Yellow Wagtail papers:

references, abstracts and comments. Where there is no abstract, an abstract has been written, where abstracts are too long they have been abridged. Abstracts in languages other than English have been translated into English. Trends or booms of interest can be connected with most species; many papers in this list are outright antiques, and I have a feeling that the Yellow Wagtail is out of the focus of attention right now. After-1990 publications concern mainly observations of out-of-place individuals, a perversion characteristic of our recent period. The comment is personal, it points out errors and possible follow-ups, it is begun: CP:

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

Ash, J. S. (1969): Spring weights of trans-Saharan migrants in Morocco. Ibis 111: 1-10.

Some aspects of the weights of over 5,500 birds of 79 species, mostly migrants, captured in spring at an oasis on the northern edge of the Sahara, are discussed. Mean weights for five species were 26-44 % below those of fat birds (those containing at least 30 % lipid) weighed about the same time on the south side of the desert. Weights of fresh arrivals in Britain are higher than those in North Africa, but the differences are not great, suggesting that these have also made a long journey across Europe. Peak arrival times of day-migrants differed from those of night-migrants and the weights of some species varied with the time of day. There was no great advantage to migrants in remaining at the oasis; there were few weight changes greater than those normally occurring within an individual's daily range. Several species lost weight steadily during a cold spell, and many died. Male Swallows are heavier and larger than females, and in both sexes weight increases with wing-length.

Aymí, R. & J. Jaume. (1992): Muda interrompuda en una Cuereta groga Motacilla flava. Butll. GCA 9: 11 - 12.

During a ringing campaign of Yellow Wagtails, 2438 individuals were handled at the Ebro Delta (NE Spain) in September 1992. On 27th September 1992 an adult Yellow Wagtail with interrupted moult was trapped. The bird had renewed all its plumage during the postnuptial moult, with the exception of the two innermost secondaries, two to six feathers in the median and less coverts of each wing and the smaller feather of the alula in the right wing. This is the first record of interrupted moult in the species.


Brennecke, H.-E. (1949): Zur Frage des zweimaligen Brütens der Schafstelze (Motacilla flava flava). Vogelwelt 70: 149.

Bub, H. (1981): Stelzen, Pieper und Würger. Kennzeichen und Mauser europäischer Singvögel. Die Neue Brehm-Bücherei 545, Ziemsen, Wittenberg Lutherstadt.


Crousaz, G. de. (1961): La migration d'automne des Motacillidés aux cols de Cou-Bretolet. Nos Oiseaux 26: 78-104.

Curry-Lindahl, K. (1958): Internal timer and spring migration in an equatorial migrant, the Yellow Wagtail (Motacilla flava). Ark. f. Zool., ser. 2, band 11, nr 33.

Curry-Lindahl, K. (1963): Molt, body weights, gonadal development and migration in Motacilla flava. Int. Orn. Congr. Ithaca 13: 960-973.

Different subspecies of the Yellow Wagtail leave the wintering grounds in tropical Africa in a certain order and without any relation to changes in local weather conditions. The first to leave in spring is the southerly race M. f. feldegg, members of M. f. lutea are next to take off, followed by M. f. flava and M. f. flavissima, while the last to leave its winter quarters is the northernmost M. f. thunbergi.
Physiological phenomena, molt, fat deposition, and gonadal development as well as departures on migration in these races (populations) of M. flava follow different patterns, in spite of the fact that the birds are wintering together in uniform external conditions.
The normal sequence of physiological events while the Yellow Wagtails are to be found in tropical Africa is approximately as follows. Molt occurs in December - April, fat deposition in January - April, gonadal growth in February - May, and spring migration also in February - May. The molt may be terminated before or after migration, while deposition of fat and initiation of growth of gonads precede the vernal flight. Prior to the onset of spring migration, the swelling gonads are still small and only slightly advanced beyond the condition that is found during the previous months. Arrival at the breeding areas occurs for different races in March - June. In M. f. flava and M. f. thunbergi the gonads increase tremendously in size during the migratory flight. Reproduction can generally start immediately after the arrival of these races at their breeding grounds.
The wide scale of temporal range in the initiation and further development of gonadal growth, with all its reproductive processes, as well as of molt and fat deposition, indicates that each subspecies depends on different internal, rhythmical factors. These may be linked with external stimuli to which the birds are exposed when they are in their breeding range, or they may involve an internal timer, which is entirely innate from the very beginning of the birds' life, thus also in this case synchronized to the conditions at the breeding grounds.

Czikeli, H & G. Knötzsch (1979): Rufunterschiede zwischen südlichen und mittel- bis nordeuropäischen Rassen der Schafstelze Motacilla flava ssp. Ökologie Vögel 1: 159-163.


van Dijk, J. (1958): De Engelse Gele Kwikstaart als broedvogel in Nederland. Limosa 48: 86-99.

Dittberner, H. & W. (1981): Die Englische Schafstelze (Motacilla flava flavissima [Blyth]) in der DDR. Beitr. Vogelk. 27: 230-231.

Dittberner, H. & W. (1984): Die Schafstelze. Neue Brehm-Bücherei 559, Ziemsen, Wittenberg Lutherstadt.

Drost, R. (1948): Populationsstudien an der Englischen Schafstelze Motacilla flava flavissima Blyth auf Helgoland. Vogelwarte 15: 18-28.


Fry, C. H., J. S. Ash & I. J. Ferguson-Lees (1970): Spring weights of some Palaearctic migrants at Lake Chad. Ibis 112: 58-82.

A visit was made to Malamfatori, on the western shore of Lake Chad, Nigeria, from 22 March to 13 April 1967, with the principal aim of studying Palaearctic migrants in relation to the environment. About 2,400 Palaearctic migrants of 29 species were mist-netted in beds of bulrush Typha australis and thickets of saltbush Salvadora persica. (...)
Yellow Wagtails Motacilla flava, Sedge Warblers Acrocephalus schoenobaenus and Whitethroats Sylvia communis were abundant and were studied in greater detail than other species. Yellow Wagtails fed almost exclusively on midges, particularly the abundant Tanytarsus spadiceonotatus. Sedge Warblers fed on small insects and spiders, and Whitethroats on Salvadora fruits. Sedge Warblers and some other chiefly insectivorous species turned to a diet including berries shortly before emigrating. (...)
Yellow Wagtails, Sedge Warblers and Whitethroats deposited up to 40 % fat/live weight; Sand Martins Riparia riparia had up to 28 %, and a small sample of Ruffs Philomachus pugnax up to 17 %. In the case of Sedge Warblers, fat reserves were sufficient for crossing the Sahara both to the north and to the northeast.
Contrary to the findings in some previous lipid studies, the fat-free dry weight and water content increased during fattening. The fat-free dry weight increase was about 34 % in Yellow Wagtails, 18 % in Sedge Warblers, and 35 % in Whitethroats. The tissues involved in this increase were not investigated, but a study of Yellow Wagtails at Malamfatori in 1968 (in prep.) suggests that the pectoral muscles hypertrophy during fat deposition sufficiently to account for nearly all of the increase in fat-free dry weight and water fraction.

Fry, C. H., I. J. Ferguson-Lees & R. J. Dowsett. (1972): Flight muscle hypertrophy and ecophysiological variation of Yellow wagtail Motacilla flava races at Lake Chad. J. Zool.: 293-306.

During the few days before emigration to the Palaearctic, the weight of Yellow wagtails wintering in Africa doubles. Most of the increase is due to the deposition of fat, as is well known, but a part of it is shown to result from hypertrophy of the pectoral muscles. The same applies to other Palaearctic birds, four warblers and a hirundine, that winter in Africa.
Eleven subspecies of M. f. flava occur at Lake Chad in spring. The four black-headed ones have more restricted habitat requirements than some of the others; however, no differences in diet have been found. There is no evidence of hyperphagia and little of diet change when fattening. Broadly, the races that have farthest to migrate leave earliest, and their sexual recrudescence and fattening are early.
Yellow wagtails wintering at or passing through Lake Chad breed mainly in eastern Europe (from the Adriatic to the Gulf of Finland, between about 12° and 30°E). They probably migrate on a great circle route, and during the flight lose one gram of weight, mainly fat, per 200 km.


Gatter, W. (1987): Transl.: Bird migration in West Africa: Observations and hypotheses on migration strategies and migration routes. Bird migration in Liberia, Part II. Die Vogelwarte 34: 80-92.

Observations on the movements of Palaearctic migrants in Liberia during six winters are revealed. Various migration patterns which can be interpreted with reference to meteorological factors (wet season, harmattan), are presented in detail in GATTER 1987 (first part of this paper; Verh. orn. Ges. Bayern). All over the whole of Liberia and the Atlantic, the average direction of migration runs parallel to the Liberian coast, in both autum and winter at 130°, and in spring at 300°. It is assumed that a heavily used, broad front migration occurs which converges over the Iberian peninsula, and then follows the curve of the West African subcontinent over the Atlantic and the Mahgreb. Thereafter it changes course to the south-east and pours into the Sahel and Sudanese savanna. From November until at least January, another south-east movement occurs, which is induced (food shortage, aridity) and supported (tail winds) by the north-east trade wind or harmattan. Part of the population continues migration to the equatorial region and probably even further south.
Spring migration in Liberia is more intense for many species. The reason for this is seen in a westerly migration along a more southerly latitude than in autumn. (Loop migration along the line of latitude).
By way of example the hypothetic loop migration of Motacilla flava thunbergi through the West African subcontinent is discussed.
Westerly spring passage along the Guinea Gulf Coast allows for the exploitation of an otherwise unused ecological potential following the departure of the wintering populations. The wet areas of the Upper Guinea region are thus available as an ecological niche for late migrating species.
Westerly migration means that those populations reach the southern edge of the Sahara later, when rain is spreading northwards; and have a point of departure in the far west, and can thus take advantage of two favourable positions for a Sahara-crossing: A) northerly migration towards the Iberian peninsula follows the line of the meteorologically favourable Atlantic coast; B) their northward migration starts from a point of departure in the west; then depending on the birds destination, they leave the coastal strip at various latitudes with SW-NE tail winds.(...)

Géroudet, P. (1946): Le passage de Bergeronnettes printanières du Nord de l'Europe Motacilla flava thunbergi Billb. 1818. Nos Oiseaux 18: 202-205.

Haukioja, E. & P. Kalinainen (1972): Transl.: The ecology of some passerines during the moulting period. Porin Lintutiet. Yhd. Vuosik. (Yearbook of Porin Orn. Soc.) 3: 5-16.

Some analyses of moulting data collected during the summers of 1968 and 1969 in the delta of the Koskemäki River (61° 30' N, 21° 30' E), in western Finland, are presented.(...) According to a regression equation the postnuptial moult of the Yellow Wagtail (Motacilla flava) lasts about 40 days, which, if anything, is too long an estimate.(..)
Factors affecting on the timing of the moult are discussed. If we accept the idea that temperate zone passerines reproduce as fast as they can, the following course of events is probable. Breeding lasts as long as the numbers of parents lost before the following breeding season due to the attempt to breed are lower than the numbers of young which reach maturity. In the course of the summer the risk of losses rapidly increases because the clutch size is smaller and thus even the potential breding result is lower. Besides, losses of nestlings are generally higher in late broods than in early ones and, after independence, the young from late broods probably survive less well than those from early broods. Taking into account that parents have less time for late summer events (moult, premigratory fat-deposition), the later they try to breed, then also their losses are probably larger and breeding has to come to a stop rather early. Moulting is the following phase in many passerines.(...)
Some possibilities of moult study as a part of an ecological study are discussed. For example, the importance of the moulting period in the timing of breeding and other cycles is stressed. The cessation of breeding is determined to a large degree by the need to moult at a favourable time. The shortage of available food for nestlings is probably also important but the paramount importance of a favourable time for moulting is shown by the fact that some passerines moulting after autumn migration are capable of laying two clutches per season in spite of late arrival (In Finland e.g. the Reed Warbler, Acrocephalus scirpaceus and probably the Grasshopper Warbler Locustella naevia). Besides this group the only passerines laying two clutches per season in Northern Europe seem to be those capable of postponing their moult and migration to late summer or autumn (and probably are often capable of moulting using vegetable food). Species moulting before migration and eating animal food normally only breed once, evidently because the favourable time before autumn migration is too short for another brood and moult.

CP: The mid section brought out with red is not quite to the point, when it comes to the Scanian breeding population of Motacilla f. flava; this population has a tendency to "push" breeding and ignore moult, and there may be something of a deviating moral here. The question is: is this particular Darwinist approach - or part of it - refuted by the Scanian example, or do Scanian flava merely bring out the imperative environmental constraints in full relief? H. & K. were inspired by Cody, M. L. (1966): A general theory of clutch size. Evolution 20: 174 - 184, but most likely by a few general works as well; there is a taste of David Lack to the whole approach.

Hereward, A.C. (1979): The Autumn Moult of the Yellow Wagtail. Ringing and Migration 2: 113 - 117.

The Yellow Wagtail Motacilla flava flavissima undergoes a rapid complete post-nuptial moult in Britain. Duration of primary moult is 43-45 days and the mean starting date is 19 July. Tail moult is variable in its pattern. The extent of the post-juvenile moult of greater coverts varies by season and between years. The most peculiar feature of moulting Yellow Wagtails is that they seem to start migrating before completing moult.

Herroelen, P. (1967): Determination de l'age, du sexe et des races geographiques de la bergeronnette printanière (Motacilla flava). Bull. Bagueur 3: 26-35.


Johansen, H (1946): De Gule Vipstjerters Systematik og Udbredelse. DOFT 40: 121-142.

The taxonomy of the Yellow Wagtail (Motacilla flava L.) is of great principal interest, as several different subspecies are found breeding together in some areas in southeast Europe and in Siberia. (...)
In this paper the variation of the characteristics are analysed, especially the colour of the head is of principal importance in the segregation of the subspecies. The crown, lores, ear-coverts and eye-stripe of each specimen were examined, both in their geographical and individual variation which is very great. Also the colour shades of the upper and under parts were studied. Then follow the plastic characteristics: length of wing, tail and hind claw. The variation of the wing length is not great (however varying from 72 mm to 90 mm), but it is of fairly great importance in the segregation of closely related subspecies. (...) The hind claw is of importance to the division into groups of the wagtails; it appears that the Asiatic forms have a larger hind claw than the European. (...)
In another chapter the question of the systematic categories which may be applied to the Yellow Wagtails is discussed. There are three views: The Russians, e.g. SUSHKIN (1925), IVANOV (1935) and also DOMANJEVSKI (1925), regarded the yellow-headed forms, at any rate lutea and taivana, and the black-headed ones, as distinct species. However, HARTERT, STEINBACHER and many others only considered them as subspecies. The argumentation as far as the Asiatic yellow-headed forms were concerned was however not sufficient. STRESEMANN (1926) and later on GROTE (1937) found an explanation in regarding them as mutants, so to speak prospective subspecies.
The present author does not consider this necessary and unites the three groups (the yellow-headed, black-headed and grey-headed) in a "species group", (...)
Finally a hypothesis of the development and distribution of the Yellow Wagtails is set forth. The yellow-headed forms: flavissima, lutea and taivana are regarded as survivors of a primitive form which in the past inhabited nearly all the palaearctic region. The isolation of these three forms is very old, and each of them developed dark-headed groups which spread in the interglacial and postglacial periods.
(...)The West-Asiatic group with the primitive form lutea developed the black-headed feldegg-forms. The East-Asiatic group with the primitive form taivana developed, besides the East-Siberian forms, also thunbergi in North Europe.
In the European group comprising the primitive form flavissima a division into two parts occured during the glacial epoch. From the Southwest-European diluvial refuge cinereocapilla (with iberiae and pygmaea) developed, while flava and beema developed from the Southeast European area. the latter invaded, towards the east, the area of the old lutea. Although many hybrids occur, no complete mixing took place, since the subspecies originate from genetically very different groups. Further, beema reached right to Mongolia where, owing to elimination of alleles (= different genes occupying the same relative position in corresponding chromosomes) it developed the very light almost white subspecies leucocephala. The best sign of the European origin of leucocephala is its very short hind-claw.
M. f. dombrowskii is regarded as a hybrid race between the feldegg and the flava group.


Kinzerbach, A. (1967): Zum Vorkommen von Motacilla flava cinereocapilla Savi in Mitteleuropa. J. Orn. 108: 65-70.

(In translation from German): The paper surveys the status of the Motacilla flava cinereocapilla regularly observed in the Alp region of Central Europe. These birds have formed local settlements along the northern edge of the Alps and upper Rhine, loosely connected with the Italian population and by way of hybrid populations in Switzerland with the south French breeding area. The areas mentioned should be regarded as zones of mixture between flava birds and a small proportion of cinereocapilla. So far advances in northerly direction have reached 50° N.

Klementsson, A. (1946): De svenska gulärlerasernas utbredning. Vår Fågelvärld 5: 80-83.

Kraus, M. & W. Krauss (1972): Zum Vorkommen der Englischen Schafstelze (Motacilla flava flavissima) im deutschen Binnenland, mit neuen Nachweisen für Bayern. Vogelwelt 93: 101-106.


Leisler, B. (1968): Probleme der Maskenstelzen-Ausbreitung nach Mitteleuropa. Egretta 11: 6-15.


Marshall, A. J. & J. G. Williams (1959): Pre-nuptial migration of Yellow Wagtail from latitude 0.04 N. Proc. Zool. Soc. London 132: 313-320.

Mayaud, N. (1952): Motacilla flava L. en France, ses races, leur distribution géographique et leurs migrations. Alauda 20: 1-20.

Four races of Motacilla flava are found breeding in France: flavissima along the Channel's coast (including Alderney), from the Somme to the western tip of Brittany (Finistère); iberiae near saint-Jean-de-Luz and in Corsica (1927); iberiae> < cinereocapilla along the Mediterranean coast from the Pyrenees to Marseilles; cinereocapilla near Basel; flava, on suitable places, in the remaining districts of France. Migrating flavissima are especially numerous along the Atlantic coast line. Migrating flava are recorded everywhere in the country and numerous in the South-West. Thunbergi was noted in spring (May) in the eastern half. Records of feldegg are very scarce.

Mayr, E. (1956): The interpretation of variation among the Yellow Wagtails. Brit. Birds 49: 115-119. No summary.

(from the text) With all these questions and doubts it might seem as if the taxonomy and the biogeographic history of the Motacilla flava complex were a complete mystery. This is by no means the case. It is now quite clearly established that the Yellow Wagtail must have gone through a period during which the species was compressed into many relic areas consisting of widely separated populations. During this period the striking differences evolved which now characterize the populations of the species. How long ago this period was, whether during the height of glaciation or during a drought period in the late Pliocene, or during an arid period in one of the inter-glacials is yet to be determined. This much is certain, however, that complete reproductive isolation was not acquired during this isolation, although perhaps partial reproductive isolation between some of the yellow-headed populations and some of the others. Much in the pattern of variation indicates that there is some reproductive isolation also between some of the black-headed and grey-headed forms. In other areas there was so little incipient isolation that it broke down quickly on contact and led to zones of secondary intergradation, characterized by high variability. The basic pattern is clear, but much of the detail will have to be filled in through the study of breeding populations. The analysis of museum specimens, taken on migration and in the winter-quarters, is not likely to add much to what we already know.

Merikallio, E. (1958): Finnish birds: their distribution and numbers. Soc. pro Fauna et Flora Fennica, Fauna Fennica, 5.

Mester, H. (1959): Bemerkungen zum Zug der Schafstelze (Motacilla flava L.). Orn. Mitt. 11: 153-156.

Moreau, R. E. (1972): The Palaearctic-African Bird Migration Systems. Academic Press, London & New York.


Owen, D. F. (1969): The migration of the Yellow Wagtail from the equator. Ardea 57: 77-85.

1. CURRY-LINDAHL and MARSHALL & WILLIAMS have postulated that the departure of the Yellow Wagtail from its equatorial wintering grounds in Africa is determined by either an innate internal timer or by conditions on the breeding grounds during the previous year, or by both. They argue that there are no environmental factors in Africa that could stimulate departure. MARSHALL & WILLIAMS specifically rule out fluctuations in insect numbers as a possible stimulus.
2. But insect numbers do fluctuate near the equator. At Kampala, Uganda, the major fluctuations occur in February-April, the period when Yellow Wagtails are preparing to depart from the wintering grounds.
3. It is suggested that fluctuations in insect numbers acting as an environmental trigger provide a better hypothesis than the existence of an internal timer to explain the departure of the Yellow Wagtail from the equator.


Paulsen, B. E. (1978): Engelsk gulerle, Motacilla flava flavissima. Litt om karakterer i felt og norske hekkefunn. Vår Fuglefauna 1: 81-87.

Yellow Wagtail, Motacilla flava flavissima, breeding in southern Norway. A new breeding locality of this subspecies is described, Sokndal in Rogaland County, where about 12 pairs are supposed to breed. The preferred biotopes are tufted meadows and cultivated pastures, always near water and wetland areas where the birds seek their food. The other breeding localities in Norway are known: Jæren and Lista, all at the South-Western Coast. The total Norwegian population is supposed to be less than 50 breeding pairs.

Pearson, D. J. & G. C. Backhurst (1973): The head plumage of eastern yellow-headed Wagtails wintering in Nairobi, Kenya. Ibis 115: 589-591.

Pennycuick, C. J. (1969): The mechanics of bird migration. Ibis 111: 525-556.

Pennycuick, C. J. (1975): Mechanics of flight. In: Farner, D. S. & J. R. King (eds.) Avian Biology, vol. V. Academic Press, London & New York.


Rendahl, H. (1967): Verbreitung und Zugverhältnisse der schwedischen Schafstelzen. Ark. Zool., Ser. 2, 20: 381-408. No summary.

A very useful and comprehensive paper, that has aged like good wine. [CP]

381 - 388: Description of occurring Fennoscandic Yellow Wagtail subspecies, discussed in connection with the papers of Johansen 1946, Merikallio 1956, Sammalisto 1958, 1961, Williamson 1955.

389-394: Distribution in Sweden, each province treated separately.
395-403: Arrival time in Sweden, a lot of data from an extensive phenology scheme, organized bu the Swedish Museum of Natural History.
403-405: Migration from Sweden; results from the same phenology scheme.
405-408: Results of Scandinavian ringings of Yellow Wagtails. This section is the only one that feels a little antiquated.


Sammalisto, L. (1958): Interracial hybridization as an adaptation mechanism in the Fennoscandian Yellow Wagtail (Motacilla flava L.) population. Ann. Acad. Sci. Fenn. A IV: 41, 1-46.

The role played by natural hybridization in the evolution of animals is still very poorly studied, but lately some cases of interracial hybridization are reported in the ornithological literature. Theoretically, the hybridization is a two-edged evolutionary mechanism: the increase in variability which folows hybridization should create chances for occupation of new habitats, but there is a danger that the breakdown of 'harmonious genotypes' does not result in a new balanced gene combination.
It is supposed by recent authors that the remarkable variation among the yellow wagtails is to a great deal explained by secondary intergradation. 'Migrational drift' also seems to have arole to play, but the oldest theory on 'parallel' mutations seems not to inspire confidence.
One area of secondary intergradation comprises a large part of Fennoscandia, where the eastern race thunbergi and the southwestern nominate race meet. Pairing seems to occur between the races at random, and hence the hybridization has resulted in the establishment of a strong intermediary population in South Finland. The intermediary males are adaptively clearly superior to the parental forms, particularly on treeless bogs and marshes. On the contrary, the intermediary females seem to be adaptively approximately equal to the parent races. A sex-linked heterosis seems to be involved. The adaptive superiority of the intermediary malesis supposed to be based on an ability of the fledglings to survive in the arctic microclimate of treeless bogs.
From South Finland, the intermediary males have spread northwards and occupied the treeless bogs and birch woods of North Fennoscandia. On pine peat-bogs and mountains, the intermediary form has not been able to replace thunbergi, and the male population of North Fennoscandia is thus racially heterogeneous. As a consequence of the fact that the intermediary females are not superior to the parental forms even in South Finland, they have not gained foothold in North Fennoscandia, and the population there is racially homogeneous. In compensation for this, the females seem to be able to more sudden reactions in response to temporary changes in environmental conditions than the males.
All aberrant forms of yellow wagtails observed in Finland are of eastern origin, which fits in well with the migrational drift theory. The proportion of migrational vagrants in the Fennoscandian population as well as elsewhere is so small that the phenomenon must be considered as insignificant in so far as the evolution within the yellow wagtail complex is concerned.
The hybridization of flava and thunbergi has produced variants practically inseparable from nine of the thirteen commonly recognized races of the greyheads. In other areas of secondary intergradation the situation seems to be similar. In the light of the present knowledge one has a feeling that the hybridization of the greyheads and yellowheads, nowadays regarded as distinct species, is not so rare an event as most of the recent authors consider.

Sammalisto, L. (1961): An interpretation of variation in the dark-headed forms of the Yellow Wagtail. Br. Birds 54: 54-69.

1. Geographical variation in the dark-headed forms of the Yellow Wagtail (Motacilla flava) was studied by the analysis of four variables: the length of the supercilium, the amount of black on the head, the amount of white on the chin and throat, and the length of the hind-claw.
2. The populations could be separated into two groups: (a) those with a well-developed supercilium and very little black on the head (if any); (b) those with the supercilium lacking or reduced and much black on the head; and (c) those intermediate in both supercilium and amount of black on the head.
3. The area occupied by this thid group lies between the areas of the two. A characteristic of the intermediate population is the presence of moderate or considerable amounts of white on the chin and throat, whereas this characteristic is lacking or almost so, in the two other groups.
4. It is suggested that the first two groups are the parental types and the third their hybrid form. As the basis of variation is obviously polygenic (= determined by many genetic factors) and isolation is not complete, there are practically no pure populations and over vast areas the variation is considerable.(...)

Sammalisto, L. (1968): Variations in the selective advantage of hybrids in the Finnish population of Motacilla flava L. Ann. Zool. Fenn. 5: 196-206.

South Finland is an area of secondary intergradation, where a northern race of Motacilla flava thunbergi, and a southwestern race flava have met and formed a hybrid population. Intermediate males have a selective advantage over the parental races, whereas intermediate females have not. Hybrids are not uncommon in North Finland, but flava is never found there.
The proportion of intermediate males has decreased within the last 12 years in both South and North Finland. In the former, the decrease has not affected the population mean, since both parental races gained equally at the cost of the intermediates. But in North Finland, which flava cannot reach, obviously owing to inability to transgress the abrupt microclimatic shift at about the 65th northern latitude, only thunbergi has gained. Accordingly, the population mean approached the mean of the more extreme thunbergi populations of Norway and North Sweden, which are never under the influence of intermediate populations. The same shift also took place in South Finland some years later. It is postulated that this is due to population pressure from North Finland, whereas flava populations are separated from South Finland by seas and cannot have much influence on the variation in the intermediates.
The advantage of the intermediate males over the parental races is partly due to their high tolerance to cold at the nestling stage. This appears from their relatively high proportions in wet habitats, where the microclimate is arctic, and from their high frequency in years preceded by a cold nestling period.
Comparison of the 12 years' average population composition with that of the 65 preceding years (museum material) reveals no differences. Accordingly, random microclimatic fluctuations keep the long-term composition of the Finnish grey-headed wagtail population in equilibrium.
A further factor complicating the situation besides the absence of hybrid advantage in the females, is that thunbergi females prefer the habitat of flava males, and vice versa, whereas intermediates of both sexes prefer similar habitats, or at least not different ones.
Comparison of the Finnish hybrid population with other hybrid populations of grey-headed wagtails of similar origin indicates an important role of secondary intergradation as an adaptation mechanism in this species.

Schifferli, A. (1957): Über den herbstlichen Schafstelzendurchzug bei Sempach. Orn. Beob. 54: 135-136.

Smith, S. (1950): The Yellow Wagtail. London: Collins.

Sondell, J. (1993): Moult strategies of White Wagtail Motacilla alba and Yellow Wagtail Motacilla flava in central Sweden. Ornis Svecica 3: 107-116.

The wing moult of the White Wagtail Motacilla a. alba and the Yellow Wagtail M. f. flava has been recorded since 1973 at Kvismaren, central Sweden. Based on data from 558 White and 78 Yellow Wagtails in active moult the wing moult duration of the former was estimated at 55-65 days and of the latter at 35-40 days. The moult sequence was the same in both species. The only significant difference was the speed of the moult. The reason for this difference in moult strategy is probably the difference in migration destination of the two species. The Yellow Wagtail arrives later than the White Wagtail, stays a shorter time in central Sweden and starts the migration towards tropical Africa just before finishing the moult in the middle of August. Swedish White Wagtails winter in the east Mediterranean, arrive almost a month earlier and leave a month later. It is difficult to compare the present results with data from other parts of Europe as there are plenty of misrepresentations published some decades ago and quoted in later works. Therefore, methods of moult data evaluation are also briefly discussed.

Spaepen, J. (1957): De trek van de Kleine Gele Kwikstaart Motacilla flava L. Gerfaut 47: 17-43.

(French summary, here in translation) (...)Judging from the ringing results, the autumn migration is of broadfront character, with a pronounced southwest direction, leading to very strong concentrations along the Atlantic coasts of Europe. It seems as if these birds adopt the corridor used in autumn for the return migration as well, and in years to come; adults returning to their old breeding-place and juveniles to their birth area.
The migration speed varies between 30 and 240 kms per day; in sixteen cases the average speed was 72 km/day. But numerous retraps at sites where birds were ringed suggest, that there may be interruptions lasting from a few days up to two months (where?; CP) during the course of the migration journey.

Spina, F. & A. Massi (1992): Post-nuptial moult and fat accumulation of the Ashy-headed Wagtail (Motacilla flava cinereocapilla) in northern Italy. Vogelwarte 36: 211 - 220.

Svensson, S. (1957): Motacilla lutea flavissima BLYTH häckande i Sverige samt en översikt över gulärlekomplexet. Vår Fågelvärld 22: 161-181.

(Swedish breeding in Falsterbo 1960. No summary, but from the text in translation): My intention is not to determine lutea individuals racially with these comments, I only want to point to facts speaking for the likelihood, that birds observed really come from a lutea population and are not flava mutations.


Vaurie, C. (1957): Systematic Notes on Palearctic Birds. No 25. Motacillidae: the genus Motacilla. Am. Mus. Novit. 1832: 1-16.

Vepsäläinen, K. (1968): Structure of the Motacilla flava L. population in the border zone between south and north Finland. Ann. zool. fenn. 5: 389-395.

The southern intermediate population of Motacilla flava, composed of intergrading thunbergi and flava, meets the northern thunbergi population at the abrupt macroclimatic border between South and North Finland in Tornio - Kainuu. An intergradation population exists in the border zone between the southern and northern male populations. The intergrading zone is very narrow, being 10 - 20 km from south to north. In the study area in eastern Finland, the southernmost plot in which this intergradation population was observed was on latitude 64°14'.
In the southern population of the study area the proportions of the male parental types were the same. In the intergrading zone the proportion of the intermediates rose sharply and that of flava showed a steep decrease, while in the northern population the intermediates decreased as thunbergi increased. Thus the intergradation population differs from those of South and North Finland in both racial mean and the larger proportion of intermediates.
Although the races have different habitat preferences, the proportion of intermediates is larger than those of the parental races in all the habitats in the intergradation zone.
It seems that the change in the racial composition from south to north is more abrupt on treeless bogs than on those with a tree stand.
Reference to the literature of the late fifties indicates that a decrease in the proportion of intermediates has taken place in the populations near the intergradation zone of Tornio - Kainuu.
In females no integradation population can be found between the southern and northern populations, but the southern population changes into the northern one through a steep cline in the area of the male intergradation population.


Ward, P. (1963): Lipid levels in birds preparing to cross the Sahara. Ibis 105: 109 - 111.

(from the text) It often proved impossible to allocate even a freshly moulted male to one of the accepted geographical races. (...) In so far as the specimens provide a sample which overlaps in time the main spring migration period, it is probably justifiable to conclude that O. oenanthe and M. flava put on 30 - 40 % of their body weight in fat before setting out to cross the desert.

Ward, P. (1964): The fat reserves of Yellow Wagtails Motacilla flava wintering in southwest Nigeria. Ibis 106: 370-375.

The fat contents of 85 Yellow Wagtails wintering at Ibadan, southwest Nigeria, have been determined. The mean fat value remained fairly constant at around 5 % of their body-weight from October till March, with a rapid increase in April to 20 - 30 %, and a maximum recorded value of 30.6 %. These fat deposits are of similar proportion to those found elsewhere in long-distance migrants about to make a sea or desert xcrossing, though the initial 800 km of the northward journey made by Ibadan birds is over country where food and water is plentiful.
The pattern of fat acquisition, plumage characters, and other considerations suggest that the population sampled must breed in the belt where the ranges of Motacilla f. flava and M. f. thunbergi overlap, probably in Scandinavia.

Williamson, K. (1955): Migrational drift and the yellow wagtail complex. Brit. Birds 48: 382-403.

1. The evidence that the yellow or flava wagtails are in an unusual state of "genetical instability", certain populations producing mutants which exhibit remarkable convergence with birds of other forms, shows certain anomalies and inconsistencies which invite a re-examination of the problem.(...)
3. It is suggested that the "convergence" or "spontaneous mutation" can be best interpreted as vagrancy resulting from migrational drift during the return from winter-quarters, consolidated by a readiness to mix on the part of the various forms, their close identity of migratory behaviour and biology, and the importance of the head-colour as a recognition character (so-called "migrational drag").
4. The yellow-headed "var. lutea", supposed by some authors to arise by "spontaneous mutation" in the grey-headed M. f. beema population of the central Palaearctic region, may receive increments from flavissima stock by recurrent trans-Saharan drift at the outset of spring migration, resulting in a mixed population in southern Russia of which a small part cannot be differentiated from the British bird.
5. Evidence that the yellow-headed taivana and lutea are synpatric with grey-headed forms, whilst flavissima and flava have a slight overlap in western Europe, the two groups maintaining their distinctness in each case, justifies the recognition of two species of yellow wagtails, M. lutea and M. flava.(...)

Wood, B. (1978): Weights of Yellow Wagtails wintering in Nigeria. Ringing & Migration 2: 20-26.

This paper discusses the weights of Yellow Wagtails caught at a roost in central Nigeria during the winter. Despite the apparently harsh environment, there is no evidence that these birds accumulate long-term reserves to assist their survival during the most difficult part of the dry season. This is in contrast to the situation found in many high-latitude birds in winter. Both sexes adjust their evening weight in order to maintain a constant weight at dawn, although males exhibit a greater variability in dawn weights than females. This is apparently correlated with early pre-migratory fattening in males.
Histograms of dusk and dawn weights of each sex are presented. Dawn weights are useful for comparison with migrants of low weight, indicating stress in the latter. The higher weights of males enable them to more readily overcome difficult feeding conditions than females.

Wood, B. (1979): Changes in numbers of over-wintering Yellow Wagtails and their food supplies in a West-African Savanna. Ibis 121: 228-231. No summary.

(from text) Since Yellow Wagtails are present in almost all regions of Nigeria throughout the winter, Elgood et al (1966) specifically excluded the species from the category of migrants which move soutwards as the dry season progresses. Yet, since this wagtail exhibits a fairly pronounced latitudinal zonation of races in winter quarters (Wood 1975), it seems urprising that movements of the magnitude suggested by numerical changes at Vom (07°32'N, 03°56'E) have hitherto remained undetected. Failure to do so may be attributed to the difficulty of critical differentiation of subspecies in the field; while adult males present least difficulty, females and immatures may be almost impossible to separate.
At Vom, the nominate subspecies M. f. flava predominated throughout the winter 1973 - 74, and changes in the representation of adult male M. f. thunbergi, the only other subspecies occurring in any number, showed no consistent trend. As many adult males are territorial, and therefore (as observed) largely sedentary, this section of the population is probably least useful as an indicator of change in latitudinal distribution. Perhaps only when more detailed numerical studies are available will the full extent of itineracy in this, and possibly other Palaearctic migrants, be appreciated.

Wood, B. (1982): The trans-Saharan spring migration of Yellow Wagtails. J. Zool. London 197: 267-283.

By considering the weights of the heaviest members of a population of Yellow wagtails about to emigrate from northern Nigeria, estimates of the mean weight of each sex at take-off are derived. These are used to predict changes in weight and flight speed during a non-stop trans-Saharan flight. For most birds the duration of this flight will be 60-70 h, enabling them just to attain the northern side of the desert. Some birds may resort to partial dehydration to achieve this, but extensive dehydration is not apparent for most birds caught towards the end of the flight. It is apparently essential that favourable winds occur during the flight; even slight head winds are likely to produce heavy mortalities. Because Yellow wagtails depart on a trans-Saharan crossing with just enough reserves to achieve this, adverse winds, difficult conditions immediately north or south of the desert, or any avoidable extension of the flight are all likely to impose considerable selection pressures. Therefore, probably all Yellow wagtails move gradually northward in Nigeria, to the southern margins of the desert, where they may still obtain adequate food, and there await favourable meteorological conditions before embarking.


Zink, G. (1976): Der Zug europäischer Singvögel. Ein Atlas der Wiederfunde beringter Vögel. Lieferung 2. Möggingen.

Zink, G. (1977): Richtungsänderungen auf dem Zuge bei europäischen Singvögeln. Vogelwarte 29, Sonderheft: 44-54.


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