Sea 1980-1991. IWRB Publication 34, WSG Bulletin 74, Special issue.

(from text) Our mid-winter counts have yielded totals of between 131,000 and 258,000 during mild winters. Of these, up to 210,000 have actually been counted. Considerably less Dunlins remain during severe winters, when we recorded between 23,400 nd 62,200. In mild winters, the Dunlins are surprisingly evenly distributed throughout most of the Wadden Sea, where they predominantly feed on silty flats (Ens et al. 1993). In severe winters, the Danish, German, and eastern parts of the Dutch Wadden Sea are largely deserted. In January 1992 a record 78,000 Dunlins were found in the Schleswig-Holstein Wadden Sea (Rösner unpubl.).
In spring, large numbers of Dunlins start to move into the Wadden Sea from late February onwards. These are birds that have wintered further west and south in Europe, which go to the Wadden Sea to moult into breeding plumage and build up body reserves for the onward migration. Numbers increase in most areas during March and April, until a new influx of birds apparently takes place in early May. There are indications that the Dunlins arriving in March and April are European sub-arctic breeders, while those passing in May breed in Siberia (Goede et al. 1990, Meltofte 1993). Acording to our counts, more than 4000,000 Dunlins may be present in the Wadden Sea already by March. Numbers increase to between 804,000 and 1,120,000 during our best counts in the first half of May, when birds from the whole breeding range are supposed to be present. Of these up to 1,046,000 Dunlins were actually counted. With 50,000-100,000 Dunlins staging in other parts of Denmark and 15,000-35,000 in the Dutch Delta (Meininger & van Haperen 1988, Meininger et akl. 1994), this means that up to about 90 % of the West European/West Mediterranean alpina Dunlins could be present in the Wadden Sea countries at this time. As some hundreds of thousands may fly north via South-east Europe and the Black Sea in spring (Meltofte 1991, 1993), this may merely point to an underestimation of the population, however. Wadden Sea numbers decrease during mid and late May, when first the European sub-arctic breeders and then the arctic breeders leave for their breeding grounds. (...)

Ming, S. & L. Jianjian (1992): The dynamics of body composition of overwintering Dunlin Calidris alpina sakhalina. Wader Study Group Bull. 64: 35-36.

Minton, C.D.T. (1975): Waders of the Wash - ringing and biometric studies. Rep. Sci. Study Group of the Wash Water Storage Scheme.

Müller, S. (1985): Bemerkenswerte avifaunistische Beobachtungen aus Mecklenburg. Orn. Rundbr. Mecklenb. 28: 68-96.

Nieboer, E. (1972): Preliminary notes on the primary moult in Dunlins Calidris alpina. Ardea 60: 112-119. A Dutch pioneer paper, fieldwork at Schiermonnikoog in 1968 and 69, no summary.

Nörrevang, A. (1955): Rylens (Calidris alpina (L.)) traek i Nordeuropa. DOFT 49: 18 - 49.

(...)No doubt some of the Dunlins observed in southern Sweden - Norway and in Denmark come from northern Scandinavia, but studies at Jæren indicate that many of the birds come from northern Russia and Siberia. The Taymyr peninsula probably acts as a sort of migratory divide. One bird with bill 38 mm no doubt comes from Western Siberia.
Mr HOLGER HOLGERSEN tells (in litt.) that a bird ringed at Jæren on Sept. 22nd, 1950, was recovered from the Yamal Peninsula in northwestern Siberia in June 1951.
The populations of Russia and Siberia must migrate WSW along the northern coast of Russia. However, some birds probably go due south (inland migration has been observed) but they will hardly touch Europe. At Rossitten there were large birds, too, probably coming from West Siberia also. These birds must have passed the Onega-Ladoga lake-district (PALMÉN'S migration route).
The Öland birds may have come from the Estonian islands of Hiiumaa and Saaremaa as the migration is partly west-bound. No doubt these birds have come there by the same route as those migrating along the southern limits of the Baltic.
South-directed birds (transversing the inland of Central Europe): From Rossitten 33.3 per cent, from Öland 9.3 per cent and from Amager 5.0 per cent. Birds from Jæren going south will be led along the western coast of Jutland. Still, one bird was recovered in Zealand(...).
No strong migration should be expected at Jæren, but nevertheless it is very strong. Some of the birds cross the North Sea, but many of them go straight south and are recovered in Denmark (10.6 per cent). There may be two causes for this, viz.: 1. North-Scandinavian birds going south cross the migration route of eastern birds going southwest. 2. There is a regular deviation of the birds going SW so that they for some reason are pushed northwards. From Jæren they either continue in the old migration-direction or they try to find again the old migration route by going S.
It speaks for the second suggestion, that ten birds ringed at Jæren were recovered at Öland in later years, and two recorded at Amager. Only one bird ringed at Öland was recovered at Jæren in a later season.

OAG Münster. (1976): Zur Biometrie des Alpenstrandläufers (Calidris alpina) in den Rieselfeldern Münster. Die Vogelwarte 28: 278 - 293. (Biometry of Dunlins in the Sewage Farms of Münster.)

1. From 1969 on to 1975 331 Dunlins were caught and measured in the sewage farms of Münster, 13 of them in the home-migration period. In the off-migration period only 12 adults were ringed. Therefore this study mainly deals with juvenile birds.
2. The frequency distribution of wing lengths corresponds approximately to a normal distribution, in contrast to the bimodal distribution of bill lengths. According to these measurements by far the greatest part of the birds caught belongs to the nominate race, fewer individuals to the race C. alpina schinzii and very few probably to C. alpina sakhalina (about 3 cases).
3. The pentade mean values of wing and bill lengths show a distinct downward trend throughout September and October.
4. The standardized weights yield a normal distribution; the mean weight is quite high in comparison to dates from literature. The pentade mean values of weight do not demonstrate clear changes throughout the off-migration period. The changes of weights of recaptured Dunlins scatter very much and do not show a trend.
5. Correlations between various measurements are statistically highly significant.
6. 20 % of juvenile Dunlins were found moulting body feathers and wing coverts.

Page, G. W. (1974): Age, sex, molt and migration of Dunlins at Bolinas Lagoon. West. Birds 5: 1 - 12.

Pettersson, J. (1994): Ottenby fågelstation 1993, in: SOF 1994. Fågelåret 1993. Stockholm.

Pienkowski, M. W. & W. J. A. Dick (1975): The migration and wintering of Dunlin Calidris alpina in north-west Africa. Orn. Scand. 6: 151 - 167.

The numbers of Dunlins present during the year on the coasts of north-west Africa are summarised. Information on timing of migration, ringing recoveries, and analysis of bill lengths is used to determine the geographical origins of these birds. Most individuals are from the breeding populations in southern Scandinavia, western Europe, and Iceland, so that Morocco and Mauritania are of unique importance to these populations in the non-breeding season. There is some overlap in Morocco with populations from the northern Eurasian breeding grounds whose main wintering area is further north in Western Europe. The north-west African birds migrate in short flights without putting on large fat reserves. Many birds moult their primary feathers during migration.

Pienkowski, M. W. (1976): Recurrence of waders on autumn migration at sites in Morocco. Vogelwarte 28: 293 - 297.

Pienkowski, M. W., Knight, P. J., Stanyard, D. J. & F. B. Argyle (1976): The primary moult of waders on the Atlantic coast of Morocco. Ibis 118: 347 - 365.

(...)Similar rates of primary feather replacement relative to specific moult duration were observed in all species for which information was available. Comparisons between species and with published studies showed that variations in rate of moulting between species and between different geographical populations of the same species were largely due to differences in feather growth rate rather than in the number of primaries concurrently in growth. Variations in rate between individuals of the same population were achieved, at least in the first part of moult, by differences in feather dropping rate resulting in differences in the numbers of primaries growing concurrently.
(...)Most Redshank and possibly Dunlin migrated in active wing moult.

Pienkowski, M. W., Lloyd, C. S. & C. D. T. Minton (1979): Seasonal and migrational weight changes in Dunlins. Bird Study 26: 134 - 148.

In eastern England, Dunlin weights peak in December. Is this because food is abundant then, or an 'insurance' against cold weather to come? Such early winter weight peaks do not occur in south-western Britain and the implications of this are discussed.

Pienkowski, M. W. & P. R. Evans (1984): Migratory behaviour of shorebirds in the western Palearctic, pp. 73 - 123 in: J. Burger & B. L. Olla: Behavior of Marine Animals. Vol. 6, Shorebirds: Migration and foraging behavior. Plenum Press, New York.

Piersma T. & N. E. van Brederode (1990): The estimation of fat reserves in coastal waders before their departure from Nortwest Africa in spring. Ardea 78: 221 - 236.

To derive realistic equations for evaluating the fat loads of waders before their departure from NW Africa in spring, we have analysed samples of waders inadvertedly killed during catching operations in Morocco, Tunisia and Mauritania. We studied the relationships between body and fat mass and structural size variables. Part of the original variation in body mass was attributable to a constant relative water loss between capture and first weighing, and body mass values used in the consequent analyses were corrected accordingly. In the four species for which large samples were available (Knot, Little Stint, Dunlin and Redshank), linear regression of fat mass on body mass indicated that 50 - 60 % of the differences in individual body mass is due to differences in the total fat mass. In all four species wing length correlated well with lean mass, suggesting that this dimension is generally a better structural variable than total head, bill and tarsus plus toe length. Only in Dunlins, bill length correlated best with lean mass. Multiple regressions with fat mass as the dependent variable and body mass and structural size variables as independent variables, showed that only those dimensions which correlated with lean mass, contributed significantly to the explained variance in fat mass in addition to body mass. An alternative regression model in which body mass was estimated from fat mass and structural size variables and then reformulated, did not lead to improved predictive equations. The suggested equations to estimate fat mass in individual Knots, Little Stints, Dunlins and Redshanks allows the estimation of fat mass of the heaviest birds with an accuracy of ca 30 %, but with a much lower accuracy in light birds (all estimated values within 100 % from the true value).

Pitelka, F. A., Holmes, R. T. & S. F. Maclean (1974): Ecology and Evolution of Social Organization in Arctic Sandpipers. Amer. Zool. 14: 185 - 204.

A comparative analysis of sandpiper social systems on arctic and subarctic breeding grounds (24 species in the family Scolopacidae, subfamily Calidridinae) shows four major patterns. In a majority of the species (15), populations are dispersed through a strongly developed territorial system, with strong monogamous pair bonds and only minor yearly fluctuations in numbers. The second pattern isseen in three species in which the female of a pair may lay two sets of eggs in quick succession, one for each member of the pair to incubate. This opens opportunities for facultative polygyny or polyandry ('serial polygamy') and for the evolutionary weakening of the strong pair bond seen in the first pattern. The third and fourth patterns are those of polygyny (three species) and promiscuity (three species). These six species show clumped dispersions; their year-to-year fluctuations tend to be strong; the males defend compressible, often small, territories; and high densities can occur locally. It is suggested that the pattern of overdispersion and monogamy represents a conservative mode of adapting to high-latitude environments, while the pattern of clumped dispersion with polygyny or promiscuity represents an opportunistic mode in that the birds are concentrated into breeding areas where and when weather, food, and/or some other environmental factors are particularly favorable. Apparently falling evolutionarily between these two basic patterns are several species conservative in their life-styles, but polygamous at least occasionally and showing some features of opportunism. There is thus a striking diversity of social systems in calidridine sandpipers, that is, in the styles of habitat exploitation they have evolved in the arctic and subarctic habitats to which their breeding is confined. A graphic model suggesting paths of evolutionary development and of interplay among factors considered critical in the evolution of these systems is proposed.

Remisiewicz, M. (1996): Influence of weather conditions on the autumn migration of Dunlin (Calidris alpina) at the southern Baltic coast. The Ring 18: 73 - 88.

Roos, G. (1962): Vinterfåglar på Falsterbonäset. Fauna och Flora 57: 249 - 273.

Roos, G. (1984): Flyttning, övervintring och livslängd hos fåglar ringmärkta vid Falsterbo (1947-1980). Anser, Supplement 13. Lund 1984.

Ruiz, G. M., Connors, P. G., Griffin, S. E. & F. A. Pitelka (1989): Structure of a wintering Dunlin population. Condor 91: 562 - 570.

Rösner, H.-U. (1990): Sind Zugmuster und Rastplatzansiedlung des Alpenstrandläufers (Calidris alpina alpina) abhängig vom Alter? J. Orn. 121 - 139. (Are there age dependent differences in migration patterns and choice of resting sites in Dunlin Calidris alpina alpina?)

The Dunlin is the most numerous wader species in the whole Wadden Sea. It uses the area mainly for fattening in spring and for moulting in late summer. In the Wadden Sea a very strong site fidelity in adults was found. The same is true in the British estuaries, which are the main winter quarters. This allows the adults to develop a good knowledge of local conditions in the comparatively few areas used. In contrast to the adults, juveniles on autumn migration stop at more places and stay longer at each. They also use sites where only a very few adults are seen. Results of catching and counting in the Wadden Sea suggest that competition between adults and juveniles influences the dispersion of juveniles. To explain these phenomena, a hypothesis on migration patterns is presented. It is suggested that juveniles start their first autumn migration by taking only a rough general direction without aiming to reachparticular resting sites. They probably find these by trial and error, visiting only suitable sites again in the following years. Therefore juvenile Dunlins should discover newly arisen sites very quickly and may even fill them up. They should not stay at those sites which decrease in quality, so these sites will loose numbers in spite of high site fidelity of adults. The hypothesis could also help to explain results which are so far assumed to be caused by the occurrence of different subpopulations.

CP: This is a speculative paper, and I think I see the "epistemological" elements of its structure: a thought construct reified into reality. Under normal circumstances this course might be quite legitimate, but if the justification fails - if only to some extent - the speculator is in trouble. He must make exceptions, and these exceptions start a landslide. Rösner's model holds as long as it is not discussed.

Rösner, H.-U. (1997): Strategien von Zug und Rast des Alpenstrandläufers (Calidris alpina) im Wattenmeer und auf dem Ostatlantischen Zugweg. Aachen 1997. (Strategies of staging and migration of Dunlin in the Wadden Sea and along the East-Atlantic Flyway).

2. In the Wadden Sea, Dunlins are the most abundant bird species. Reaching counts of at least 1.2 million, almost all individuals of the West European wintering population can occur here at the same time. In the Schleswig-Holstein part of the Wadden Sea (SHW), numbers up to 600,000 were reached. Compared to other species, Dunlins are spread evenly across the SHW. They are present year-round, reaching their highest numbers from August to October and in April/May and very low numbers in June. During normal winters 10-20 % of the population are present in the SHW, during ice winters 2-4 %.
3. Among the staging areas, short-term and long-term can be distinguished. Along the Baltic coast there are numerous short-term staging areas. The waves of migration observed correspond well with the seasonal phenology in the long-term staging area SHW. Ringing recoveries also show that a large proportion of the SHW Dunlin regularly migrate along the Baltic coast.
4. The coasts of Great Britain and Ireland are the most important wintering area for SHW Dunlins. The south-western Wadden Sea, the Rhine Delta and the French and Portuguese Atlantic coast are also visited. Only a few individuals reach the Mediterranean Flyway and, possibly, Africa.
5. The breeding origin of SHW Dunlins includes mainly the tundra areas from northern Scandinavia to the Yamal Peninsula or just east of it. Birds from Taimyr do not, or only exceptionally, reach the SHW. A considerable fraction of the small Baltic breeding population also stages in the SHW. There is no indication for birds of Nearctic origin. These results were reached mainly by colour-ringing on the breeding grounds; morphometric and genetic studies added to the picture.
6. Dunlins are highly site-faithful not only to breeding areas but also to their natal areas and to staging areas. SHW birds are, over many years, observed almost exclusively in the same staging areas; only few also visit other areas within the Wadden Sea.
7. Juveniles leave the breeding area later than adults and use partially different migration routes and short-term stopover areas. Even in the long-term staging area they initially hardly mix with adults and, even months later, still show a different distribution from that of the adults. This can be explained mainly by lack of experience, especially concerning predators. An effective mechanism for displacement of juveniles by adults could not be found. Proportions of juveniles are larger in the south-western than in the north-eastern Wadden Sea, probably because of differences in migration routes.
8. The characteristic features of juvenile migration hold one key to understanding the migration system and patterns of use of staging areas in Dunlin. Newly emerging areas can be settled quickly by juveniles. At the same time, areas with high hunting pressure (such as, perhaps, France) can act as a sink for juveniles.
9. By combining juvenile data from many short- and long-term staging areas, an index for the population-wide annual breeding success since 1948 is created. It shows a weak three-year cycle and some correlations with the breeding success of other arctic-breeding bird species. Fluctuations in Dunlin breeding success are smaller than in other species, probably because of the wide range and less extreme breeding conditions of Dunlin.
10. For the period since 1970, data from numerous areas are combined to a 'flyway index' for the western European wintering population, which numbers from 0.9 to 1.5 million birds. Periods of stable or increasing population numbers were interrupted by a ten-year period of low numbers. Unusually high mortality in the breeding areas in some years, fluctuation in production of young and ice winters majorly influenced the population development. The general increase in numbers probably started already before 1970, following very low population levels due to hunting mortality in the first half of this century.
11. On a large spatial scale, birds from diferent breeding areas are separated according to their migration times and routes. On a smaller scale, e.g. within the Wadden Sea, the characteristics of juvenile migration largely preclude a spatial separation of birds of different breeding origin. The temporally separate migration of Baltic birds is an exception here. The birds of northern breeding origin mix to a large extent; their timing of spring migration varies gradually according to the onset of breeding which varies by about one month across the climatic zones of the breeding area.
12. Within the range of the species, different life history strategies can be found. Birds breeding in the Baltic, Great Britain and Ireland tend to be limited by breeding habitat and have abundant survival habitat, whereas the opposite is true for birds from Northern Scandinavia, western and eastern Siberia and northern Alaska.
13. At least in the past, the size of the western European wintering population was determined by hunting. The limiting factors at present are less certain, nor is it clear whether the long-term increase in population numbers is still continuing. On the West Pacific and Mediterranean Flyway, hunting is probably threatening populations at present; on the East Atlantic Flyway, primarily the very small breeding populations are endangered. For the future, an 'integrated population monitoring' of arctic waders is proposed; this is explained for the example of Dunlin on the East-Atlantic Flyway.

SkOF. Fåglar i Skåne. Anser, Suppl. (1975-1993): (Annual Report from Scania).

Smit, C. J. & W. Wolff (eds.) (1981): Birds of the Wadden Sea. Report 6 of the Wadden Sea Working Group. Balkema, Rotterdam.

Smit, C. J. & T. Piersma (1989): Numbers, mid-winter distribution and migration of wader populations using the East Atlantic Flyway. IWRB Special Publ. 9: 24 - 63.

CP:The maximum number of Dunlin recorded on the East Atlantic Flyway, 2.2 million, was stated in this publication.

Smith, K. W., Reed, M. J. & B. E. Trevis (1999): Nocturnal and diurnal activity patterns and roosting sites of Green Sandpipers Tringa ochropus wintering in southern England. Ring. & Migr. 19: 315 - 322.

A radio telemetric study of Green Sandpipers at their wintering site, a disused watercress bed in southern England, shows that they alternate between the watercress bed and a nearby gravel pit complex over the course of the autumn and winter. Birds spent most days feeding at the watercress bed and roosted overnight in the gravel pit complex. During extremely cold weather in January and February the birds switched to roosting at the watercress beds. Automatic activity monitoring showed that the birds were active for around 80 % of each day at all times of year. Their time active at night varied from around 16 % in autumn to over 40 % in cold conditions in midwinter. The hours the birds were active during the day and night in mid-winter were inversely proportional to the maximum daily temperature. The evidence suggests that a low level of night time activity is normal in Green Sandpipers but the high levels found during extremely cold winter conditions are the result of birds attempting to increase their daily food intake thus supporting the 'supplementary' hypothesis for nocturnal foraging.

SOF. Sveriges fåglar. (1990): 2:a uppl. Stockholm. (Swedish check-list).

Soikkeli, M. (1966): On the variation in bill- and wing-length of the Dunlin (Calidris alpina) in Europe. Bird Study 13: 256-269.

The present study deals with variation in bill- and wing-length of Dunlin in a population breeding in western Finland, and also with that appearing in the fairly large material obtained during migration at the Ottenby Bird Station, Sweden. A new method is described for distinguishing between males and females by plumage.
The population breeding in western Finland belongs to the race schinzii,in which the mean bill-lengths are 27.8 mm in males and 31.7 mm in females, and the mean wing-lengths 108.5 and 112.6 mm, respectively.
The material measured during migration at Ottenby consists mostly of Dunlin of the nominate race, in which the mean bill-lengths are 31.4 mm in males and 35.2 mm in females.
It is considered very improbable that there should be any intergradation between alpina and schinzii in northern Sweden, as claimed by Swedish workers. The Dunlin of the nominate race breeding in northern Scandinavia may however have shorter bill- and wing-lengths than other populations of alpina. (...)

CP: I spent some time studying Fig. 5 of this paper: "correlation of bill-length with wing-length in the Dunlin population breeding in western Finland". According to the paper there are 96 male and 71 female bill-lengths, 56 male and 49 female wing-lengths. Plotted in the figure are c96 male and c65 female bill-lengths - but how were these correlated with wing-lengths if there were fewer measurements of this kind? There is something fishy about the skewness of the male component distribution.

Stanley, P. I. & C. D. T. Minton (1972): The unprecedented westward migration of Curlew Sandpipers in autumn 1969. Brit. Birds 85: 365 - 380.

The unprecedented influx of juvenile Curlew Sandpipers Calidris ferruginea in Britain and Ireland during late August and early September 1969 is analysed with counts from over 250 localities, these amounting to more than 19,000 bird-days. The principal arrivals took place on 23rd and 26th August, and at the peak on 31st at least 3,500 were present, over 72 % of the records coming from the east coast of Britain.(...)An analysis of all available ringing data indicates a regular autumn migration route through the Baltic and down the Continental seaboard to Africa, some taking a more direct line back across the central Mediterranean in spring. The exceptional influx in 1969 appears to have been due to a migration unusually far to the west, this being caused by abnormally persistent cyclonic weather systems centred over the Baltic and north Russia coinciding with the departure of juvenile Curlew Sandpipers from their breeding grounds. There is some evidence, too, that in 1969 the species had had a successful breeding season.
Weight data indicate that the resting migrants were increasing their weight at up to 7 % per day and calculations suggest that most of them accumulated sufficient fat reserves in seven to ten days to fly direct to north Africa; these estimates are compatible with the rapid decline in total numbers during September. (...)

Stiefel, A. & H. Scheufler (1989): Der Alpenstrandläufer. Neue Brehm-Bücherei, nr 592. Wittenberg Lutherstadt: A. Ziemsen Verlag. A few excerpts from the text quoted here.

Stresemann, E. & V. (1966): Die Mauser der Vögel. J. f. Orn. 107, Sonderheft.

CP:Stresemann's recording "style" in translation, the bird must be a pacifica since it is moulting on breeding-grounds:
28. Aug. 1880, male, Alaska: St Michael - (followed by registration number of museum specimen). P 1 to 8 new, 9 g 3/4, 10 g 1/2 -- Almost fresh winter plumage, only a few black feathers left on belly.

Summers, R. W., R. L. Swann & M. Nicoll (1983): The effects of methods on estimates of primary moult duration in the Redshank Tringa totanus. Bird Study 30: 149 - 156.

The duration of primary moult of Redshank was estimated from various methods involving drawing straight and curved lines through a scattergram of points. Estimates ranged from 72 to 109 days. The growth of the primaries was not constant, so linear regression analysis did not fit the best line to the data, even when the curving effect of describing moult in terms of moult scores was corrected for. Linear regression analyses also gave unrealistically early values for the start and completion of moult. More satisfactory methods involved drawing a curved line through the mean dates for each moult score, or each 5 % of feather mass grown. An even spread of records (nonmoulting plus moulting birds) through the moulting season is essential to give a good estimate of duration.

Swann, R. L. & B. Etheridge (1996): Movements of waders to and from the Moray Firth. Ring. & Migr. 17: 111 - 121.

Tomkovich, P. & L. Serra (1999): Morphometrics and Prediction of Breeding Origin in some Holarctic Waders. Ardea 87: 289 - 300.

Tomkovich P.S., E. G. Lappo & E. E. Syroechkovski Jr (2000): Ringing and migratory links of Taimyr waders. Heritage of the Russian Arctic. Research, Conservation and International Co-Operation. Proc. of the Int. Sc. Willem Barents Memorial Arctic Conservation Symposium held in Moscow, 10-14.3.93: 458 - 474.

Ringing of waders in the Taimyr Autonomous Okrug (district), Northern Siberia, dates back to the 1960's. In 1989-1996, a total of 5,700 waders of 24 species were ringed and some were additionally colour-marked as one of the activities of the International Arctic Expedition organised by the Institute of Ecology and Evolution, Russian Academy of Sciences. Forty-six recoveries of 11 species have so far been obtained including 15 birds marked on the Taimyr Peninsula and 31 ones ringed elsewhere. The highest recovery rate was that in marked Red Knots (Calidris canutus). Indeed, 2.6 % of the 312 birds ringed at the breeding grounds were recovered during the study. Marking Little Stints (Calidris minuta) turned out to be least efficient, no recovery having been obtained despite the most extensive ringing of these birds (over 1,700 individuals). Curlew Sandpipers (Calidris ferruginea) breeding on the Taimyr Peninsula were shown to have the broadest winter distribution range which encompasses western and south-eastern Europe, South Africa, the Indian subcontinent and Australia. It is concluded that the geographic position of Taimyr in the centre of northern Siberia, its wide and diverse expanses of open marshy habitats, and geological history of the peninsula are collectively responsible for its paramount importance for the reproduction of many wader species using different migratory routes.

Underhill, L. G. & A. Joubert (1995) Relative masses of primary feathers feathers. Ring. & Migr. 16: 109 - 116.

A knowledge of the relative masses of the primary feathers is necessary to compute the percentage of feather mass grown by a bird moulting its primaries, as a step towards estimating the parameters of moult using the Underhill-Zucchini moult model. Also, wing shape characteristics can be described by fitting a polynomial regression model to the relative feather masses. This paper presents relative feather mass data for 38 species, primarily southern African. Further data are required to evaluate the concept of fitting mathematical models to describe wing shape.

Wenink, P. W. (1994) Mitochondrial DNA sequence evolution in shorebird populations. Dissertation. Wageningen 1994.

A few excerpts from the summary (references excluded):"(...)There are several reasons why mtDNA is the molecule of choice to probe the recent evolutionary history of a species. Most importantly, mtDNA accumulates substitutions at a high average rate that permits the tracing of genealogies within the time frame of speciation. The population structure of shorebirds, like that of arctic-breeding waterfowl, must have been influenced dramatically by the Pleistocene glaciations (mainly during the last one million years). The fastest evolving part of the mtDNA genome, the non-coding control region, offers sufficient genetic resolution to reveal differentiation of such recent origin. The typical mode of maternal inheritance, the absence of recombination, end the presumed neutrality of substitutions, are characteristics that add to the suitability of mtDNA for the construction of robust phylogenies.
(...)The dunlin, on the other hand, became divided into several isolated populations during the Pleistocene and has retained a significant amount of intraspecific genetic diversity until the present.
(...)A genealogical tre relating (35 different genotypes) revealed five major clusters. Each cluster has high geographic specificity. The cluster containing the most divergent sequences is present along the Atlantic coast of North America and represents the dunlin population breeding in arctic central Canada. Two clusters of genotypes are located principally in western Europe and central Siberia. Evidence for a low level of gene flow between these latter two populations was provided by three individuals whose genotypes suggested they were immigrants. Two other clusters are found along the Pacific coast of North America.(...)
A plausible scenario for the genetic divergence of the major dunlin lineages is the ancestral fragmentation of populations over tundra refugia, that were created by the extensive glaciations of the northern hemisphere during the Pleistocene. Prolonged isolation of populations of reduced size increased the effect of genetical drift and this may have led to the observed mtDNA monophyly. The different lineages continuously diverged by the process of mutation. This ancient subdivision has been retained after retreat of the icesheets, most likely as a result of the strong site-fidelity of dunlins to their breeding ground. [CP: Fidelity to wintering grounds and maybe equally to resting and staging grounds not included here!] Dunlin populations could thus not become homogenized genetically because gene flow is not extensive enough between them.
(...)Phylogeographic groups can be correlated to the global geography of morphometrically defined subspecies in the dunlin. Whereas several disputed subspecies gain support from the genetic data (i.e. C. a. hudsonia in central Canada and C. a. centralis in central Siberia), other subspecies merge into the same phylogeographic group. No major phylogenetic divisions are apparent among the morphometrically dissimilar populations in north-eastern Greenland, Iceland, the Baltic Sea, and Norway (recognized until now as three to four different subspecies). Gauged by the depth of the other phylogenetic splits in dunlin, they can jointly be referred to as C. a. alpina.(...)
It is thus revealed how morphology lacks an evolutionary perspective in the determination of intraspecific taxonomy. (My emphasis; CP) For the dunlin, a parallel morphological evolution of genetically divergent populations, as well as the opposing process of morphological divergence of evolutionary closely related populations, is observed. Morphometric characters employed in intraspecific avian taxonomy are suffering from homoplasy, either as a result of character plasticity and environmental induction, or because of very high mutation rates and strong directive selection acting on phenotypes. Because morphometrically different dunlin populations are often mixed outside the short breeding season, environmental induction of morphology seems unlikely, although this possibility remains to be investigated."

CP:This boils down to two alternatives: genetically defined "haplotypes" (the individual maybe breeding in the main area of another haplotype) and morphologically more or less well-defined "population groups". In the field we can only discern the latter groups, and the aim of the field-worker must be to obtain maximum morphological differentiation, using all characters available. It seems to me, Dunlin are not very "mixed" outside the breeding season - they know their kin, always know their kin and seek it.

Wenink, P. W. & A. J. Baker (1994): Mitochondrial DNA lineages in composite flocks of migratory and wintering Dunlins (Calidris alpina), in: Wenink 1994 (above).

Witherby, H. F. et al. (1958) in: The Handbook of British Birds. Vol. IV. London: H. F. & G. Witherby Ltd. A short remark by H. F. Witherby quoted.

"Dr C. B. Ticehurst mentioned two large birds taken in Fair Is. on Sept. 23, 1905, which he considered to be C. a. sakhalina. I have examied these: female wing 116, bill 40, male wing 119, bill 35. The bills are certainly very large, but the wing of the female is short for sakhalina, and in both birds there is only slight edging of white on the outer webs of the inner primaries instead of the white extending to the rhachis as is usual in sakhalina. Among other large British-taken birds, I have examined only three with a considerable amount of white on the outer webs of the inner primaries (...) In the last the white just reaches the rhachis and in the other two not quite. These may be referable to C. a. sakhalina, but before admitting that race to the list I think we should have more definite evidence, as very occasionally examples of C. a. alpina have an unusual amount of white on inner primaries."

CP: This is history, passed by recent genetical research. I just want the quotation here as a morphological reference.

Wymenga, E., Engelmoor, M., Smit, C. J. & T. M. Van Spanje (1990): Geographical breeding origin and migration of waders wintering in West Africa. Ardea 78: 83 - 112.

This paper discusses the geographical breeding origin and migration routes of 3.5 million waders using the Banc d'Arguin, Mauritania and Guinea-Bissau, based upon morphometrical data and supplementary ringing recoveries. For several species our analyses confirm earlier findings on breeding areas and migration routes. For at least part of the Ringed and Grey Plovers, Redshanks, and to a lesser extent also Bar-tailed Godwits, Whimbrels, Curlews and Turnstones, there are indications that birds wintering in Guinea-Bissau originate from breeding areas further north and east, as compared to birds wintering in Mauritania. The morphological characteristics and measurements do not allow the determination of the exact location of the breeding areas. This is due to clinal gradients in measurements, as a result of which there is much overlap in sizes. During spring migration most wader species wintering in W. African coastal wetlands travel via a route following the W. African and W. European coastline. Little Stint, Curlew Sandpiper and Curlew are exceptions to this rule. There are indications that at least part of these birds migrate through NW Africa, the Mediterranean and the Black Sea area.

Zajac, R. (1980): Different autumn migration rates of sexes in the Dunlin Calidris a. alpina, as determined by means of normal probability paper. Acta orn. 17: 107 - 118.

Zwarts, L., B. J. Ens, M. Kersten & T. Piersma (1990): Moult, mass and flight range of waders ready to take off for long-distance migrations. Ardea 78: 339 - 364.

Wader species wintering on the Banc d'Arguin increased their body mass by about 40 % during the 4 - 6 weeks before their departure in spring. This estimate is based on 1) the empirical fact that most waders which had finished or suspended their body moult into summer plumage were heavy and thus ready to take off, and 2) the assumption that only the heaviest birds in the population left, which allowed the mass of disappearing waders to be estimated from counts and the frequency distribution of body masses in samples of captured birds. The mass gain on the Banc d'Arguin is just over 1 % per day, when expressed as a proportion of winter mass. A review of studies on waders preparing for migration shows that 1) the total migratory reserve adds 20-80 % to winter mass, 2) the rate of mass gain is 0.1-4 % per day and 3) the period of mass increase lasts four weeks on average, but longer if waders prepare for spring migration on the wintering areas. We suggest that all wader species leaving the Banc d'Arguin at the end of April and the beginning of May are able to reach SE and NW Europe without refuelling. This seems only possible if current equations to predict flight range systematically underestimate this range, even when the energetic benefits of favourable winds at high altitude are taken into account.

  • To "Studies of migrating Dunlin Calidris alpina in the Sound area, S. Sweden: Introduction"
  • To "Phenology and biometry of Dunlin Calidris alpina migrating by way of the Sound area, S. Sweden"
  • To "Migrating Dunlin Calidris alpina in the Baltic area: the moult issue"
  • To "Wintering and spring staging Dunlin Calidris alpina in the south Baltic area"
  • To "Migratory progress of juvenile and adult Dunlin Calidris alpina from two perspectives: the Baltic and the Waddensea"
  • To "Bill-length distributions in Dunlin Calidris alpina"
  • To the bill length account
  • About "adult buff" coverts
  • To the Meissner scale
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    Last addition (133 entries) 6.2.06, links changed 1.6.04.