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).
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.
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
(The following part of the discussion
deserves to be quoted as well). Lilja (1969) found 20 % of the birds in
Finland in arrested moult; Lessels (1974) examined 17 adult Dunlins in
Northern Norway, 2 of which being in arrested and 9 in active wing
moult. This shows that at least part of the birds belonging to the
subspecies C. a. alpina (including C.
a. centralis, if accepted), starts
primary moult on or near their northern breeding grounds, or during the
first part of their migration to the Waddenzee or elsewhere in Western
Europe. Still I found arrested moult in only few specimens, and it is
virtually impossible to detect in any moulting wing whether it had
started from an arrested or non-arrested stay.
Boere, G. C. & C. J. Smit
(1981): Dunlin (Calidris alpina (L.)).
pp. 157 - 169 in: Smit, C. J & W. J. Wolff, Birds of the Wadden
Sea. Balkema, Rotterdam.
Brennan, L. A., Buchanan, J. B.,
Schick, C. T., Herman, S. G. & T. M. Johnson (1984):
Sex determination of Dunlins in winter plumage. J. Field Ornithol. 55:
343 - 348.
Discriminant function analysis was used to
create a statistical model that correctly predicted the sex of Dunlins
in 91.5 % of a sample of 200 bierds. Bill length had the greatest
discriminating power, followed by weight and wing length. Dunlins in
this study were slightly smaller than those reported from other studies
in western North America. We recommend researchers to test this model
with similar data from other Dunlin populations and, if necessary,
produce area specific sex determination models. Researchers wishing to
assign sexes to Dunlins banded for behavioral studies should do so only
if the posteríor probability of correct classification
exceeds a predetermined probability cutpoint. When discriminant
analysis is used to infer the sex ratio of a Dunlin population, the
entire sample should be used.
Brenning, U. (1987):
Der herbstliche Durchzug des Alpenstrandläufers im NSG
Langenwerder. Ber. Vogelw. Hiddensee 8: 4 - 19.
The passage of adult and juvenile birds
takes place in several waves being almost completed in the end of
October. During the years from 1976 to 1985 approx. 17 000 Dunlins were
caught. The average ratio between adult and juvenile birds was 1 : 5,
the measure of dispersion being from 1 : 1.3 to 1 : 10. Adult birds
stayed in average for 2.9 days and birds from the current year for 11.4
days. The average weight of adult Dunlins was 45.3 (34-67) g and that
of juvenile ones 46.1 (27-72) g. Juvenile birds showed a max. daily
increase in weight of 6.9 % of their body weight, in average of 1.5 -
0.7 % after a negative tendency during the first days. The problem of
the appearance of the subspecies C. a. sakhalina
could not yet be clarified definitely.
Brenning, U. (1989):
Der Zug des Alpenstrandläufers (Calidris alpina) auf der
Grundlage von Beringungen, Wiederfunden und Kontrollen in der DDR. Ber.
Vogelw. Hiddensee 9: 16 - 38.
About 28.500 Dunlins were trapped and
ringed in the GDR from 1964 to 1987, most of them at the coastal site
on Langenwerder. This contribution analyses 763 reported recoveries
(541 birds with Hiddensee rings and 222 ringed abroad) and draws
conclusions concerning the destinations of the Dunlin populations
migrating through the GDR. While only a small proportion of the
juvenile birds migrating in July and August spends the winter in
Europe, the Channel coast of France and the European Atlantic coast are
the most important wintering regions for the majority of juveniles.
Most adult Dunlins rest in the tidal marshes of the North Sea and the
Wash (east British coast) during the autumn moult, but in winter many
of them migrate to the west and south coasts of the British Isles. Some
of them winter on the West European coast, and a few in the
Mediterranean. Juveniles that reach Great Britain via Norway during
their first migration later migrate across the Baltic Sea to their
Buchanan, J. B., Schick, C. T.,
Brennan, L. A. et al. (1988): Merlin predation on
wintering dunlins: hunting success and dunlin escape tactics. Wilson
Bull. 100: 108-118.
Interactions between Merlins (Falco
columbarius) and Dunlins (Calidris alpina)
were studied at estuarine areas in western Washington during winter,
1979 to 1985. Twenty-five of 111 hunting flights by Merlins were
successful (22.5 %). Five of seven capture attempt techniques were used
successfully with a success rate of 4.9 %. The most common capture
techniques were the stoop at a flock and the chase of an individual
isolated from the flock. Most hunting flights (54 %) lasted less than 1
min, but hunts of over 5 min were observed (10 %). Hunting success
varied little with the duration of the hunting flight or the size of
the Dunlin flock initially targeted. Success rates for hunting flights
by Merlins were much higher in Washington (22.5 %) than reported from
California (12.5 %); these higher rates may be the result of a
functional response by Merlins in Washington. Dunlins exhibited three
distinct types of synchronized predator evasion flights. Dunlin
isolated from flocks were often pursued and captured. The most common
evasive measure used by isolated birds was a lateral dodge executed
while in linear flight away from the flock.
Chao, A., S.-H. Chang &
Y. H. Tsung (1991): Sexing Dunlins of Kung-Du area
by a statistical method. Journal of Chinese Association, 29: 131-143.
Clutton-Brock, T. H.
(1986): Sex ratio variations in birds. Ibis 128: 317 - 329.
Significant variation in the sex ratio at
hatching is unusual in birds. In contrast, sex differences in juvenile
mortality have been found in a variety of species, especially when food
is scarce. In some cases, these differences may be a consequence of
reduced viability of males when food is scarce but, in others, the
available evidence suggests that parental manipulation is involved.
Cramp, S. & K. E. L.
Simmons (eds.) (1983): The Birds of the Western
Palearctic. Vol 3. Oxford: Oxford University Press.
Cresswell, W. & D. P.
Whitfield (1994): The effects of raptor predation
on wintering wader populations at the Tyninghame estuary, southeast
Scotland. Ibis 136: 223 - 232.
Raptor predation on waders was studied by
direct observation of raptors hunting a known wader population and
subsequent recovery of dead waders. In each of three winters, raptor
predation was shown to be the most significant cause of mortality in
most small wader species. Sparrowhawks Accipiter nisus,
Merlins Falco columbarius and Peregrines F.
peregrinus attacked waders with a success rate of 11.6 %,
8.8 % and 6.8 %, respectively. Most waders attacked or found dead were
Redshanks Tringa totanus and Dunlin Calidris
alpina; most were killed by Sparrowhawks. Kleptoparasitism of raptors carrying prey by
Carrion Crows Corvus corone significantly
increased the winter mortality of some waders. Redshank
populations were most affected by raptor predation; over 50 % of the
total population (which was found to be closed during most of the
winter) and over 90 % of the juvenile population were taken in two
winters: juveniles were more likely to be killed by raptors.
Cresswell, W. (1996):
Surprise as a winter hunting strategy in Sparrowhawks Accipiter
nisus, Peregrines Falco peregrinus and
Merlins F. columbarius. Ibis 138: 684 - 692.
Davidson, N. C. (1983):
Formulae for estimating the lean weight and fat reserves of live
shorebirds. Ringing & Migration 4: 159-166.
Formulae for calculating the lean weight
and fat reserves of shorebirds from their total body weight and
wing-length and / or bill-length are given for six species wintering in
Britain. General formulae for shorebirds in various seasons and areas
are also given. The application of these, and other published formulae,
for estimating lean weight is discussed. Formulae derived from single
species should be used whenever possible. A better estimate of lean
weight is obtained from formulae using both wing-length and bill-length
than from formulae using only one of these. The general formulae can be
used when a single-species formula is not available.
CP:In Dunlin the formulae
using bot wing- and bill-length are slightly better than formulae using
only bill-length. 40 ad, NE England in winter: LW = (0,005WL + 0,015BL
+ 2,58)3, 32 juv, same conditions: LW = (0,011WL
+ 0,012BL + 2,02)3.
Davidson, N. C. (1984):
How valid are flight range estimates for waders? Ringing &
Migration 5: 49-64.
Assessments of fat loads and flight ranges
are important in studies of migration phenology. Departure condition,
which is an essential input for flight range calculations, is difficult
to measure accurately, especially for live birds. Problems arise from
the estimation of fat load and the rate of fat storage, water loss, and
departure time. Flight range models give range estimates for waders
differing by up to 2.5 times for the same fat load. The validities of
the models are tested against known migrations of waders. Ranges in
still air from flight metabolism models (McNeil & Cadieux 1972,
Greenewalt 1975, Summers & Waltner 1979, this study) predict
observed range most accurately. However, range modifiers, particularly
wind speed and direction, altitude, flight speed, and aerodynamic drag,
will all increase predicted range, when applied to waders. With
information on actual conditions of migration, Pennycuick's (1975)
aerodynamic model may be the best range predictor. Since range
modifiers are difficult to apply, flight range can be approximated by
calculation of a still-air range from the flight metabolism model
derived in this paper. Before they are used for other groups of birds,
models should be tested against known migration of these groups.
CP: In an Appendix four
different formulas for calculating distances are presented, in addition
there is a BASIC-program for the same formulas.
Davidson, N. C. (1984):
Changes in the conditions of dunlins and knots during short-term
captivity. Can. J. Zool. 62: 1724 - 1731.
Davidson, N. C., Uttley, J. C.
& P. R. Evans (1986): Geographic variation
in the lean mass of dunlins wintering in Britain. Ardea 74: 191 - 198.
Dekker, D. (1998):
Over-ocean flocking by dunlins, Calidris alpina,
and the effect of raptor predation at Boundary Bay, British Columbia.
Can. Field-Nat. 112: 694-697.
Dierschke, V. (1994):
Timing of occurrence and fluctuations in abundance of Calidris
sandpipers staging on the island of Helgoland, SE North Sea. Vogelwelt
115: 59 - 68.
The seasonal patterns of occurrence and
year-to-year variation in abundance of staging Calidris
sandpipers on Helgoland were analysed. One to two hundred Purple
Sandpipers C. maritima winter annually. Of all
other species few birds rest during spring and adult autumn migration,
but high numbers occur during juvenile autumn migration. The numbers of
juveniles show annual fluctuations, expressed as a juvenile index (sum
of maximum counts of all five-day-periods during juvenile migration per
year). Coincidence of fluctuations in juvenile index of Calidris
species and percentage of juveniles in Dark-bellied Brent Geese Branta
b. bernicla wintering in Central Europe suggest that the
juvenile index indicates the breeding success in the Arctic. There is a
high coincidence of breeding success between the Taimyr-breeding
species Knot Calidris canutus, Sanderling C.
alba, Curlew Sandpiper C. ferruginea
and Brent Goose, all of which produce low number of juveniles
approximately every third year. This is less pronounced in Dunlin C.
alpina and Little Stint C. minuta,
probably because of the larger breeding area from which these birds
originate. In demonstrating a very poor breeding success in the four
Taimyr breeding species every three years, the Helgoland data support
the hypothesis of Roselaar (1979) and Summers (1986) about the
correlation between breeding success of arctic waders and geese and
cyclic changes in lemming abundance. In years following peak lemming
abundance high predation pressure causes catastrophic losses of eggs
and young in Taimyr breeding waders and geese. Counts on Helgoland can
be used to monitor breeding success of Arctic breeding waders, because
here surveys can be conducted more efficiently than in the Wadden Sea
and reflect a representative sample of the migration in these species.
Dierschke, V. (1996):
Unterschiedliches Zugverhalten alter und junger
Alpenstrandläufer Calidris alpina:
Ökologische Untersuchungen an Rastplätzen der Ostsee,
des Wattenmeers und auf Helgoland. Dissertation, Göttingen. (Differential
migration in adult and juvenile Dunlins: ecological studies at staging
sites of the Baltic Sea, the Wadden Sea and Helgoland.
Here follows the first block of the Summary;
blocks 2 - 3 concern food, 4 foraging rhythms, 5 fat deposition rates,
6 intraspecific competition, 7 predation, 8 site tenacity).
In July and Auugust, most adult Dunlins
migrate fast and directly from their breeding area in northern Eurasia
to staging areas in the Wadden Sea and the Wash, where they conduct or
complete their post-nuptial moult. Juveniles
follow later, more slowly and independently from adults.
Instead of concentrating in moulting areas they disperse over European
coasts and are first found mainly at the Baltic Sea and along the
Norwegian coast. Juveniles ringed at the latter two areas behave
different in selecting moulting areas as adults in later years.
Juveniles migrating northerly are found mainly in the Wash, those
migrating southerly mainly in the Wadden Sea. It is proposed that
experiences during the first year of life are responsible for the
selection of a moulting area. To test this hypothesis I investigated
different ecological aspects of wader habitats in the Wadden Sea, at
the southern coast of the Baltic (Hiddensee, Langenwerder) and at the
island of Helgoland (German Bight, SE North Sea), which could explain
why Dunlins do not come back to their juvenile stopover sites at the
Baltic and at Helgoland.
CP: I disagree with
Dierschke on many points concerning migration, and I think that his
idea of "independent migration of juveniles" must have been launched
against his own better knowledge, there must be data from Langenwerder
showing him otherwise. The whole situation reminds me of the hidden
anomalies of the Ptolemaian cosmology: in the present case every
serious worker from the Baltic area knows that adults do accompany
juvenile migrating Dunlin throughout the autumn, but they "are not
there" because juveniles migrate on their own in the cosmology of
Dierschke, V. (1998):
High profit at high risk for juvenile Dunlins Calidris alpina
stopping over at Helgoland (German Bight). Ardea 86: 59-69.
During autumn migration, up to 1100
juvenile Dunlins Calidris alpina per day forage
on the island of Helgoland (SE North Sea). Beds of washed up wracks and
kelp are used as a feeding habitat where they take kelp fly larvae
(Coelopidae) at a high rate (17.8 larvae min-1).
This high energy intake allows rapid fattening (1.7-3.3 g day-1)
and short lengths of stay (about 4-5 days), leading to a high daily
turnover of individuals (0.2-0.7 day-1). Despite
the good conditions for meeting energetic requirements, staging at the
island incurred a high predation risk from migrating birds of prey.
Different feeding priorities might be one reason why most adult Dunlins
avoid Helgoland as a staging site and instead aggregate at large
staging areas such as the Wadden Sea, where individual depredation risk
is more than 50 times less.
Dierschke, V. & A. J.
Helbig (1999): Baltic Sea windflats as spring
staging site for Dunlins Calidris alpina. Wader
Study Group Bull. 90: 42-46.
From March and April onwards, about 3,000
- 6,000 Dunlins Calidris alpina stage before
spring migration in three windflats at the island of Hiddensee (German
Baltic coast). In the evening hours between 27 May and 3 June, most
birds depart in flocks of 10-500 birds in a north-north-easterly
direction. The late departure indicates that these birds belong to
Siberian breeding populations. Due to the
lack of ringing recoveries it is not known whether the spring staging
Dunlins from the Baltic belong to populations wintering along the
European Atlantic coast or in the western Mediterranean Sea.
Dierschke, V., Kube, J., Probst,
S & U. Brenning (1999): Feeding ecology of
dunlins Calidris alpina staging in the southern
Balic Sea, 1. Habitat use and food selection. J. Sea Res. 42: 49 - 64.
Dierschke, V., Kube, J.
& H. Rippe (1999): Feeding ecology of
dunlins Calidris alpina staging in the southern
Balic Sea, 2. Spatial and temporal variations in harvestable fraction
of their favourite prey Hediste diversicolor. J.
Sea Res. 42: 65 - 82.
Spatial and temporal variations were
studied in the distribution of the fraction of the polycaete Hediste
diversicolor harvestable for dunlins under non-tidal
conditions in Baltic Sea windflats. The investigations were carried out
in 1991 and 1995 near the island of Hiddensee, in the Bock and Bessin
windflats, the most significant staging areas for shorebirds on the
southern Baltic Sea coast. Density and biomass distribution patterns of
H. d. were found to be determined by exposure
time, but not by sediment parameters. Whereas the density distribution
and the size-frequency distribution patterns of H. d.
showed large spatial and seasonal variation in the Bock windflat, both
parameters showed little spatial but obvious seasonalvariability in the
Bessin windflat. Active migration and passive bedload transport are
considered to be the most important causes of the observed differences.
When the sediment was inundated or still wet after an emersion, H.
d. lived in the top 3 cm of the sediment. The low level of
surface activity observed, and the low organic matter values of the
sediment suggest that filter feeding was the most common feeding mode
of H. d. in the study area. H. d.
retreated to deeper layers when the sediment became dry. No
correlations were found between numbers of dunlins and density or
biomass of H. d.. Dunlins selected their foraging
habitat according to substrate conditions and preferred shallow water
and recently emerged sandflats. As a consequence, dunlins foraging in
windflats were usually concentrated in dense flocks in the shallow
water surrounding these exposed sandflats. Feeding conditions varied
between sites and depended mainly on the topography of the windflat and
its water-current regime. High densities of feeding dunlins can locally
cause heavy exploitation of the standing stoch of H. d.
during prolonged periods of constantly low water. However, the
availability of several windflats in the study area around the island
of Hiddensee at slightly different levels compared to mean sea level
allows the shorebirds to switch between sites, and therefore to make
use of a spatially and temporally enlarged supply of harvestable prey.
DOF. Fugle på Sjaelland.
(1986 - 1993): (Annual Report from Sealand)
Dugan, P. J. (1981):
The importance of nocturnal foraging in shorebirds: A consequence of
increased invertebrate prey activity. In N. V. Jones and W. J. Wolff
(eds.): Feeding and survival strategies of estuarine organisms, pp.
251-260. Plenum Press, New York.
Edelstam, C. (1972):
The visible migration of birds at Ottenby. Vår
Fågelvärld, suppl. 7.
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
Engelmoor, M., Roselaar, C. S.,
Boere, K. & E. Nieboer (1983): Post-mortem
changes in measurements of some waders. Ring. & Migr. 4: 245 -
Engelmoor, M. & C. S.
Roselaar (1998): Geographical Variation in Waders.
Kluwer Ac. Publ. With a diskette containing data and an auxiliary
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
The populations breeding between N Fennoscandia and the Kolyma Delta
are evidently polymorphic. The N Fennoscandia - Yamal population
differed from both the Taymyr- and the Anabar-Kolymsk population,
whilst both latter were nearly always indistinguishable in the
morphometric analyses. We conclude on the recognition of 2 taxa in this
region: the western 'alpina' type is characterized
by (1) smaller dimensions, (2) lack of 'adult buff' wing coverts, (3)
narrow white edges along the outer vanes of the primaries and (4) the absence of primary moult on the breeding
grounds; the eastern 'centralis' type
is larger, has 'adult buff' coverts, more white on the vanes and starts
primary moult during breeding. This difference is supported by mtDNA
research (Wenink et al. 1996) These are good reasons to distinguish
both as separate subspecies.
Evans, P. R. (1964):
Wader measurements and wader migration. Bird Study 11: 23 - 38.
Evans, P. R. (1986):
Correct measurement of the wing-length of waders. Wader Study Group
Bull. 48: 11.
The suggested steps are: 1. Press wing firmly against end-stop of
wing-rule. 2. Straighten curve of wing. 3. Stroke along feathers to
Evans, P. R., Goss-Custard, J. D.
& Hale, W. G. (eds.) (1984): Coastal waders
and wildfowl in winter. Cambridge: Cambridge University Press.
Ferns, P. N (1978):
The onset of prebasic body moult during the breeding season in some
high-Arctic waders. Bull. Br. Orn. Club 98: 118 - 122. No summary;
field-work in NE Greenland, "prebasic" = postnuptial.
"None of the 11 C. alpina
captured showed any trace of prebasic moult, but they were all captured
close to the date when their eggs hatched. This species undergoes the
whole of the prebasic moult on the breeding grounds in some regions
(Holmes 1971), so it is particularly surprising that none was recorded
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
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
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
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,
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
Goede, A. A., E. Nieboer
& P. M. Zegers (1990): Body mass increase,
migration pattern and breeding grounds of Dunlins, Calidris alpina,
staging in Dutch Waddensea in spring. Ardea 78: 135 - 144.
Though a lot is known about the Dunlin, a
highly variable wader species in many respects, there is still
uncertainty whether substantial numbers of this species migrating
through W. Europe in spring, breed as far as Siberia. Data on numbers,
turnover, recoveries, body mass and bill length of the Dunlin,
collected in spring in the eastern part of the Dutch Wadden Sea, are
presented. Two kind of fattening strategies are clearly distinguished
and seem to be used by two different groups of the subspecies alpina.
The groups are temporarily segregated: one is present in April the
other in May. It is argued that the latter one breeds in Siberia as far
as the western part of the Taymyr peninsula.
CP: This paper relies too
much on the representativity of Baltic catches where juveniles are
involved, in my view all conclusions concerning autumn conditions are
incorrect. It should be revised, or the topic should be treated anew.
Goss-Custard, J. D.
(1969): The winter feeding ecology of the Redshank Tringa
totanus. Ibis 111: 338 - 356.
Greenwood, J. G. (1979):
Geographical Variation in the Dunlin Calidris alpina (L.). Ph. D.
Thesis, Liverpool Polytechnic.
Greenwood, J. G. (1983):
Post-nuptial primary moult in Dunlin Calidris alpina.
Ibis 125: 223 - 228. No abstract, but the discussion
opens with the following statement:
Two conclusions may be
drawn from this study. First, there are differences between populations
in the starting date of post-nuptial primary moult in Dunlin moulting
on the breeding grounds. Secondly post-nuptial primary moult occurs on
the breeding grounds only in populations to the east of the Ural
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:
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.
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.
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.
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
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
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
Haukioja, E. (1971):
Processing moult card data with reference to the chaffinch Fringilla
coelebs. Orn. Fenn. 48: 25 - 32.
Van der Have, T.M. & V.
van den Berk (1994): De mediterrane trekroute: een
netwerk van wetlands voor watervogels. Limosa 67: 159 - 162.
The Foundation Working Group International
Waterbird and Wetland Research (WIWO) stimulates and supports
initiatives of volunteers to study tthe distribution and migration
ecology of waterbirds for the benefit of nature conservation in
theAfro-Palearctic migration system. Traditionally, projects focused on
waterbirds migrating within the East-Atlantic Flyway, but in recent
years attention has been extended to the Mediterranean region. These
studies aimed to reveal more of the loop-migration of several wader
species and to make acomparison between the major wetland types of both
flyways. One of the characteristic
wetland types of the Mediterranean Flyway is "windflat", that is,
mudflat exposed by wind force. The largest system of windflats is found
in the Sivash, a lagoon system in the Crimea near the Sea of Azov,
Ukraine. In some brackish lagoons invertebrate densities equal those of
tidal wetlands and these wetlands were found to be of international
importance for arctic waders in general, and in particular for at least
one third of the European population of Broad-billed Sandpipers Limicola
& S. Sunada (1999): On the aerodynamics of
moult gaps in birds. J. Exp. Biol. 202: 67 - 76.
Helbig, A.J., Dierschke, V.
& R. Barth (1994): Ornithologischer
Jahresbericht 1993 für Hiddensee und Umgebung mit
Nachträgen zum Jahr 1992. Ber. Vogelwarte Hiddensee 11: 51 -
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
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
One hundred and four wings showed evidence of suspended
primary moult, and most (82 %) of these suspensions occurred with six
or seven new primaries in the wing. Nearly all (92 %) of these
suspensions were found in birds collected in the last half of August
and the first half of September. In these two periods respectively 13 %
and 14 % of the birds had suspended primary moult.
The secondaries were moulted in two groups. The moult of the
first eleven, numbered from the wrist (S1-S11), most often started with
the shedding of S1 or one of the two feathers S10 or S11. After the
termination of the primary moult most birds had new S1 and S11, but the
rest of these secondaries, and especially those in the centre of the
row, were moulted to a lesser extent. On
the average a little more than five of these eleven secondaries were
moulted every year.
The sequence of moult in the tertials (S12-S15) was quite
irregular and much individual variation concerning the onset of this
moult was evident. Some birds initiated the tertial moult with the loss
of the innermost primary, others not until the sixth primary was fully
grown. Usually one or two tertials were growing at a time and
suspensions were common, occurring in 207 of 526 birds with from one to
three new tertials.
(...) The mean duration of primary moult in the individual
bird was 101 days, and the total moulting period of these feathers
covered 158 days.
...a complete separation of primary moult in the Golden
Plover from breeding and migration would add to the enhanced
difficulties of winter survival, compared to estuarine wintering waders
in Europe, this species seems to experience. It is shown that about
half of the Golden Plovers would have to complete the primary moult in
December as a result of such a postponement. This late completion of
moult, involving the long outer primaries, would coincide with a period
of building-up of nutritional reserves and with cold-weather movements.
Holgersen, H. (1963):
Tre tillegg til den norske fuglefauna. Sterna 5: 225 - 228.
Holmes, R.T. (1966):
Molt cycle of the Red-backed Sandpiper (Calidris alpina)
in western North America. Auk 83: 517 - 533.
In breeding populations of C.
alpina in northern Alaska (71 ° N), the prebasic
molt of adults is condensed int the short span of the arctic summer and
overlaps with almost the whole of the breeding season. Molt begins
early in the summer, and new flight feathers are completely grown
before departure for winter quarters. At lower-latitude breeding
localities in western Alaska (60-66° N), molt apparently starts
later and breeding begins earlier than at higher latitudes, with the
result that less overlap occurs. Even in the northern populations,
however, the major portion of energy expenditure on molt comes in late
summer when breeding is over and young Red-backs are fully grown.
Molt takes place during slow phases of
both fall and autumn migrations, energy reserves evidently being
sufficient to support both activities. In periods of rapid migration,
molt is suspended.
The specialization in the molt schedule of C. alpina
relate to the fact that this species, with its winter quarters in
north-temperate regions, remains in the arctic through the end of
summer, during which time it exploits tundra food sources in the
absence of possible competitors.
Holmes, R.T. (1966):
Feeding ecology of the Red-backed Sandpiper (Calidris alpina)
in arctic Alaska. Ecology 47: 32 - 45.
Holmes, R.T. (1969):
Differences in population density, territoriality, and food supply of
dunlin on Arctic and subarctic tundra. - In: Watson, A. (ed.), Animal
populations in relation to their food sources. Blackwell, pp. 303-317.
Holmes, R.T. (1971):
Latitudinal differences in the breeding and molt schedules of Alaskan
red-backed sandpipers (Calidris alpina). Condor
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
The material is faulty: incomplete, (both materials are faulty), and
the authors look at captive birds, showing practically zero remige
growth, without reacting. The whole paper is ruined by one very common
presupposition: that Dunlin essentially migrate and
moult at the same time. Holmgren brings this error on to
Rösner 1997, and further still. He should be stopped and
brought to some basic level of insight, and it should be done now.
Horvath, L. & A. Keve
(1956): (transl.) The subspecies of Dunlin in Hungary. Ann.
Hist. Nat. Mus. Hungary N.S. 7: 469 - 476.
Jehl, J. R. & B. G. Murray
(1986): The evolution of normal and reverse sexual size
dimorphism in shorebirds and other birds. In: Johnston, R. F. (ed.),
Current Ornithology. Vol. 3. Plenum Press, New York and London, pp. 1 -
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:
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):
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
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
In 20 of the 24 species of calidridines, sexual dimorphism
in body size varies from 0.86 to 1.00, in bill length from 0.85 to
1.00, and in tarsus length from 0.94 to 1.01. In the remaining four
species those ratios are, respectively, 1.15, 1.03, 1.06 for C.
acuminata, 1.19, 1.08, 1.11 for T. subruficollis,
1.37, 1.08, 1.08 for C. melanotos, and 1.77,
1.15, 1.23 for P. pugnax. In
the 20 species with reverse dimorphism, the territorial and courtship
displays often involve prolonged aerial flights of some complexity.
In the four species with normal dimorphism, there is a reduction in or
lack of aerial display and an increase in the degree of polygyny.
Johnson, C. & C. D. T.
Minton (1980): The primary moult of the Dunlin Calidris
alpina at the Wash. Orn. Scand. 11: 190 - 195.
The primary moult of the Dunlin Calidris
alpina at the Wash, East England, is described. A new
statistical method for estimating the duration of the moulting period
of a population is developed and individual moult duration is also
considered, using population parameters and data from retraps.
Differences were found in the timing and duration of moult season in
different years. Within any one year late moulting individuals moulted
more rapidly than early birds. The adaptive significance of these
differences within the annual cycle is discussed.
CP:This paper deals mainly
with the progression of moult within the population,
the authors stating that "...it
is expected that a sigmoid curve will fit the data better than a linear
model" "...an estimate of the average moul
duration for the individual was obtained by considering the median
moult scores of the population (Appleton and Minton 1978)."
The moulting rate grew from 1.1 in birds caught before 15 July to 1.3
in birds caught 16-31 July and 1.5 in birds caught 1 - 15 Aug, the
growth rates gradually fell to 0.7 - 0.8 when birds approached the
final stages of moult.
Johnson, C. (1985):
Patterns of Seasonal Weight Variation in Waders on the Wash. Ringing
& Migration 6: 19-32.
Analysis of weight variation, based on
monthly mean weights for ten wader species occurring on the Wash
demonstrating the patterns of season weight variation. For each species
the trends are interpreted in terms of adaptations and responses to
specific life cycle events and potential feeding difficulties which
arise from winter environmental conditions.
Jönsson, P. E.
(1986): The migration and wintering of Baltic Dunlins
Calidris alpina schinzii. Vår Fågelvärld.
Supplement 11: 71 - 78. This paper has no abstract.
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
In a South Swedish population of Dunlins,
males were on average smaller than females. Differences were most
pronounced in bill length and body mass. Males arrived at the breeding
sites in spring on average 12 days earlier than females, with a
tendency for large and long-billed females to arrive earlier than small
and short-billed females. A significant positive correlation between
date of arrival and start of egg-laying was found in females, but not
in males.Previously mated pairs started egg-laying on average 4 days
earlier than newly formed pairs. Disassortive mating in relation to
size was found in new pairs, so that small and short-billed males, and
large and long-billed females nested earlier than average-sized birds.
A significant positive correlation was also found between female size
and mean egg volume. To explain the observed pattern of mating and
sexual size dimorphism, I suggest a combination of sexual and natural
(ecological) selection. Small size in males may be energetically
advantageous durin aerial display and male parental care. Short bills
may be selected for when males are feeding in terrestrial habitats
during brood-rearing. In females, selection for large size and long
bill is probably associated with the production of larger eggs and more
efficient feeding in marine littoral habitats, respectively. Selection
may also favour large females in intra-sexual competition for mates and
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
Kania, W. (1990):
The primary moult of breeding Dunlins Calidris alpina
in the central Taimyr in 1989. Wader Study Group Bull. 60: 17 - 19.
Kaukola, A. & I. Lilja.
(1972): Migration of Calidris and Limicola
species at Yyteri in 1961 - 69. Porin Lint. Yhd. Vuosikirja 1972: 17 -
23 (In Finnish with English summary).
King, J. R. (1981):
Energetics of avian moult. Proc. 17th Int. Orn. Congr. 312 - 317.
Klaassen, M. & B. J. Ens
(1990): Is salt stress a problem for waders wintering on the
Banc d'Arguin, Mauritania? Ardea 78: 67 - 74.
Kolthoff, G. (1896):
Zur Herbstwanderung der nordischen Sumpfvögel über
die Insel Öland. Festskrift för Liljeborg, 121 - 136.
Krol, E. (1985):
Numbers, reproduction and breeding behaviour of Dunlin Calidris alpina
schinzii at the Reda mouth, Poland. Acta orn. 21: 69 - 94.
Kube, J., H.-U. Rösner,
H. Behmann, U. Brenning & J. Gromadzka (1994):
Der Zug des Alpenstrandläufers (Calidris alpina) an der
südlichen Ostseeküste und im Schleswig-Holsteinischen
Wattenmeer im Sommer und Herbst 1991. Corax, Sonderheft 2: 73 - 82.
In the late summer and autumn of 1991
migrating Dunlin (Calidris alpina) were counted along the south Baltic
coast and in the Waddensea parts of Schleswig-Holstein. In all Baltic
areas there were three waves of
migrating adults and one wave of migrating juveniles. A
sharp rise in Waddensea numbers coincides with the first Baltic wave of
adults, a second rise in September with the wave of juveniles. Based on
estimates of the maximum amount of resting adults and juveniles along
the Baltic shores, and catching results from the mouth of Vistula
(Poland) and the isle of Langenwerder, a minimum value for the overall
passage of migrant Dunlin in this area can be calculated. Relatively
few adults visit German and Polish shores: only 1 - 2 % of the total
population, while more than 10 % of the juvenile population stays for
some time in the same area.
Kus, B. E., Ashman, P., Page, G.
W. et al. (1984): Age related mortality in a
wintering population of dunlin. Auk 101:
Lane, B. & A. Jessop
(1985): Tracking of migrating waders in north-western
Australia using meteorological radar. Stilt 6: 17 - 28.
Leslie, R. & C. M.
Lessells (1978): The migration of Dunlin Calidris
alpina through northern Scandinavia. Orn. Scand. 9: 84 - 86.
Observations made on the Varangerfjord,
N.E. Norway, during 1974 indicate that there is a large Dunlin passage
through the area. Ringing recoveries suggest that juveniles which pass
through the area during August move down the west coast of Norway,
whilst adults, moving through during July, take a more easterly route,
moving overland to the Gulf of Bothnia and into the Baltic.
CP:This is a stenographic,
non-transparent paper, representing the worst of the British tradition
(later on in particular: Bird Study) by this time. The suggestions by
the authors have been treated as statements when quoted, but none of
these statements can be critically assessed. A "juvenile route" along
the Norwegian west coast was established here, adults were said to be
channeled by way of the Baltic - and all problems, difficulties,
complications were swept under the carpet. I would very much
like to see juv : ad ratios from the Norwegian west coast, I would like
to see figures describing the overall catching period, and I would like
to know if this catching period coincides with the migration period of
Dunlin in Norway. And: is the age-determination of late
Dunlin reliable in the Norwegian case?
& T. Piersma (1993): Mass change in
migrating birds: the evidence for fat and protein storage re-examined.
Ibis 135: 70 - 78.
Visser, G. H. & S. Daan (1993): The
energetic cost of feather synthesis is proportional to basal metabolic
rate. Phys. Z. 66: 490-510.
(...)The cost of feather synthesis was
estimated at 836 and 683 kJ per (g dry feathers) in the bluethroats and
redpolls, respectively. (...) The Cf for a
species with known BMRm may be estimated from
the equation Cf = 270BMRm.
Species with a relatively high BMRm for their
size also have a relatively high Cf. The tight
association of Cf and BMRm
between species, and the low efficiency values of feather synthesis,
suggests that feather production costs include more than the costs for
keratin synthesis: they mainly consist of costs of maintaining tissues
necessary for feather production.
P. (1958): Storleksskillnader hos
genomsträckande kärrsnäppor (Calidris
alpina) vid Ottenby. Vår Fågelvärld 17:
287 - 301. This paper has a summary, part of it is quoted here.
Measurements of bill, wing, and total
length of 1.112 dunlins (99 % juvenile birds of the year) trapped for
ringing at Ottenby bird station, on the island of Öland,
during three weeks in August and September 1957 show that considerable
differences in size exist between birds from the earlier and birds from
the later part of this period.
This was demonstrated by splitting the material into three groups, each
representing a period of one week: 26 Aug. - 1 Sept. (443 inds.), 2 - 8
Sept. (322 inds.), and 15 - 21 Sept. (347 inds.); no measurements were
taken between Sept. 8 and 15. (...) While
bill-size proved very uniform between the three groups, there was a
small but quite significant decrease in winglength between the first
two periods and the last and a very appreciable increase in total
length at the same time.
It was evident from the distribution of the measurements - especially
the total lengths - that the last group was heterogeneous. For that
reason a very late group was picked out of the material, namely 150
birds chosen at random from those trapped 19 - 21 September. Similarly
a very early group was selected, namely 150 birds chosen at random from
those trapped 27 - 28 August. (...)
The conclusions drawn from the preliminary analysis are further
strengthened by this treatment. There is a remarkable conformity in bill-length
between early and late birds. The frequency distribution of
measurements in each group is close to normal, which indicates that the
difference in bill-length between the sexes, known from museum studies
on the Dunlin, is not very pronounced in the present material of young
birds. The wings of August birds are about 3 mm
longer on the average than those of September birds (and this
difference) is highly significant. Etcetera, etcetera.
This is an old paper, an antique. What I like about it is the fact,
that it is transparent; the conclusions can be checked, this is not
always the case when it comes to papers based on Ottenby material. The
sampling intervals seem a little "forced", but there is no way telling
if this also lies behind the "non-committal" of the conclusions. What
everybody would like to see from Ottenby is large, coherent
materials - moult, biometry - covering the whole of the migration
period, without any kind of calendar compulsion or possible influence
from measuring techniques.
Mascher, J. (1966):
Weight variation in resting Dunlins (Calidris a. alpina) on autumn
migration in Sweden. Bird-Banding 37: 1 - 34. This paper has a long
summary, I choose to quote points 2, 4 and 5.
2. As is clear from the
recapture figures, the passage proceeds much faster early in the season
than later. In 1963, only 14.5 per cent of the adults were retrapped as
compared to nearly 30 per cent of the later-arriving juveniles. Very
few adults stayed more than 2-3 days, whereas 18.3 per cent of all
recaptured juveniles lingered more than 8 days. (...)
4. An increase in total weight of 0.50 gm per mm
wing length was found in the juveniles. This is appreciably more than
the figures applying to medium-sized and larger passerines. In adult
Dunlins, a somewhat smaller increase amounting to 0.41 gm per mm wing
length was found, but the difference is barely significant.
5. The lowest weight records obtained were probably
near the fat-free weight of the subspecies C. a. alpina,
which is likely to average about 34-35 gm. Some fat-free data on the
larger sakhalina subspecies averaged about 5 gm
more than the fat-free weight calculated for the corresponding wing
length in C. a. alpina. The maximum fat
deposition in Dunlins resting at Ledskär amounted to 20-25 gm
fat or 40 per cent of total body weight, which is in accordance with
data published on passerine migrants.
Mascher, J. & V.
Marcström (1976): Measures, weights, and
lipid levels in migrating Dunlins Calidris a. alpina L. at the Ottenby
Bird Observatory, South Sweden. Ornis Scand. 7: 49 - 59.
Measurements, weights, and lipid levels of
85 Dunlins collected during two autumn seasons at the Ottenby Bird
Observatory in South Sweden were analyzed. Males had significantly
shorter wings and bills, and lower body weights than females. Fat
depots ranged from about 5 to 30 per cent of total weight an accounted
for the major variations in body weight. No correlation was found
between body size and lipid level. The water content expressed as a
percentage of fat-free weight was virtually constant within each year
sample, irrespective of body size and lipid level. Significant
differences in fat-free dry weights and water content between the two
year samples were found. A formula for calculation of fat stores from
total weight and wing length is presented. The results are compared to
other work on waders and passerines.
McEwan, E. H. & P. M.
Whitehead (1984): Seasonal changes in body weight
and composition of Dunlin (Calidris alpina). Can.
J. Zool. 62: 154 - 156.
McNeil, R. & F. Cadieux
(1972): Numerical formulae to estimate flight range of some
North American shorebirds from fresh weight and wing length.
Bird-Banding 43: 107 - 113.
Meissner, W. (1998):
Fat reserves in Dunlins Calidris alpina during autumn migration through
Gulf of Gdansk. Orn. Svec. 8: 91 - 102.
To describe fat reserves in adult and
juvenile Dunlins during autumn migration in the Gulf of Gdansk,
multiple regression equations for estimating fat mass in Dunlins were
derived. The average fat level in a particular wave of migrants depends
on many factors. Low amount of accumulated fat suggests that this
species migrates along the southern Baltic in small steps, similarly to
the rest of Europe. The interpretation of the results is difficult
because at least two distinct migration routes cross the Gulf of Gdansk
region. Dunlins starting their primary moult had lower fat index than
birds in advanced stages of moult. The rate of fattening in Dunlin
depends on the quality of the feeding place (higher in the sewage farm
than in the river estuary). Birds which stayed longer in the feeding
area had, on average, lower fat mass increments than those leaving Gulf
of Gdansk after a short stay. Birds with low fat mass started putting
on weight immediately, whereas "fat" birds lost weight at the
beginning. Those results confirmed Mascher's (1966) hypothesis about
differences in body mass change rate during the first day of stay in
birds with low and high fat reserves. The level of free fatty acids in
the blood appears to be a factor controlling this pattern. Differences
in fat accumulation between Ottenby (southern Sweden) and Gulf of
Gdansk are discussed.
CP: 426 out
of 8443 = 5.0 % Dunlins caught at Rewa and 140 out of 1685 = 8.3 % at
adjacent Jastarnia had scores 49 - 50 (i.e. complete wing). In
all, 5.6 % of all adults passing the Rewa area had performed a complete
moult on or near breeding-grounds, they migrated with fresh remiges.
And these completely moulted adults accompany juveniles, in Poland till
the catch is ended prematurely in late September, in the Sound area
until the last migration waves in October. I do
not expect anyone to suggest seriously, that the Polish birds had
returned from moulting grounds in the Waddensea. (I had this suggestion
in connection with late adults at Langenwerder). This note is saved
here for reference.
Also note the remark: Data from birds retrapped in the Rewa
region show that many are in active moult (unpublished data), as occurs
on the Swedish coast (Holmgren et al. 1993). This is the
same vague way of self-quotation as in Holmgren et al. 1993b!
I have a question here: Catches
reveal different stages of moult at Rewa - but what do retraps
show? A score of adults has rested for more than a week. This
material could be very important - but is it conclusive?
Meltofte, H. & J.
Rabøl, (1977): Vejrets indflydelse
på efterårstrækket af vadefugle ved
Blåvandshuk, med et forsøg på en analyse
af trækkets geografiske oprindelse. DOFT 71: 43-63.
Meltofte, H. & P. Lyngs,
(1981): Spring migration of waders Charadrii
at Blåvandshuk, Western Denmark, 1964-1977. DOFT 75: 23-30.
Excerpt from the summary.
(...)In Limosa limosa
and Calidris alpina, together with more usual
occurrences of Calidris canutus, the main part of
the movements pass south, and mainly in the morning hours. This
migration is probably made up of birds passing the southern part of the
North Sea on their way to the northern part of the Wadden Sea. Most
birds are seen in southerly winds and low visibility, thus probably
having drifted a little north during the passage.
In Haematopus ostralegus, Limosa lapponica and Calidris
alpina two distinct peaks are seen during spring. It is
concluded that these are made up of different populations. (...) In Limosa
lapponica and Calidris alpina they may
be populations having wintered in West Europe and West Africa,
respectively, and which arrive in the Wadden Sea at different times,
the African wintering population arriving later than the European
Meltofte, H. (1993):
Vadefugletrækket gennem Danmark. DOFT 87: 1 - 180. Short
excerpts of the Dunlin text are quoted here.
p. 66: It is not
possible to separate the migration of European and Siberian birds, but
as the migration culminates c1 week earlier in SW Finland, at Ottenby
and S. Amager (Copenhagen, Sealand) than at Blåvand (W
Jutland) (Fig. 23; Edelstam 1972, Kaukola & Lilja 1972), it is
probable, that North European breeding birds migrate a little earlier
than Siberian. Wader migration at Blåvand generally has a
higher share of Arctic populations than Baltic sites (Meltofte
& Raböl 1977). And the ringing material from the Dutch
Waddensea indicates, that European breeding birds to a higher extent
migrate by way of the Baltic (Goede et al. 1990).
p. 70: During the culmination of juvenile migration,
in September-October, some 250000 - 350000 Dunlin are regularly present
in the Danish part of the Waddensea, and occurrances exceeding 400000
have been noted twice. These are very high numbers compared with the
remaining parts of the Waddensea, and the same applies to spring, The
maximum number in Schleswig-Holstein is 300000, in Niedersachsen
290000, in Holland 274000 (Smit & Wolff 1981, Zegers &
Kwint 1992, J. Blew and H.-U. Rösner in litt.) In other parts
of Denmark some 40 - 50000 birds are resting during the same period.
Meltofte, H., J. Blew, J.
Frikke, H.-U. Rösner & C. J. Smit (1994):
Numbers and distribution of waterbirds in the Wadden Sea. Results and
evaluation of 36 simultaneous counts in the Dutch-German-Danish Wadden
Sea 1980-1991. IWRB Publication 34, WSG Bulletin 74, Special issue.
(from text) Our mid-winter counts have
yielded totals of between 131,000 and 258,000 during mild winters. Of
these, up to 210,000 have actually been counted. Considerably less
Dunlins remain during severe winters, when we recorded between 23,400
nd 62,200. In mild winters, the Dunlins are surprisingly evenly
distributed throughout most of the Wadden Sea, where they predominantly
feed on silty flats (Ens et al. 1993). In severe winters, the Danish,
German, and eastern parts of the Dutch Wadden Sea are largely deserted.
In January 1992 a record 78,000 Dunlins were found in the
Schleswig-Holstein Wadden Sea (Rösner unpubl.).
In spring, large numbers of Dunlins start to move into the Wadden Sea
from late February onwards. These are birds that have wintered further
west and south in Europe, which go to the Wadden Sea to moult into
breeding plumage and build up body reserves for the onward migration.
Numbers increase in most areas during March and April, until a new
influx of birds apparently takes place in early May. There are
indications that the Dunlins arriving in March and April are European
sub-arctic breeders, while those passing in May breed in Siberia (Goede
et al. 1990, Meltofte 1993). Acording to our counts, more than 4000,000
Dunlins may be present in the Wadden Sea already by March. Numbers
increase to between 804,000 and 1,120,000 during our best counts in the
first half of May, when birds from the whole breeding range are
supposed to be present. Of these up to 1,046,000 Dunlins were actually
counted. With 50,000-100,000 Dunlins
staging in other parts of Denmark and 15,000-35,000 in the Dutch Delta
(Meininger & van Haperen 1988, Meininger et akl. 1994),
this means that up to about 90 % of the West European/West
Mediterranean alpina Dunlins could be present in
the Wadden Sea countries at this time. As some hundreds of thousands
may fly north via South-east Europe and the Black Sea in spring
(Meltofte 1991, 1993), this may merely point to an underestimation of
the population, however. Wadden Sea numbers decrease during mid and
late May, when first the European sub-arctic breeders and then the
arctic breeders leave for their breeding grounds. (...)
Ming, S. & L. Jianjian
(1992): The dynamics of body composition of overwintering
Dunlin Calidris alpina sakhalina. Wader Study Group Bull. 64: 35-36.
Minton, C.D.T. (1975):
Waders of the Wash - ringing and biometric studies. Rep. Sci. Study
Group of the Wash Water Storage Scheme.
(1985): Bemerkenswerte avifaunistische Beobachtungen aus
Mecklenburg. Orn. Rundbr. Mecklenb. 28: 68-96.
Nieboer, E. (1972):
Preliminary notes on the primary moult in Dunlins Calidris
alpina. Ardea 60: 112-119. A
Dutch pioneer paper, fieldwork at Schiermonnikoog in 1968 and 69, no
(1955): Rylens (Calidris alpina (L.)) traek i Nordeuropa.
DOFT 49: 18 - 49.
(...)No doubt some of the Dunlins observed
in southern Sweden - Norway and in Denmark come from northern
Scandinavia, but studies at Jæren indicate that many of the
birds come from northern Russia and Siberia. The Taymyr peninsula
probably acts as a sort of migratory divide. One bird with bill 38 mm
no doubt comes from Western Siberia.
Mr HOLGER HOLGERSEN tells (in litt.)
that a bird ringed at Jæren on Sept. 22nd, 1950, was
recovered from the Yamal Peninsula in northwestern Siberia in June 1951.
The populations of Russia and Siberia must migrate WSW along
the northern coast of Russia. However, some birds probably go due south
(inland migration has been observed) but they will hardly touch Europe.
At Rossitten there were large birds, too, probably coming from West
Siberia also. These birds must have passed the Onega-Ladoga
lake-district (PALMÉN'S migration route).
The Öland birds may have come from the Estonian
islands of Hiiumaa and Saaremaa as the migration is partly west-bound.
No doubt these birds have come there by the same route as those
migrating along the southern limits of the Baltic.
South-directed birds (transversing the inland of Central
Europe): From Rossitten 33.3 per cent, from Öland 9.3 per cent
and from Amager 5.0 per cent. Birds from Jæren going south
will be led along the western coast of Jutland. Still, one bird was
recovered in Zealand(...).
No strong migration should be expected at Jæren,
but nevertheless it is very strong. Some of the birds cross the North
Sea, but many of them go straight south and are recovered in Denmark
(10.6 per cent). There may be two causes for this, viz.: 1.
North-Scandinavian birds going south cross the migration route of
eastern birds going southwest. 2. There is a regular deviation of the
birds going SW so that they for some reason are pushed northwards. From
Jæren they either continue in the old migration-direction or
they try to find again the old migration route by going S.
It speaks for the second suggestion, that ten birds ringed at
Jæren were recovered at Öland in later years, and
two recorded at Amager. Only one bird ringed at Öland was
recovered at Jæren in a later season.
(1976): Zur Biometrie des Alpenstrandläufers
(Calidris alpina) in den Rieselfeldern Münster. Die Vogelwarte
28: 278 - 293. (Biometry of Dunlins in the Sewage Farms of
1. From 1969 on to 1975
331 Dunlins were caught and measured in the sewage farms of
Münster, 13 of them in the home-migration period. In the
off-migration period only 12 adults were ringed. Therefore this study
mainly deals with juvenile birds.
2. The frequency distribution of wing lengths
corresponds approximately to a normal distribution, in contrast to the
bimodal distribution of bill lengths. According to these measurements
by far the greatest part of the birds caught belongs to the nominate
race, fewer individuals to the race C. alpina schinzii
and very few probably to C. alpina sakhalina
(about 3 cases).
3. The pentade mean values of wing and bill lengths
show a distinct downward trend throughout September and October.
4. The standardized weights yield a normal
distribution; the mean weight is quite high in comparison to dates from
literature. The pentade mean values of weight do not demonstrate clear
changes throughout the off-migration period. The changes of weights of
recaptured Dunlins scatter very much and do not show a trend.
5. Correlations between various measurements are
statistically highly significant.
6. 20 % of juvenile Dunlins were found moulting body
feathers and wing coverts.
Page, G. W. (1974):
Age, sex, molt and migration of Dunlins at Bolinas Lagoon. West. Birds
5: 1 - 12.
Pettersson, J. (1994):
Ottenby fågelstation 1993, in: SOF 1994.
Fågelåret 1993. Stockholm.
Pienkowski, M. W. & W. J.
A. Dick (1975): The migration and wintering of
Dunlin Calidris alpina in north-west Africa. Orn. Scand. 6: 151 - 167.
The numbers of Dunlins present during the
year on the coasts of north-west Africa are summarised. Information on
timing of migration, ringing recoveries, and analysis of bill lengths
is used to determine the geographical origins of these birds. Most
individuals are from the breeding populations in southern Scandinavia,
western Europe, and Iceland, so that Morocco and Mauritania are of
unique importance to these populations in the non-breeding season.
There is some overlap in Morocco with populations from the northern
Eurasian breeding grounds whose main wintering area is further north in
Western Europe. The north-west African birds migrate in short flights
without putting on large fat reserves. Many
birds moult their primary feathers during migration.
Pienkowski, M. W. (1976):
Recurrence of waders on autumn migration at sites in Morocco.
Vogelwarte 28: 293 - 297.
Pienkowski, M. W., Knight, P. J.,
Stanyard, D. J. & F. B. Argyle (1976): The
primary moult of waders on the Atlantic coast of Morocco. Ibis 118: 347
(...)Similar rates of primary feather
replacement relative to specific moult duration were observed in all
species for which information was available. Comparisons between
species and with published studies showed that variations
in rate of moulting between species and between different geographical
populations of the same species were largely due to differences in
feather growth rate rather than in the number of primaries concurrently
in growth. Variations in rate between individuals of the
same population were achieved, at least in the first part of moult, by
differences in feather dropping rate resulting in differences in the
numbers of primaries growing concurrently.
(...)Most Redshank and possibly Dunlin
migrated in active wing moult.
Pienkowski, M. W., Lloyd, C. S.
& C. D. T. Minton (1979): Seasonal and
migrational weight changes in Dunlins. Bird Study 26: 134 - 148.
In eastern England, Dunlin weights peak in
December. Is this because food is abundant then, or an 'insurance'
against cold weather to come? Such early winter weight peaks do not
occur in south-western Britain and the implications of this are
Pienkowski, M. W. & P. R.
Evans (1984): Migratory behaviour of shorebirds in
the western Palearctic, pp. 73 - 123 in: J. Burger & B. L.
Olla: Behavior of Marine Animals. Vol. 6, Shorebirds: Migration and
foraging behavior. Plenum Press, New York.
Piersma T. & N. E. van
Brederode (1990): The estimation of fat reserves in
coastal waders before their departure from Nortwest Africa in spring.
Ardea 78: 221 - 236.
To derive realistic equations for
evaluating the fat loads of waders before their departure from NW
Africa in spring, we have analysed samples of waders inadvertedly
killed during catching operations in Morocco, Tunisia and Mauritania.
We studied the relationships between body and fat mass and structural
size variables. Part of the original variation in body mass was
attributable to a constant relative water loss between capture and
first weighing, and body mass values used in the consequent analyses
were corrected accordingly. In the four species for which large samples
were available (Knot, Little Stint, Dunlin and Redshank), linear
regression of fat mass on body mass indicated that 50 - 60 % of the
differences in individual body mass is due to differences in the total
fat mass. In all four species wing length correlated well with lean
mass, suggesting that this dimension is generally a better structural
variable than total head, bill and tarsus plus toe length. Only in
Dunlins, bill length correlated best with lean mass. Multiple
regressions with fat mass as the dependent variable and body mass and
structural size variables as independent variables, showed that only
those dimensions which correlated with lean mass, contributed
significantly to the explained variance in fat mass in addition to body
mass. An alternative regression model in which body mass was estimated
from fat mass and structural size variables and then reformulated, did
not lead to improved predictive equations. The suggested equations to
estimate fat mass in individual Knots, Little Stints, Dunlins and
Redshanks allows the estimation of fat mass of the heaviest birds with
an accuracy of ca 30 %, but with a much lower accuracy in light birds
(all estimated values within 100 % from the true value).
Pitelka, F. A., Holmes, R. T.
& S. F. Maclean (1974): Ecology and
Evolution of Social Organization in Arctic Sandpipers. Amer. Zool. 14:
185 - 204.
A comparative analysis of sandpiper social
systems on arctic and subarctic breeding grounds (24 species in the
family Scolopacidae, subfamily Calidridinae) shows four major patterns.
In a majority of the species (15), populations are dispersed through a
strongly developed territorial system, with strong monogamous pair
bonds and only minor yearly fluctuations in numbers. The second pattern
isseen in three species in which the female of a pair may lay two sets
of eggs in quick succession, one for each member of the pair to
incubate. This opens opportunities for facultative polygyny or
polyandry ('serial polygamy') and for the evolutionary weakening of the
strong pair bond seen in the first pattern. The third and fourth
patterns are those of polygyny (three species) and promiscuity (three
species). These six species show clumped dispersions; their
year-to-year fluctuations tend to be strong; the males defend
compressible, often small, territories; and high densities can occur
locally. It is suggested that the pattern of overdispersion and
monogamy represents a conservative mode of adapting to high-latitude
environments, while the pattern of clumped dispersion with polygyny or
promiscuity represents an opportunistic mode in that the birds are
concentrated into breeding areas where and when weather, food, and/or
some other environmental factors are particularly favorable. Apparently
falling evolutionarily between these two basic patterns are several
species conservative in their life-styles, but polygamous at least
occasionally and showing some features of opportunism. There is thus a
striking diversity of social systems in calidridine sandpipers, that
is, in the styles of habitat exploitation they have evolved in the
arctic and subarctic habitats to which their breeding is confined. A
graphic model suggesting paths of evolutionary development and of
interplay among factors considered critical in the evolution of these
systems is proposed.
Remisiewicz, M. (1996):
Influence of weather conditions on the autumn migration of Dunlin (Calidris
alpina) at the southern Baltic coast. The Ring 18: 73 - 88.
Roos, G. (1962):
Vinterfåglar på Falsterbonäset. Fauna och
Flora 57: 249 - 273.
Roos, G. (1984):
Flyttning, övervintring och livslängd hos
fåglar ringmärkta vid Falsterbo (1947-1980). Anser,
Supplement 13. Lund 1984.
Ruiz, G. M., Connors, P. G.,
Griffin, S. E. & F. A. Pitelka (1989):
Structure of a wintering Dunlin population. Condor 91: 562 - 570.
(1990): Sind Zugmuster und Rastplatzansiedlung des
Alpenstrandläufers (Calidris alpina alpina) abhängig
vom Alter? J. Orn. 121 - 139. (Are there age dependent differences in
migration patterns and choice of resting sites in Dunlin Calidris
The Dunlin is the most numerous wader
species in the whole Wadden Sea. It uses the area mainly for fattening
in spring and for moulting in late summer. In the Wadden Sea a very
strong site fidelity in adults was found. The same is true in the
British estuaries, which are the main winter quarters. This allows the
adults to develop a good knowledge of local conditions in the
comparatively few areas used. In contrast to the adults, juveniles on
autumn migration stop at more places and stay longer at each. They also
use sites where only a very few adults are seen. Results
of catching and counting in the Wadden Sea suggest that competition
between adults and juveniles influences the dispersion of juveniles.
To explain these phenomena, a hypothesis on migration patterns is
presented. It is suggested that juveniles start their first autumn
migration by taking only a rough general direction without aiming to
reachparticular resting sites. They
probably find these by trial and error, visiting only suitable sites
again in the following years. Therefore juvenile Dunlins
should discover newly arisen sites very quickly and may even fill them
up. They should not stay at those sites which decrease in quality, so
these sites will loose numbers in spite of high site fidelity of
adults. The hypothesis could also help to explain results which are so
far assumed to be caused by the occurrence of different subpopulations.
This is a speculative paper, and I think I see the "epistemological"
elements of its structure: a thought construct reified into reality.
Under normal circumstances this course might be quite legitimate, but
if the justification fails - if only to some extent - the speculator is
in trouble. He must make exceptions, and these exceptions start a
landslide. Rösner's model holds as long as it is not
(1997): Strategien von Zug und Rast des
Alpenstrandläufers (Calidris alpina) im Wattenmeer und auf dem
Ostatlantischen Zugweg. Aachen 1997. (Strategies of staging and
migration of Dunlin in the Wadden Sea and along the East-Atlantic
2. In the Wadden Sea,
Dunlins are the most abundant bird species. Reaching counts of at least
1.2 million, almost all individuals of the West European wintering
population can occur here at the same time. In the Schleswig-Holstein
part of the Wadden Sea (SHW), numbers up to 600,000 were reached.
Compared to other species, Dunlins are spread evenly across the SHW.
They are present year-round, reaching their highest numbers from August
to October and in April/May and very low numbers in June. During normal
winters 10-20 % of the population are present in the SHW, during ice
winters 2-4 %.
3. Among the staging areas, short-term and long-term
can be distinguished. Along the Baltic
coast there are numerous short-term staging areas. The
waves of migration observed correspond well with the seasonal phenology
in the long-term staging area SHW. Ringing recoveries also show that a
large proportion of the SHW Dunlin regularly migrate along the Baltic
4. The coasts of Great Britain and Ireland are the
most important wintering area for SHW Dunlins. The south-western Wadden
Sea, the Rhine Delta and the French and Portuguese Atlantic coast are
also visited. Only a few individuals reach the Mediterranean Flyway
and, possibly, Africa.
5. The breeding origin of SHW Dunlins includes
mainly the tundra areas from northern Scandinavia to the Yamal
Peninsula or just east of it. Birds from Taimyr do not, or only
exceptionally, reach the SHW. A considerable fraction of the small
Baltic breeding population also stages in the SHW. There is no
indication for birds of Nearctic origin. These results were reached
mainly by colour-ringing on the breeding grounds; morphometric and
genetic studies added to the picture.
6. Dunlins are highly site-faithful not only to
breeding areas but also to their natal areas and to staging areas. SHW
birds are, over many years, observed almost exclusively in the same
staging areas; only few also visit other areas within the Wadden Sea.
7. Juveniles leave the breeding area later than
adults and use partially different migration routes and short-term
stopover areas. Even in the long-term
staging area they initially hardly mix with adults and, even months
later, still show a different distribution from that of the adults.
This can be explained mainly by lack of experience, especially
concerning predators. An effective mechanism for displacement of
juveniles by adults could not be found. Proportions of juveniles are
larger in the south-western than in the north-eastern Wadden Sea,
probably because of differences in migration routes.
8. The characteristic features of juvenile migration
hold one key to understanding the migration system and patterns of use
of staging areas in Dunlin. Newly emerging areas can be settled quickly
by juveniles. At the same time, areas with high hunting pressure (such
as, perhaps, France) can act as a sink for juveniles.
9. By combining juvenile data from many short- and
long-term staging areas, an index for the population-wide annual
breeding success since 1948 is created. It shows a weak three-year
cycle and some correlations with the breeding success of other
arctic-breeding bird species. Fluctuations in Dunlin breeding success
are smaller than in other species, probably because of the wide range
and less extreme breeding conditions of Dunlin.
10. For the period since 1970, data from numerous
areas are combined to a 'flyway index' for the western European
wintering population, which numbers from 0.9 to 1.5 million birds.
Periods of stable or increasing population numbers were interrupted by
a ten-year period of low numbers. Unusually high mortality in the
breeding areas in some years, fluctuation in production of young and
ice winters majorly influenced the population development. The general
increase in numbers probably started already before 1970, following
very low population levels due to hunting mortality in the first half
of this century.
11. On a large spatial scale, birds from diferent
breeding areas are separated according to their migration times and
routes. On a smaller scale, e.g. within the Wadden Sea, the characteristics of juvenile migration
largely preclude a spatial separation of birds of different breeding
origin. The temporally separate migration of Baltic birds
is an exception here. The birds of
northern breeding origin mix to a large extent; their
timing of spring migration varies gradually according to the onset of
breeding which varies by about one month across the climatic zones of
the breeding area.
12. Within the range of the species, different life
history strategies can be found. Birds breeding in the Baltic, Great
Britain and Ireland tend to be limited by breeding habitat and have
abundant survival habitat, whereas the opposite is true for birds from
Northern Scandinavia, western and eastern Siberia and northern Alaska.
13. At least in the past, the size of the western
European wintering population was determined by hunting. The limiting
factors at present are less certain, nor is it clear whether the
long-term increase in population numbers is still continuing. On the
West Pacific and Mediterranean Flyway, hunting is probably threatening
populations at present; on the East Atlantic Flyway, primarily the very
small breeding populations are endangered. For the future, an
'integrated population monitoring' of arctic waders is proposed; this
is explained for the example of Dunlin on the East-Atlantic Flyway.
SkOF. Fåglar i
Skåne. Anser, Suppl. (1975-1993): (Annual
Report from Scania).
Smit, C. J. & W. Wolff
(eds.) (1981): Birds of the Wadden Sea. Report 6 of
the Wadden Sea Working Group. Balkema, Rotterdam.
Smit, C. J. & T. Piersma
(1989): Numbers, mid-winter distribution and migration of
wader populations using the East Atlantic Flyway. IWRB Special Publ. 9:
24 - 63.
maximum number of Dunlin recorded on the East Atlantic Flyway, 2.2
million, was stated in this publication.
Smith, K. W., Reed, M. J.
& B. E. Trevis (1999): Nocturnal and
diurnal activity patterns and roosting sites of Green Sandpipers Tringa
ochropus wintering in southern England. Ring. &
Migr. 19: 315 - 322.
A radio telemetric study of Green
Sandpipers at their wintering site, a disused watercress bed in
southern England, shows that they alternate between the watercress bed
and a nearby gravel pit complex over the course of the autumn and
winter. Birds spent most days feeding at the watercress bed and roosted
overnight in the gravel pit complex. During extremely cold weather in
January and February the birds switched to roosting at the watercress
beds. Automatic activity monitoring showed that the
birds were active for around 80 % of each day at all times of year.
Their time active at night varied from around 16 % in autumn to over 40
% in cold conditions in midwinter. The hours the birds were active
during the day and night in mid-winter were inversely proportional to
the maximum daily temperature. The evidence suggests that a low level
of night time activity is normal in Green Sandpipers but the high
levels found during extremely cold winter conditions are the result of
birds attempting to increase their daily food intake thus supporting
the 'supplementary' hypothesis for nocturnal foraging.
SOF. Sveriges fåglar.
(1990): 2:a uppl. Stockholm. (Swedish check-list).
Soikkeli, M. (1966):
On the variation in bill- and wing-length of the Dunlin (Calidris
alpina) in Europe. Bird Study 13: 256-269.
The present study deals with variation in
bill- and wing-length of Dunlin in a population breeding in western
Finland, and also with that appearing in the fairly large material
obtained during migration at the Ottenby Bird Station, Sweden. A new
method is described for distinguishing between males and females by
The population breeding in western Finland belongs to the race schinzii,in
which the mean bill-lengths are 27.8 mm in males and 31.7 mm in
females, and the mean wing-lengths 108.5 and 112.6 mm, respectively.
The material measured during migration at Ottenby consists mostly of
Dunlin of the nominate race, in which the mean bill-lengths are 31.4 mm
in males and 35.2 mm in females.
It is considered very improbable that there should be any
intergradation between alpina and schinzii
in northern Sweden, as claimed by Swedish workers. The Dunlin of the
nominate race breeding in northern Scandinavia may however have shorter
bill- and wing-lengths than other populations of alpina.
CP: I spent some time
studying Fig. 5 of this paper: "correlation of bill-length with
wing-length in the Dunlin population breeding in western Finland".
According to the paper there are 96 male and 71 female bill-lengths, 56
male and 49 female wing-lengths. Plotted in the figure are c96 male and
c65 female bill-lengths - but how were these correlated with
wing-lengths if there were fewer measurements of this kind? There is
something fishy about the skewness of the male component distribution.
Stanley, P. I. & C. D. T.
Minton (1972): The unprecedented westward migration
of Curlew Sandpipers in autumn 1969. Brit. Birds 85: 365 - 380.
The unprecedented influx of juvenile
Curlew Sandpipers Calidris ferruginea in Britain
and Ireland during late August and early September 1969 is analysed
with counts from over 250 localities, these amounting to more than
19,000 bird-days. The principal arrivals took place on 23rd and 26th
August, and at the peak on 31st at least 3,500 were present, over 72 %
of the records coming from the east coast of Britain.(...)An analysis
of all available ringing data indicates a regular autumn migration
route through the Baltic and down the Continental seaboard to Africa,
some taking a more direct line back across the central Mediterranean in
spring. The exceptional influx in 1969 appears to have been due to a
migration unusually far to the west, this being caused by abnormally
persistent cyclonic weather systems centred over the Baltic and north
Russia coinciding with the departure of juvenile Curlew Sandpipers from
their breeding grounds. There is some evidence, too, that in 1969 the
species had had a successful breeding season.
Weight data indicate that the resting migrants were increasing their
weight at up to 7 % per day and calculations suggest that most of them
accumulated sufficient fat reserves in seven to ten days to fly direct
to north Africa; these estimates are compatible with the rapid decline
in total numbers during September. (...)
Stiefel, A. & H. Scheufler
(1989): Der Alpenstrandläufer. Neue
Brehm-Bücherei, nr 592. Wittenberg Lutherstadt: A. Ziemsen
Verlag. A few excerpts from the text quoted here.
Stresemann, E. & V.
(1966): Die Mauser der Vögel. J. f. Orn. 107,
recording "style" in translation, the bird must be a pacifica
since it is moulting on breeding-grounds:
28. Aug. 1880, male, Alaska: St Michael - (followed by registration
number of museum specimen). P 1 to 8 new, 9 g 3/4, 10 g 1/2 -- Almost
fresh winter plumage, only a few black feathers left on belly.
Summers, R. W., R. L. Swann
& M. Nicoll (1983): The effects of methods
on estimates of primary moult duration in the Redshank Tringa
totanus. Bird Study 30: 149 - 156.
The duration of primary moult of Redshank
was estimated from various methods involving drawing straight and
curved lines through a scattergram of points. Estimates ranged from 72
to 109 days. The growth of the
primaries was not constant, so linear regression analysis did not fit
the best line to the data, even when the curving effect of describing
moult in terms of moult scores was corrected for. Linear regression
analyses also gave unrealistically early values for the start and
completion of moult. More satisfactory methods involved drawing a
curved line through the mean dates for each moult score, or each 5 % of
feather mass grown. An even spread of records (nonmoulting
plus moulting birds) through the moulting season is essential to give a
good estimate of duration.
Swann, R. L. & B.
Etheridge (1996): Movements of waders to and from
the Moray Firth. Ring. & Migr. 17: 111 - 121.
Tomkovich, P. & L. Serra
(1999): Morphometrics and Prediction of Breeding Origin in
some Holarctic Waders. Ardea 87: 289 - 300.
Tomkovich P.S., E. G. Lappo
& E. E. Syroechkovski Jr (2000): Ringing
and migratory links of Taimyr waders. Heritage of the Russian Arctic.
Research, Conservation and International Co-Operation. Proc. of the
Int. Sc. Willem Barents Memorial Arctic Conservation Symposium held in
Moscow, 10-14.3.93: 458 - 474.
Ringing of waders in the Taimyr Autonomous
Okrug (district), Northern Siberia, dates back to the 1960's. In
1989-1996, a total of 5,700 waders of 24 species were ringed and some
were additionally colour-marked as one of the activities of the
International Arctic Expedition organised by the Institute of Ecology
and Evolution, Russian Academy of Sciences. Forty-six recoveries of 11
species have so far been obtained including 15 birds marked on the
Taimyr Peninsula and 31 ones ringed elsewhere. The highest recovery
rate was that in marked Red Knots (Calidris canutus). Indeed, 2.6 % of
the 312 birds ringed at the breeding grounds were recovered during the
study. Marking Little Stints (Calidris minuta) turned out to be least
efficient, no recovery having been obtained despite the most extensive
ringing of these birds (over 1,700 individuals). Curlew Sandpipers
(Calidris ferruginea) breeding on the Taimyr Peninsula were shown to
have the broadest winter distribution range which encompasses western
and south-eastern Europe, South Africa, the Indian subcontinent and
Australia. It is concluded that the geographic position of Taimyr in
the centre of northern Siberia, its wide and diverse expanses of open
marshy habitats, and geological history of the peninsula are
collectively responsible for its paramount importance for the
reproduction of many wader species using different migratory routes.
Underhill, L. G. & A.
Joubert (1995) Relative masses of primary feathers
feathers. Ring. & Migr. 16: 109 - 116.
A knowledge of the relative masses of the
primary feathers is necessary to compute the percentage of feather mass
grown by a bird moulting its primaries, as a step towards estimating
the parameters of moult using the Underhill-Zucchini moult model. Also,
wing shape characteristics can be described by fitting a polynomial
regression model to the relative feather masses. This paper presents
relative feather mass data for 38 species, primarily southern African.
Further data are required to evaluate the concept of fitting
mathematical models to describe wing shape.
Wenink, P. W. (1994)
Mitochondrial DNA sequence evolution in shorebird populations.
Dissertation. Wageningen 1994.
A few excerpts from the summary
(references excluded):"(...)There are several reasons why mtDNA is the
molecule of choice to probe the recent evolutionary history of a
species. Most importantly, mtDNA accumulates substitutions at a high
average rate that permits the tracing of genealogies within the time
frame of speciation. The population structure of shorebirds, like that
of arctic-breeding waterfowl, must have been influenced dramatically by
the Pleistocene glaciations (mainly during the last one million years).
The fastest evolving part of the mtDNA genome, the non-coding control
region, offers sufficient genetic resolution to reveal differentiation
of such recent origin. The typical mode of maternal inheritance, the
absence of recombination, end the presumed neutrality of substitutions,
are characteristics that add to the suitability of mtDNA for the
construction of robust phylogenies.
(...)The dunlin, on the other hand, became divided into several
isolated populations during the Pleistocene and has
retained a significant amount of intraspecific genetic diversity until
(...)A genealogical tre relating (35 different genotypes) revealed five
major clusters. Each cluster has high geographic specificity. The
cluster containing the most divergent sequences is present along the
Atlantic coast of North America and represents the dunlin population
breeding in arctic central Canada. Two clusters of genotypes are
located principally in western Europe and central Siberia. Evidence for
a low level of gene flow between these latter two populations was
provided by three individuals whose genotypes suggested they were
immigrants. Two other clusters are found along the Pacific coast of
A plausible scenario for the genetic divergence of the major dunlin
lineages is the ancestral fragmentation of populations over tundra
refugia, that were created by the extensive glaciations of the northern
hemisphere during the Pleistocene. Prolonged isolation of populations
of reduced size increased the effect of genetical drift and this may
have led to the observed mtDNA monophyly. The different lineages
continuously diverged by the process of mutation. This ancient
subdivision has been retained after retreat of the icesheets, most
likely as a result of the strong
site-fidelity of dunlins to their breeding ground. [CP: Fidelity to wintering
grounds and maybe equally to resting and staging
grounds not included here!] Dunlin populations
could thus not become homogenized genetically because gene flow is not
extensive enough between them.
(...)Phylogeographic groups can be correlated to the global geography
of morphometrically defined subspecies in the dunlin. Whereas several
disputed subspecies gain support from the genetic data (i.e. C.
a. hudsonia in central Canada and C. a. centralis
in central Siberia), other subspecies merge into the same
phylogeographic group. No major phylogenetic divisions are apparent
among the morphometrically dissimilar populations in north-eastern
Greenland, Iceland, the Baltic Sea, and Norway (recognized until now as
three to four different subspecies). Gauged by the depth of the other
phylogenetic splits in dunlin, they can jointly be referred to as C.
It is thus revealed how
morphology lacks an evolutionary perspective in the determination of
intraspecific taxonomy. (My emphasis; CP) For the dunlin, a
parallel morphological evolution of genetically divergent populations,
as well as the opposing process of morphological divergence of
evolutionary closely related populations, is observed. Morphometric
characters employed in intraspecific avian taxonomy are suffering from
homoplasy, either as a result of character plasticity and environmental
induction, or because of very high mutation rates and strong directive
selection acting on phenotypes. Because morphometrically different
dunlin populations are often mixed outside the short breeding season,
environmental induction of morphology seems unlikely, although this
possibility remains to be investigated."
CP:This boils down to two
alternatives: genetically defined "haplotypes" (the individual maybe
breeding in the main area of another haplotype) and morphologically
more or less well-defined "population groups". In the field we can only
discern the latter groups, and the aim of the field-worker must be to
obtain maximum morphological differentiation, using
all characters available. It seems to me, Dunlin are not very "mixed"
outside the breeding season - they know their kin, always know their
kin and seek it.
Wenink, P. W. & A. J.
Baker (1994): Mitochondrial DNA lineages in
composite flocks of migratory and wintering Dunlins (Calidris alpina),
in: Wenink 1994 (above).
Witherby, H. F. et al.
(1958) in: The Handbook of British Birds. Vol. IV. London: H.
F. & G. Witherby Ltd. A short remark by H. F. Witherby quoted.
"Dr C. B. Ticehurst mentioned two large
birds taken in Fair Is. on Sept. 23, 1905, which he considered to be C.
a. sakhalina. I have examied these: female wing 116, bill
40, male wing 119, bill 35. The bills are certainly very large, but the
wing of the female is short for sakhalina, and in
both birds there is only slight edging
of white on the outer webs of the inner primaries instead of the white
extending to the rhachis as is usual in sakhalina.
Among other large British-taken birds, I have examined only three with
a considerable amount of white on the outer webs of the inner primaries
(...) In the last the white just reaches the rhachis and in the other
two not quite. These may be referable to C. a. sakhalina,
but before admitting that race to the list I think we should have more
definite evidence, as very occasionally examples of C. a.
alpina have an unusual amount of white on inner primaries."
This is history, passed by recent genetical research. I just want the
quotation here as a morphological reference.
Wymenga, E., Engelmoor, M., Smit,
C. J. & T. M. Van Spanje (1990):
Geographical breeding origin and migration of waders wintering in West
Africa. Ardea 78: 83 - 112.
This paper discusses the geographical
breeding origin and migration routes of 3.5 million waders using the
Banc d'Arguin, Mauritania and Guinea-Bissau, based upon morphometrical
data and supplementary ringing recoveries. For several species our
analyses confirm earlier findings on breeding areas and migration
routes. For at least part of the Ringed and Grey Plovers, Redshanks,
and to a lesser extent also Bar-tailed Godwits, Whimbrels, Curlews and
Turnstones, there are indications that birds wintering in Guinea-Bissau
originate from breeding areas further north and east, as compared to
birds wintering in Mauritania. The morphological characteristics and
measurements do not allow the determination of the exact location of
the breeding areas. This is due to clinal gradients in measurements, as
a result of which there is much overlap in sizes. During spring
migration most wader species wintering in W. African coastal wetlands
travel via a route following the W. African and W. European coastline.
Little Stint, Curlew Sandpiper and Curlew are exceptions to this rule.
There are indications that at least part of these birds migrate through
NW Africa, the Mediterranean and the Black Sea area.
Zajac, R. (1980):
Different autumn migration rates of sexes in the Dunlin Calidris a.
alpina, as determined by means of normal probability paper. Acta orn.
17: 107 - 118.
Zwarts, L., B. J. Ens, M. Kersten
& T. Piersma (1990): Moult, mass and flight
range of waders ready to take off for long-distance migrations. Ardea
78: 339 - 364.
Wader species wintering on the Banc
d'Arguin increased their body mass by about 40 % during the 4 - 6 weeks
before their departure in spring. This estimate is based on 1) the
empirical fact that most waders which had finished or suspended their
body moult into summer plumage were heavy and thus ready to take off,
and 2) the assumption that only the heaviest birds in the population
left, which allowed the mass of disappearing waders to be estimated
from counts and the frequency distribution of body masses in samples of
captured birds. The mass gain on the Banc d'Arguin is just over 1 % per
day, when expressed as a proportion of winter mass. A review of studies
on waders preparing for migration shows that 1) the total migratory
reserve adds 20-80 % to winter mass, 2) the rate of mass gain is 0.1-4
% per day and 3) the period of mass increase lasts four weeks on
average, but longer if waders prepare for spring migration on the
wintering areas. We suggest that all wader species leaving the Banc
d'Arguin at the end of April and the beginning of May are able to reach
SE and NW Europe without refuelling. This seems only possible if
current equations to predict flight range systematically underestimate
this range, even when the energetic benefits of favourable winds at
high altitude are taken into account.
To "Studies of migrating Dunlin Calidris
alpina in the Sound area, S. Sweden: Introduction"
To "Phenology and biometry of Dunlin Calidris
alpina migrating by way of the Sound area, S. Sweden"
To "Migrating Dunlin Calidris alpina
in the Baltic area: the moult issue"
To "Wintering and spring staging Dunlin Calidris
alpina in the south Baltic area"
To "Migratory progress of juvenile and adult
Dunlin Calidris alpina from two perspectives: the
Baltic and the Waddensea"
To "Bill-length distributions in Dunlin Calidris
To the bill length account
About "adult buff" coverts
To the Meissner scale
Last addition (133 entries) 6.2.06, links changed 1.6.04.