Papers relevant to the study of Dunlins:
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).
Andersson R. C., Wong P. L. & C. M. Bartlett (1994): Skrjabinoclava aculeata (Acuarioidea: Acuariidae) in Dunlins (Calidris alpina) from both Iceland and Louisiana, U.S.A. J. Helm. Soc. Wash. 61: 129 - 132.
CP: Skrjabinoclava is a nematode, living in the guts of birds. Nematodes affect most species, e. g. Cormorant: Contracaecum rudolphii and Great Tit (3 nematode species found in Poland). Both poultry and cage birds like parrots may be infected as well. In Copeia, Vol. 1997: 875 - 880, Neil J. L. Heideman states: "Reptile nematodes affect their hosts in a variety of ways. These include the lowering of body condition, a reduction in fat deposition, a reduction in fecundity, and a lowering of locomotor capability, to name but a few."
Andrews, D. J. (1992): The diet of wintering Short-eared Owls on Strangford Lough. Irish Birds 4: 549 - 554.
Ash, J. S. & J. E. Mishell (1981): The Dunlin Calidris alpina in Ethiopia and Somalia. Scopus 5: 32 - 33.
Austin, G. & M. M. Rehfisch (2005): Shifting non-breeding distributions of migratory fauna in relation to climatic change. Global Change Biology, 11, 31-38.
Avery, M. I. & R. H. Haines-Young (1990): Population estimates for the Dunlin Calidris alpina derived from remotely sensed satellite imagery of the Northern Scotland. Nature 344: 212 -215.
Baccetti, N, Serra, L., Magnani, A. & G. Cherubini (1999): Timing of attachment to wintering site as revealed by experimental displacement of Dunlins (Calidris alpina). J. Orn. 140: 309 - 317.
Two groups of adult and two groups of juvenile colour-marked Dunlins (Calidris alpina) were moved from the wintering site in four successive years, in order to assess the existence of time- and age-dependent differences in homing behaviour and, in particular, to determine when attachment to wintering grounds is achieved by juveniles. Each group was released on different dates at the beginning of the wintering season 133 km to the south of the capture site. We expected that the behaviour of adults would not vary according to date, whereas that of juveniles would. In all four experiments the majority of birds left the release site. Juveniles displaced early in the season (5 Nov.) remained at the release site in higher numbers (34 % vs 0 - 14 %) and homed to a lesser extent (20 % vs 57 - 62 %) than juveniles displaced late in the season (13 Dec.) and both adult groups. The final return rates of adults displaced early and late in the season (8 and 24 Nov.) were similar. Most birds that left the release site departed within 20 days of displacement, whereas observations of colour-marked Dunlins at the capture site indicated a more gradual pattern of return. The first homed birds were observed three days after release, but new birds continued arriving back at the release site for at least 40 days longer. Most juvenile Dunlins seem to become attached to a wintering site during November. Recovery rates of displaced and non-displaced birds retrapped in following winters suggested that year-to-year site fidelity is developed after a longer period.
Baker, M. C. (1982): Individuality of Vocalizations in Dunlin: a Possible Acoustic Basis for Recognition of Parent by Offspring. The Auk 99: 771 - 774. Internet version of this paper.
Barbosa, A. (1996): Foraging habitat use in a Mediterranean estuary by dunlin, Calidris alpina. J. Coast. Res. 12: 996 - 999.
Barbosa, A. (1997): The effects of predation risk on scanning and flocking behavior in Dunlin. J. Field Orn. 68: 607 - 612. Internetversion av denna uppsats
Dunlin (Calidris alpina) scanning and flocking behavior was studied in two habitats with different predation risk. Mean flock size, time spent scanning, and mean scan duration were higher in rice fields (the less profitable and high-risk habitat) than in littoral habitats (the more profitable and low-risk habitat), although vigilance rate was not different between habitats. Increased scanning and flocking behavior probably increase efficency in predator avoidance. The results are explained as behavioral changes to ensure safety in a high predation-risk situation when starvation risk is also present.
Barter, M., Tomkinson, D., Sixian, T., Xiao, Y. & Q. Fawen (1997): Wader numbers on Chongming Dao, Yangtze Estuary, China, during early 1996 northward migration and the conservation implications. The Stilt 30: 7 - 13. Internet version of this paper.
Two comprehensive counts of waders on east Chongming Dao were carried out at the end of March and in mid April 1996. Total numbers counted declined from 24,770 to 10,950 between the two periods. The most common species (Dunlin, Kentish Plover and Great Knot) represented 90%, or more, of the total number on both counts, although the proportion of Dunlin doubled between the counts and those of Kentish Plover and Great Knot halved. The conservation significance of the Yangtze Estuary for waders is discussed.
Barter, M. & D. Tomkinson (1997): Wader departures from Chongming Dao (near Shanghai, China) during March/April 1996. The Stilt 31: 12 - 17. Internet version of this paper.
Waders departing from east Chongming Dao, a large island in the Yangtze estuary north of Shanghai, behave in a similar manner to that observed for departing waders elsewhere with respect to vocalisations, recruitment flights, flock size, composition and shape, and diurnal timing. Departure directions indicate that flocks are leaving for the Yellow River delta, or beyond, the Korean Peninsular or Japan.
Bengtsson, S.-A. & B. Svensson (1968): Feeding habits of Calidris alpina L. and C. minuta Leisl. (Aves) in relation to the distribution of marin shore invertebrates. Oikos 19: 152 - 157.
Blew, J., K. Günther & P. Südbeck (2005): Bestandsentwicklung der im deutschen Wattenmeer rastenden Wat- und Wasservögel von 1987/1988 bis 2001/2002. Vogelwelt 126: 99 - 125.
The German Wadden Sea at the North Sea coast of Lower-Saxony and Schleswig-Holstein is a staging area for more than 4 Million migratory waterbirds of the East-Atlantic Flyway; many of those breed in the Arctic and / or overwinter as far South as tropical Africa. Since 1980 most German Wadden Sea sites have been counted at least two times per year during internationally synchronous counts (January and in another month of the year), many of them monthly and – since 1987 – many others in selected spring-tide counting areas every 14–15 days throughout the year. For the first time the migratory bird counts of the German Wadden Sea have been compiled into one database to calculate numbers and trends of 34 species. Among the 34 species considered here for the period 1987–2002, four show a positive trend, 14 show a negative trend, and of 16 species numbers fluctuate too much to calculate a statistically significant trend. Three of the increasing species (Great Cormorant, Spoonbill, Barnacle Goose) show general
population increases and/or benefit from improved food availability or habitat changes in the
Wadden Sea. For the Shelduck, measures to protect the moulting individuals off the coast of
southern Schleswig-Holstein might have contributed to their slight increase. Three (Brent Goose,
Wigeon, Mallard) of the 14 decreasing species seem to show general population decreases, due
to factors like breeding failure in the Arctic or increased mortality due to cold spells in some
winters in the Wadden Sea. Four species (Common Eider, Oystercatcher, Red Knot, Herring
Gull) are to varying degrees dependent on bivalves; here, factors like climate change, lack of
cold winters and mussel fishery may either solely or in combination cause the decreasing trends.
Seven wader species (Avocet, Golden and Grey Plover, Red Knot, Dunlin, Bar-tailed Godwit,
Redshank), however, are birds which breed in the arctic, migrate south to tropical Africa and
occur in the Wadden Sea in high numbers – thus are largely dependent on the Wadden Sea as
their indispensable food source for fast replenishing during their migration. For these species the causes are yet unknown, but may relate to negative effects of food availability/benthos organisms in the Wadden Sea. The monitoring program proved to be successful to describe numbers and trends of waterbirds in the Wadden Sea, using an agreed method to count, compile and analyse
the data. This way it fulfills the obligations of international directives and provides the basis
to further analyse the causes of population trends and to formulate and implement adequate
Blomqvist, D. & O. C. Johansson (1991): Distribution, reproductive success, and population trend in Dunlin Calidris alpina schinzii on the Swedish west coast. Ornis Svecica 1: 39 - 46.
Blomqvist, D., Johansson, O. C., Unger, U., Larsson, M. & L.-Å. Flodin (1997): Male aerial display and reversed sexual size dimorphism in the dunlin. J. An. Behav. 54: 1291 - 1299.
Reversed sexual size dimorphism, with males smaller than females, is common in waders. The aerial display hypothesis suggests that sexual selection in males favours aerial agility, and hence small size, in species with male display flights. We tested this hypothesis in the dunlin,Calidris alpinaDisplay flights were uncommon in the early breeding season but increased markedly when females began laying. Male display areas were largely overlapping, and display flight seemed to be mainly an advertising signal to potential mates. Display rate, as well as proportion of time spent in aerial display, increased with decreasing male size. During aerial display, small males also performed costly hovering flights more often and for relatively longer than large males. These results support the aerial display hypothesis.
Blomqvist, D. & A. Pauliny (2007): Inavel och förlust av genetisk variation hos sydlig kärrsnäppa (Calidris alpina schinzii) på svenska Västkusten. Länsstyrelsen, Hallands län. Here the web version of this report.
Blomqvist, D. & M. Larsson (2007): Miljögifter i ägg av sydlig kärrsnäppa (Calidris alpina schinzii) från Båtafjorden, Halland. Länsstyrelsen, Hallands län. Here the web version of this report.
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.
Boros, E., Andrikovics, S., Kiss, B. & L. Forró (2006): Feeding ecology of migrating waders (Charadrii) at sodic-alkaline pans in the Carpathian Basin. Bird Study 53: 89 - 91. Link to Internet version of this paper (It still has to be bought).
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.
Browning, M. R. (1977): Geographic variation in Dunlins calidris alpina of North America. Canadian Field Naturalist 91: 391 - 393.
Browning, M. R. (1991): Taxonomic comments on the Dunlin Calidris alpina from northern Alaska and eastern Siberia. Bull. Br. Orn. Club 111: 140 - 145.
Buchanan, J. B., Schick, C. T., Finger, M. A., Johnson, T. M. & S. G. Herman (1988): Dunlin weight changes in relation to food habits and available prey. J. Field Orn. 100: 265 - 272. Internetversion of this paper.
The total and fat free weights of Dunlins at 3 estuaries in western Washington state decreased significantly between early and late winter (December-March). Total and fat free weights of a fourth winter population increased during the same study period. Total lipid weights of Dunlins decreased significantly during the same winter at all sites. In an analysis of food habits and prey availability, we found that the Dunlin population with the overwinter weight increase consumed the highest percentage of polychaetes and was the only one of the 4 populations
studied that selected polychaete worms in proportion to their availability.
Buchanan, J. B., Schick, C. T., Brennan, L. A. & S. G. Herman (1988): Merlin predation on wintering dunlins: hunting success and dunlin escape tactics. Wilson Bull. 100: 108 - 118. Internetversion of this paper
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.
Buehler, D. M. & A. J. Baker (2005): Population divergence times and historical demography in Red Knots and Dunlins. The Condor 107: 497 - 513.
We employed Bayesian coalescent modeling of samples of mitochondrial control region sequences in two species of shorebird, Red Knots (Calidris canutus) and Dunlins (Calidris alpina) to estimate evolutionary effective population size, population divergence times, and time to most recent common ancestor of genes in the samples. The gene trees for the two species contrast sharply: knot haplotypes were connected in a shallow, star phylogeny whereas Dunlin haplotypes were related in a deeper bifurcating genealogy. Divergence times of populations representing all six subspecies of knots are estimated to have occurred within the last 20000 (95% CI: 5600-58000) years, and evolutionary effective population sizes of females are small (Nef = 2000-14000). We hypothesized that breeding knots were restricted to unglaciated regions of Eurasia during the last glacial maximum, and gradually expanded eastwards into Alaska, the high Canadian Arctic and Greenland as the ice melted. Population divergence times in Dunlins are much older (58000-194000 ybp) and effective population size has historically been higher in major lineages (Nef = 12000-44000). We conclude that Dunlin populations were not severely reduced in size in the last 200000 years, and major lineages have differentiated under restricted gene flow for a much longer time than knots. Knots present a snapshot of genetic evolution in the last 20000 years, whereas Dunlins display patterns of genetic evolution over an order of magnitude longer time frame.
Byrkjedal, I. & J. A. Kalas (1983): Plover's Page turns into Plover's Parasite: a look at the Dunlin/Golden Plover association. Orn. Fenn. 60: 10 - 15.
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.
Choi, C., Gan, X. J., Ma, Q., Zhang, K. J., Chen, J. K.. & Ma, Z. J. (2009): Body condition and fuel deposition patterns of calidrid sandpipers during migratory stopover. Ardea 97: 61 - 70.
We compared seasonal variations in body condition and fuel deposition patterns
of five calidrid sandpipers at Chongming Dongtan (eastern China), a stopover site in the East Asian–Australasian Flyway. We tested the hypothesis that long-distance migrants show different body condition and fuel deposition patterns relative to those undertaking short-distance flights. Results indicated that the body condition and fuel deposition patterns of the sandpipers varied between the northward and southward migration seasons and between ageclasses. Great Knots Calidris tenuirostris and Red Knots Calidris canutus migrate southwards on a long-distance nonstop flight from Chongming Dongtan to northwest Australia, while covering on the return flight a relatively short-distance between Chongming Dongtan and the north Yellow Sea region. Both species attained a significantly higher body condition at Chongming Dongtan during the southward than northward migration. Moreover, they showed a significant increase in body condition at Chongming Dongtan during northward migration stopover, which we see as a recovery from the long flight from Australia. In contrast, Red-necked Stints Calidris ruficollis and Long-toed Stints Calidris subminuta, employing series of relatively short-distance flights during migration, indicated no significant difference in departure body condition at Chongming Dongtan between seasons, nor significant increase in body condition during either migration stopover. Dunlins Calidris alpina on the other hand, showed a significantly higher body condition during northward than southward migration stopover, most likely in anticipation of the longer travelling distance after leaving Chongming Dongtan during northward migration. This study confirms that the body condition and fuel deposition patterns among shorebird species that undertake long-distance nonstop flights are different from those that undertake series of short-distance flights, suggesting that the comparison of body condition and fuel deposition patterns of calidrid sandpipers can be an important tool to understand their migration strategies.
Clark, J. A., Robinson, R. A., Clark, N. A. & P. W. Atkinson (2004): Using the proportion of juvenile waders in catches to measure recruitment. WSG Bull. 104: 51 - 55. Internet version of this paper.
As it is difficult to collect data on the success of breeding in the high arctic, the proportion of juvenile waders in catches outside the breeding season has been used to provide a measure of recruitment. This paper considers different ways of assessing the proportion of juveniles among waders in the non-breeding season and recommends the use of an individual-based index using a generalised linear model.
Clark, N. A. (1983): The ecology of Dunlin (Calidris alpina L.) wintering on the Severn Estuary. PhD thesis, University of Edinburgh.
Clark, N. (1984): Ageing criteria for Dunlins. WSGB 42:39.
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.
Colwell, M. A. & R. J. Cooper (1993): Estimates of coastal shorebird abundance: the importance of multiple counts. J. Field. Orn 64: 293 - 301. Internet version of this paper.
Variability in estimates of shorebird abundance derived from four sequential 30-min counts conducted at Humboldt Bay, California during November 1990 and February 1991 was estimated. The November survey was scheduled so that the first of four consecutive
30-min counts occurred when the tide had just inundated intertidal habitats, whereas inundation
occurred during or just after the last of four February counts. Percent bias was
normally high (15-78%) in both counts when compared with the maximum count of selected
shorebird species or groups. Compared with November counts, those in February varied
less and peaked during the penultimate and last count. These findings suggest hat multiple
countsa re more useful than single surveys, especially to identify optimal observation times
relative to inundation of intertidal flats. Data from multiple surveys offer at least two
potential ways of estimating shorebird abundance: average (or median) estimates and single,
Conklin, J. R. & M. A. Colwell (2007): Diurnal and nocturnal roost site fidelity of Dunlin (Calidris alpina) at Humboldt Bay, California. The Auk 124: 677 - 689. Internet version of this paper.
Shorebird roosts are often considered traditional, on the basis of predictable occupancy by large numbers of birds over long periods. However, fidelity of individuals to roosts at fine spatial and temporal scales, particularly at night, has rarely been described. We compared diurnal and nocturnal use of high-tide roosts by radiotagged Dunlin (Calidris alpina pacifica) wintering (November-March) at Humboldt Bay, California. Despite high fidelity to the study area, fidelity to particular roosts was relatively low and highly variable. At night, Dunlin used fewer roosts, were more faithful to primary roosts, and moved shorter distances between successive roosts than during the day. Day and night roosts differed in location, habitat, and distance from tidal flats. At night, Dunlin made greater use of pasture, and less use of islands and manmade structures. Day and night strategies of high-tide space use by Dunlin may be related to differences in food availability or predation danger. Our results illustrate that notions of tradition and site fidelity are scale-dependent and that knowledge of space use across the full range of environmental conditions is necessary for appropriate management of shorebird habitat.
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. (1984a): 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. (1984b): 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.
Dekker, D. & R. Ydenberg (2004): Raptor predation on wintering Dunlins in relation to the tidal cycle. Condor 106: 415 - 419.
Desholm, M. (1998:) Length of stay and volume of autumn staging Dunlins Calidris alpina at the Tipperne reserve, Denmark. Ornis Svecica 8: 1 - 10.
Desholm, M., Wegeberg, M. & K. N. Mouritsen(1999): Vigilance and flocking behaviour of tactilely foraging Dunlins Calidris alpina. Avocetta 23: 42-47.
Field observations of the relationship between vigilance, foraging, and flocking behaviour in Dunlins Calidris alpina were carried out under optimal field conditions. The results show that central Dunlins within larger flocks devote less time to vigilant behaviour and more time to feeding (higher probing rate) than more peripheral conspecifics. The most coherent explanation for the difference in vigilance level between peripherally and centrally foraging Dunlins is the individual birds´ perception of a higher predation risk when exposed. It is argued that vigilance for predators in Dunlins constrains foraging activity rather than vice versa. Hence, the adaptive significance of flocking in Dunlins may be an increased feeding activity without jeopardising predator surveillance.
Dick, W. J. A. & M. W. Pienkowski (1979): Autumn and Early Winter Weights of Waders in North-West Africa. Orn. Scand. 10: 117 - 123. Internet link to this paper
The weights of waders in autumn, soon after their arrival in north-west Africa, and the subsequent changes in weight until early winter are compared with patterns known from Europe and elsewhere. Throughout the period, for most species weights, and probably levels of fat and protein, were considerably lower in north-west Africa than in Britain. Many birds arrived with extremely low weights; some, extremely emaciated, were found dead or dying. Waders with similar reductions in weight have been found dead in cold weather in temperate and arctic areas. Some weight increases probably due to fat deposition occurred in onward migrants. Apart from these, no increases in weights were observed for waders in north-west Africa in late autumn and winter, unlike those wintering in north-west Europe. In all species weights remained much lower than those of the same species wintering in Britain, where fat reserves cause mid-winter peaks in weight. It is argued that where adverse weather conditions are infrequent, and therefore the need for fat and protein reserves unlikely, there are advantages in keeping weight low by minimizing such reserves.
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 and most other workers.
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 Baltic Sea, 1. Habitat use and food selection. J. Sea Res. 42: 49 - 64.
The feeding habits of migrating dunlins Calidris alpina staging in different non-tidal coastal habitats in the southern Baltic Sea are described. The study also focuses on the structure of the benthic macrofauna of these habitats and the diet choice of dunlins. All investigations were carried out on Langenwerder Island (Wismar Bay), where different types of flats and beaches harbour a total of 30 to 40 species of marine macrofauna. The composition of the macrobenthos differed considerably between the eulittoral sandbank, the eulittoral mudflat, the pebble beach, and the sublittoral surroundings. Most dunlins were observed foraging in flocks of up to several hundred individuals on the eulittoral flats. Densities of up to 20 to 30 foraging dunlins ha-1 occurred annually during peak migration in September and October. Macrobenthos biomass in these habitats fluctuated between 20 and 40 g AFDM m-2. The mean total food consumption of dunlins during autumn migration was estimated at 0.01 g AFDM m-2 d-1. The predation pressure could be estimated at 3 to 6% of the suitable food supply. Dunlins staging on Langenwerder were able to attain a pre-migratory mass gain of 0.2 to 0.5% of their body weight per day within an 8 to 12-h daily feeding period. The birds fed predominantly on the polychaete Hediste diversicolor by probing. They selected small 7 to 31-mm-long individuals. When water levels were high, and the eulittoral flats inundated, many dunlins switched to foraging along the shorelines where a variety of small prey were taken from spilled macrophytes. Dunlins sometimes obviously ignored their most important food H. diversicolor, although available, by feeding on other prey such as juvenile fishes and shrimps, dipteran larvae or spilled amphipods. When feeding on amphipods, dunlins selected the smallest individuals.
Dierschke, V., Kube, J. & H. Rippe (1999): Feeding ecology of
dunlins Calidris alpina staging in the southern Baltic 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 seasonal variability 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 stock 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.
Dodd, S. (2000): Weight loss in Dunlin Calidris alpina over the high tide period. WSGB 91: 28 - 29.
DOF. Fugle på Sjaelland. (1986 - 1993): (Annual Report from Sealand)
Domínguez, J. (2006): Invernada y Migracion de Limicolas en el Litoral Atlantico Iberico, Ministerio de Medio Ambiente. (Fieldwork 1978-82 and 1989-93 (Spain) and 1987-91 (Portugal). Everything needed to evaluate the numbers of shorebirds wintering on the Atlantic coasts of Spain and Portugal is here.) Available on the Internet.
To date, 55 species of wader have been recorded from the Atlantic coast of Iberia. Of these, 35 are regularly present. A review of census data suggests that about 105,00 waders overwinter in Spain, and about 106,000-123,000 in Portugal. The most numerous overwintering species are (in decreasing order) the Dunlin, Blacktailed Godwit, Avocet, Grey Plover and Redshank; these five species account for about 78 % of the total overwintering wader population. Fourteen sites support wintering populations og >1000 individuals. On the basis of total overwintering wader populations, the estuario do Tejo and the ria de Faro (in Portugal) and the marismas del Guadalquivir and the Bahia de Cádiz (in Spain), are of international importance. On the basis of the 1 % criterion, 7 sites are of international importance for at least one species, of these, the most outstanding are the bahia de Cádiz (internationally important for 6 species), the estuario de Tejo (4 species), ria de Sado and ria de Faro (three species).
The available data for passage periods suggest that, for most species, the proportion of stopover in wetland sites in the northern Iberian Peninsula is moderate or low; stopover in wetland sites in Andalucia and southern Portugal is much more significant.
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.
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.
Ehlert, W. (1964) Zur Ökologie und Biologie der Ernährung einiger Limikolen-Arten. J. Orn. 105: 1 - 53.
(My translation; CP)
1. Based on mappings of flats, field observations and investigations of stomach and intestine contents as well as observations of caged birds this study investigates the food and feeding habits of wader species Calidris alpina, Calidris canutus and Crocethia alba in the tidal flats of the isle of Mellum.
2. The investigations of the tidal flats refers to Linke (1939) and O. Schuster (1951). Sediment samples showed, that the Mellum flats are built up mainly from fine sand and hence should be characterised as a sand flat. Only in the eastern parts (where the bivalve banks are situated) there was an admixture of up to 12 % of silt, so that the sand flat here turns into a clay flat.
3. The biocommunities of the south and east flats were qualitatively and quantitatively separated into two biocoenoses: the Arenicola-Cardium-association and the Pygospio-Corophium-association. Both associations were subdivided into different variants. Differences relative to Scuster's investigations were demonstrated and discussed. The biocoenoses of the bivalve banks, the bays to the west and the northern beach zone were also investigated; their endofaunic contents were lower than those of the southern flats.
4. The abundance and distribution of prey important to the waders were mapped.
5. Abundance of sandpiper species during the migration periods: Dunlins were most common and of most regular occurrence. On the contrary Knot occurence was highly irregular. Sanderlings occurred regularly, but in rather small numbers. Summering birds of all three species were rare at Mellum.
6. To the diurnal rhythm of the sandpipers: The daily shift of the flocks wa s mapped based on sketches from the diaries. It turned out that the birds insert a longer resting pause by noon and in the afternoon hours than at other parts of the day. These observations were conformed by volumetric analysis of stomach contents. Contrary to Dunlin and Sanderling Knots were observed foraging close to the island only on rare occasions. Rainstorms and abnormal tides had a considerable influence on the diurnal rhythm of sandpipers.
7. 151 stomach analyses of Dunlins showed, that these birds are pronounced Nereid eaters at Mellum: 96.7 % of the investigated animals had eaten these polychaetes, which could be established from the presence of Nereid mandibles. Molluscs - in particular Hydrobia - were the second commonest prey. Comparison with the literature shows, that the Dunlins eating Nereids at Mellum are no local exception. On the other hand insects and their larvae are the preferred prey on breeding-grounds. (...)
Elner, R.W. et al. (2005): Evidence of a new feeding mode in western sandpiper (Calidris mauri) and dunlin (Calidris alpina) based on bill and tongue morphology and ultrastructure. Marine Biology 146: 1223 - 1234.
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.
Engelmoor, M. (2008): Breeding origins of wader populations utilizing the Dutch Wadden Sea as deduced from body dimensions, body mass, and primary moult. Thesis, Un. of Groningen. Internet version of the thesis
Etheridge, B. & W. G. Taylor (1982) Biometrics of breeding Dunlins Calidris alpina from South Uist. WSGB 36: 2 - 3.
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. & W. G. Hale (eds.) (1984): Coastal waders and wildfowl in winter. Cambridge: Cambridge University Press.
Evans Ogden, L. J., Hobson, K. A., Lank, D. B. & S. Bittman (2005): Stable isotope analysis reveals that agricultural habitat provides an important dietary component for nonbreeding Dunlin. Avian Conservation and Ecology - Écologie et conservation des oiseaux 1(1): 3. Internet version
Although shorebirds spending the winter in temperate areas frequently use estuarine and supratidal (upland) feeding habitats, the relative contribution of each habitat to individual diets has not been directly quantified. We quantified the proportional use that Calidris alpina pacifica (Dunlin) made of estuarine vs. terrestrial farmland resources on the Fraser River Delta, British Columbia, using stable isotope analysis (?13C, ?15N) of blood from 268 Dunlin over four winters, 1997 through 2000. We tested for individual, age, sex, morphological, seasonal, and weather-related differences in dietary sources. Based on single- (?13C) and dual-isotope mixing models, the agricultural habitat contributed approximately 38% of Dunlin diet averaged over four winters, with the balance from intertidal flats. However, there was a wide variation among individuals in the extent of agricultural feeding, ranging from about 1% to 95% of diet. Younger birds had a significantly higher terrestrial contribution to diet (43%) than did adults (35%). We estimated that 6% of adults and 13% of juveniles were obtaining at least 75% of their diet from terrestrial sources. The isotope data provided no evidence for sex or overall body size effects on the proportion of diet that is terrestrial in origin. The use of agricultural habitat by Dunlin peaked in early January. Adult Dunlin obtained a greater proportion of their diet terrestrially during periods of lower temperatures and high precipitation, whereas no such relationship existed for juveniles. Seasonal variation in the use of agricultural habitat suggests that it is used more during energetically stressful periods. The terrestrial farmland zone appears to be consistently important as a habitat for juveniles, but for adults it may provide an alternative feeding site used as a buffer against starvation during periods of extreme weather. Loss or reduction of agricultural habitat adjacent to estuaries may negatively impact shorebird fitness, with juveniles disproportionately affected.
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
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.
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.
Gerasimov, Y. N. & N. N. Gerasimov (2001): Records of northward migration of Dunlin Calidris alpina through Kamchatka, Russia. Stilt 39: 37 - 40.
Gilg, O., Sané, R., Solovieva, D. V., Pozdnyakov, V. I., Sabard, B., Dimitri, T., Zöckler, C., Lappo, E. G. Syroechkovski, E. E. & G. Eichhorn (2000): Birds and Mammals of the Lena Delta Nature Reserve, Siberia. Arctic 53: 118 - 133. Pdf version on the web.
The Lena Delta is the largest arctic delta covered entirely by tundra. Protected since 1986, it is one of the richest areas in the Arctic north of 71° N for both species diversity and breeding densities. Between 6 June and 17 August 1997, 16 mammal
species and 76 bird species were recorded in the Lena Delta Nature Reserve and the surrounding buffer zone. Several species are new to the region: far-eastern curlew, fieldfare, redwing, arctic warbler, red-breasted flycatcher, and common rat. New breeders are merlin and arctic warbler. These 1997 records, combined with those from earlier studies, give a total of 122 bird species for the region. Of these, 67 have been found breeding at least once. Densities ranging from 245 to 641 birds per km2 were recorded in two restricted study areas. Such densities are unusually high north of 70° N for non-colonial breeding birds. Lapland longspur (100–300 individuals/km2), red phalarope (up to 200 ind./km2), and several Calidris species were the most common. Ruddy turnstone and dunlin had densities higher than those previously reported from the Lena Delta and other Siberian sites. Among the shorebirds, spotted redshank, pintail snipe, grey plover, dunlin, and curlew sandpiper may have extended their breeding range or
increased in population during the last 15 years. But further evidence is still needed to confirm the westward extension of spectacled eider, long-billed dowitcher, and sharp-tailed sandpiper.
Gill , R. E., Jr., & C. M. Handel (1990): The importance of subarctic intertidal habitats to shorebirds: a study of the central Yukon-Kuskokwim Delta, Alaska. Condor 92: 709-725. Pdf version on the web.
A 6-year study of shorebird use of intertidal habitats of the Yukon-Kuskokwim Delta revealed this area to be one of the premiere sites for shorebirds throughout the Holarctic and worthy of designation as a Hemispheric Shorebird Reserve in the Western Hemisphere Shorebird Reserve Network. The study area, which covered 10% (300 km2) of the delta's intertidal flats, regularly hosted 17 species of shorebirds between late April and mid-October. The greatest use was during the postbreeding period (late June-October), when Dunlins (Calidris alpina), Western Sandpipers (C. mauri), and Rock Sandpipers (C. ptilocnemis), each with large local nesting populations, accounted for 95% of the shorebirds recorded. Peak counts during autumn approached 300,000 birds. Considering the seasonal occurrence and turnover of populations, we estimate l-2 million shorebirds use the central delta each year. The delta supports large fractions of the Pacific Rim or world populations of Bar-tailed Godwits (Limosa lapponica), Black Turnstones (Arenaria melanocephala), Red Knots (C. cartutus), Western Sandpipers, Dunlins, and Rock Sandpipers. Densities of shorebirds using the central delta's four major bays and connecting coastal areas peaked at 950 shorebirds/ km2 in early September. Hazen Bay frequently hosted more than 1,200 shorebirds/km2. Postbreeding shorebirds used intertidal habitats in three distinct patterns according to age class. For most species (n = 7), there was a period when adults appeared first, followed by a brief interval when adults and juveniles mixed, then by a prolonged period when only juveniles remained. In the second pattern (n = 3 species), adults moved onto the intertidal flats first, were later joined by juveniles for a prolonged staging period, then migrated with them. In the third pattern (n = 3 species), only juveniles used the delta's intertidal habitat. Temporal segregation among species and age groups may minimize competition for food and thereby allow the delta to support high diversity and numbers of shorebirds.
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.
Goss-Custard, J. D. & M. E. Moser (1988): Rates of change in the numbers of Dunlin, Calidris alpina, wintering in British estuaries in relation to the spread of Spartina anglica. J. Appl. Ecol. 25: 95 - 109.
(1) The number of dunlin, Calidris alpina alpina (L.), wintering in the British Isles has decreased by almost half since 1973-74, much of the decrease occurring before 1977-78. A similar decrease seems to have occurred in the other main wintering areas in Holland and France between 1973-74 and 1977-78. But since then, numbers in these two countries have not decreased whereas in Britain numbers declined by a further 77 000 by 1985-86.
(2) The rate of decline since 1977-78 has varied between British estuaries, many showing no change in numbers. Dunlin numbers declined at the greatest rates in estuaries where cord grass, Spartina anglica, has spread most over the intertidal flats where the birds feed. In estuaries where the extent of Spartina has not changed, numbers of dunlin have not declined significantly, except in some small estuaries in south Devon and in north Scotland.
(3) The results suggest that most birds displaced from estuaries where Spartina has spread have not yet been able to re-establish themselves elsewhere in Britain or in some other countries within the wintering range of Calidris alpina. Nor have dunlin numbers increased in estuaries where Spartina has declined through natural die-back. The reasons for this, and the implications of the results as a whole for the conservation of dunlin, are discussed.
Granadeiro, J. P., M. P. Dias, R. C. Martins & J. M. Palmeirim (2005): Variation in numbers and behaviour of waders during the tidal cycle: implications for the use of estuarine sediment flats. Acta Oecologica 29: 293 - 300.
Estuarine sediment flats are essential feeding areas for waders, but their exploitation is constrained by the movements of tides. In this cyclic environment the exposure period of sediment flats decreases several fold from upper to lower flats, and the moving tidal waterline briefly creates particular conditions for waders and their prey. This study attempts to determine how the exposure period and the movement of the tide line influence the use of space and food resources by waders across the sediment flats. Wader counts and observations of feeding behaviour were carried out in all phases of the tidal cycle, in plots forming a transect from upper to lower flats, thus representing a gradient of exposure periods. Pecking, prey intake, and success rates varied little along the gradient. Some species actively followed the tide line while foraging, whereas others are evenly spread over the exposed flats. Black-tailed Godwit, Dunlin and Avocet were 'tide followers', whereas Grey Plover, Redshank and Bar-tailed Godwit were 'non-followers'. Densities of 'followers' near the tide line were up to five times higher than elsewhere. Species differed markedly in the way they used space on the flats, but in general the rate of biomass acquisition (in grams of ash-free dry weight per time exposed) was much higher in lower flats. However, this preference was insufficient to counter the much longer exposure of the upper flats, so the total amount of biomass consumed on the latter was greater. Therefore, it was in these upper flats that waders fulfilled most of their energetic needs. Consequently, upper flats are of particular importance for the conservation of wader assemblages, but because they are usually closer to shore they tend to suffer the highest pressure from disturbance and land reclamation.
Greenwood, J. G. (1979) Post-mortem shrinkage of Dunlin Caldris alpina
skins. Bull. Br. Orn. Club 99: 143 - 145.
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).
Gromadzka, J. (1998): Numbers of juvenile Dunlins Calidris alpina ringed at the Vistula Mouth (southern Baltic, Poland) in relation to arctic breeding conditions. Int. Wader Stud. 10: 85 - 87. Internet version of this paper.
The breeding conditions for waders in those arctic areas from where Dunlins Calidris alpina migrate to the southern Baltic, expressed by two kinds of estimation over six years, are compared with changes in numbers of juvenile Dunlins ringed in the same years in one of the southern Baltic staging posts during autumn migration at the Vistula mouth. Changes in numbers of juveniles caught at the Vistula mouth from year to year seem to reflect natural fluctuations in the age
structure of Dunlin flocks migrating through the ringing area.
Günther, K. & H.-U. Rösner (2000): Bestandsentwicklung der im schleswig-holsteinischen Wattenmeer rastenden Wat- und Wasservögel von 1988 bis 1999. Vogelwelt 121: 293 - 299.
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 the distribution and migration ecology of waterbirds for the benefit of nature conservation in the Afro-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.
During the moult, birds sequentially replace their flight feathers and thus temporarily have gaps in their wings. These gaps will vary in size and position(s) during the course of the moult. We investigated the aerodynamic effects of having moult gaps in a rectangular wing by using a vortex-lattice (panel) approach, and we modelled the effect of moult gap size at the wing moult initiation position, of gap position in the primary tract and of two simultaneous gaps (as occurs during secondary feather moulting in many birds). Both gap size and gap position had a detrimental effect on aerodynamic performance as measured by lift curve slope, effective aspect ratio and the aerodynamic efficiency of the wing. The effect was largest when the moult gap was well inside the wing, because the circulation declines close to the wing tip. In fact, when the gap was at the wing tip, the performance was slightly increased because the lift distribution then became closer to the optimal elliptical distribution. The detrimental effect of moult gaps increased with increasing aspect ratio, which could help to explain why large birds have relatively slow rates of moult associated with small gaps.
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.
Hicklin, P. W. (1987): The migration of shorebirds in the Bay of Fundy. Wilson Bull. 99: 540 - 570.
Large populations of 34 species of shorebirds migrate in late summer and fall to the wide muddy intertidal areas of the upper Bay of Fundy in preparation for the transoceanic flight to South American wintering grounds. Southward migration through Fundy extends from 1 July to 11 November, although the main passage usually occurs between 20 July and 20 September. Shorebirds are most numerous during August. The average length of stay for the Semipalmated Sandpiper (Culidris pusilla) is 15 days. Estimates of total numbers for the migratory period of the nine most common species range between 800,000 and 1,400,OOO birds. The Semipalmated Sandpiper constitutes 95% of all shorebirds recorded. The populations of Semipalmated Sandpipers stopping in the Bay of Fundy during southward migration each year represent 42-74% of the world population of this species. The Black-bellied Plover (Pluvialis squatarola) is the only species that migrates via the Bay of Fundy in spring in numbers comparable to those recorded in late summer and fall.
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. Internet version of this paper
In breeding populations of C. alpina in northern Alaska (71 ° N), the prebasic molt of adults is condensed into 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. Internetversion av uppsatsen.
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). The Condor 73: 93-99. Internet version of this paper.
On the Yukon-Kuskokwim Delta in western Alaska, adult C. alpina arrive in mid-May, establish territories, pair, nest, and care for young before starting their prebasic molt. After the young fledge, the red-backs shift from inland marsh tundra to coastal habitats, at which time molt intensifies. Feather replacement is complete prior to arrival in late September and October on their north temperate wintering quarters. The result is that breeding and molt are fitted, in sequence, into the summer schedule of events and do not overlap. In the C. alpinu populations at Barrow, Alaska, 10" latitude farther north, breeding and molt overlap and molt proceeds at a faster rate. Such modifications are results of adaptive responses to the shorter summers at the higher latitudes and, to a lesser extent, to the more severe and unpredictable weather there. Results support the hypothesis that the timing of breeding season events in arctic shorebird populations is strongly affected by the length and character of the summer season.
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.
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.
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.
Hötker, H. (1995): Aktivitätsrhythmus von Brandgänsen (Tadorna tadorna) und Watvögeln (Charadrii) an der Nordseeküste. J. Orn. 136: 105 - 126.
Data yielded by scan observations in the Nordstrand Bay were used to construct time-activity budgets of Shelduck, Oystercatcher, Ringed Plover, Knot, Dunlin, Ruff, Bar-tailed Godwit, Curlew, Spotted Redshank, Redshank, and Greenshank. All species except Ringed Plover and Ruff showed a tidal rhythm of activities which included regular flights between hightide roosts and feeding sites. Night-time feeding activity was found to occur in Shelducks, Oystercatchers, Ringed Plovers, Grey Plovers, Dunlins, Curlews, and Redshanks, while Ruffs roosted at night. The data suggested that the activities of all species studied here (except the Ruff) followed the same patterns during day and night. After moonless nights, however, the feeding activity increased at daytime suggesting feeding was reduced during the darkest nights. Differences in the time-activity budgets of the species were related to body mass and size of food particles. The percentage of foraging was negatively correlated with body mass and size of food items. Small species spent more time flying than big species. The timing of movements of different wader species to and from their high tide roosts showed marked differences between the partly reclaimed Nordstrand Bay and more natural stopover and wintering sites like the Wash in England and the Hojer foreshore in Denmark. The time available for feeding on the mudflats was reduced in the Nordstrand Bay. Technical constructions for coastal protection thus influenced the activity rhythms of the waders.
Hötker, H. (2000): When do dunlins spend high tide in flight? Waterbirds 23: 482 - 485.
International Wader Study Group Bulletin Numbers 1-76 (1970-1995) and Volumes 77-105 (1995-2004) available at SORA, Searchable Ornithological Research Archive.
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.
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 , Aphriza , Tryngites , Philomachus  and Eurynorhynchus  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 moult 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 during 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.
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?
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 "Risk-prone or risk-averse? Dunlin Calidris alpina migrating with and without moult-gaps in the Baltic area"
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
To the Dunlin literature list K - Z
To wader literature list A - L
To the Dunlin literature list M - Z
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Last addition (121 entries) 14.8.09.