Moult papers:

references, abstracts and comments. Where there is no abstract, an abstract has been written, where abstracts are too long they have been abridged, where the English is poor it has been improved. Abstracts/summaries in languages other than English have been translated into English, some extremely bad abstracts (and even headings) from Ringing & Migration have been corrected when called for. The comment is personal, it points out errors and possible follow-ups, it is begun: CP:

ascending (ascendent, ascendant) primary moult: begins with the outermost primary.
descending (descendent, descendant) primary moult: begins with the innermost primary.
distal primary: the most distant ones from the body
prebasic molt (am.) = postnuptial moult
proximal primaries: the ones closest to the body
transilient mode: from the last moulted remige there is a forward or backward jump, omitting one or several intermediary remiges.
dorsal: on the back side
ventral: on the belly side

S, T, U, V, W, X, Y, Z

Sach, G. (1968): Die Mauser des Grossen Brachvogels Numenius arquata J. Orn. 109: 485 - 511.

The Curlew's postnuptial moult covers a period of 70 to 80 days.
Northern breeding birds start their moult as soon as they have reached the moult places in the outer Jade area at the end of June or at the beginning of July. A considerable part of them spend their moulting period in special resting places. By the end of September or beginning of October they continue their migration to the winter-resorts.
Juvenile birds stop their spring migration at places which are visited later on by moulting adults. From mid-May on they start a complete moult lasting till September, after which they leave this area together with the adults.(...)
The six inner primaries are often moulted almost simultaneously. This stage requires an increase of wingstroke-frequency from about 240 to about 280 strokes/min in the case of head wind or lull, if the speed of the non-moulting birds is to be attained. It is therefore assumed that wing-moulting Curlews are unable to cover great distances.

Salewski, V., Altwegg, R., Erni, B., Falk, K. H., Bairlein, F. & B. Leisler (2004): Moult of three Palaearctic migrants in their West African winter quarters. J. Orn. 145: 109 - 116.

Some theories about moult strategies of Palaearctic passerine migrants assume that birds adapt timing of moult to environmental conditions such as rainfall on their African wintering grounds. Species wintering in the northern tropics should limit moult to the period shortly after their arrival at the end of the rainy season. Passerine migrants wintering in West Africa should also moult more rapidly compared to related species or conspecific populations that moult elsewhere. We investigated the moult of melodious warblers Hippolais polyglotta, willow warblers Phylloscopus trochilus and pied flycatchers Ficedula hypoleuca wintering in Comoé National Park, Ivory Coast, between October 1994 and April 1998. In contrast to previous studies we did not restrict our analyses to moult of flight feathers but also included moult of body feathers. The results differed partially from the general assumptions of previous authors. Melodious warblers moulted twice: a complete moult shortly after their arrival, and a moult of body feathers and in some cases some tertials and secondaries in spring. Willow warblers moulting flight feathers were found between December and March with the majority moulting in January and February. Primary moult was not faster compared to populations moulting in central Africa and South Africa. Body feather moult varied strongly among individuals with birds in heavy moult between December and April. Pied flycatchers moulted body feathers and tertials between January and April. Birds with growing feathers were found throughout the whole period including the entire dry season. Moult strategies are thus not readily related to a few environmental factors in general and our results show that factors other than mere resource availability during certain times on the wintering grounds are likely to govern the timing of moult.

Salomonsen, F. (1945): Notes on the Variation and Moult in the Willow-Warbler (Phylloscopus trochilus (L.)). Ark. Zool. 36A: 1 - 13.

Schmutz, J. K. & S. M. Schmutz (1975): Primary moult in Circus cyaneus in relation to nest brood events. Auk 92: 105 - 110.

A study of 112 breeding adult Marsh Hawks in central Wisconsin from 1959 through 1973 revealed a high correlation between date and primary molt. We found no significant correlation between primary molt and such nest brood events as hatch date and the number of young fledged. Breeding males begin primary molt later than breeding females but proceed at a faster rate. Both sexes have more primaries incoming at once and thus a larger gap in the wing in the early part of the molt sequence than later.

Schönfeld, M. & R. Piechocki (1974): Beiträge zur Grossgefiedermauser der Schleiereule, Tyto alba guttata.. J. Orn. 115: 418 - 435.

In an investigation of wing and tail moult of barn owls from 1969-1972, 39 adult and 99 juvenile birds were marked by banding and by clipping primaries, secondaries and tail feathers.
During this period 10 juvenile and 24 adult birds were found dead or were caught again, some of them up to ten times. It could be shown that the barn owl also exhibits some peculiarities in its moult and that it is interesting from other points of view as well.
The first wing and tail moult of juvenile birds takes three years not counting the first year of life. The moult is neither postnuptial nor praenuptial; rather, it is related to the season and, probably, to the breeding cycle. Breeding cycle and age may differ by up to six months because young birds may leave the nest not only in May but also in November but both may be found breeding in the following year.
The first complete moult of juvenile birds may be divided into three periods which correspond to years. During the first period (second year of life) the moult takes place at the primaries over P6 (P6 is the focus and is often moulted alone at an age of c400 days; CP), sometimes H7; during the second period (third year of life) over P7, 5, 8, sometimes P4, 9 and ends during the third period (fourth year of life) with change of the remaining primaries (PIECHOCKI 1974). In older birds the second generation of P6, 7, 5 is growing before the moult of the preceeding generation especially P1, 2, 3 has been completed. Older barn owls usually moult the primaries within two years. P6, 7, 5 are dropped simultaneously on both sides, P6 is a little ahead. (...) The difference between the first complete moult and the old age moult is explained as follows: During the period of November/December to April the barn owls do not moult and juvenile birds must adapt to the seasons in the first four years of life. This sis due to the fact that the juveniles fledge (...) from May through November (December) which is unusual for Central Europe. The timing of the first phase of the first complete moult is dependent upon individual age, whilst the moult of older birds seems to be controlled by the season of the year. The moult of the secondaries begins in the first moult phase (second year of life) starting from a focus S12 over S13, S14, sometimes also S11. During the second moult phase (third year of life) the moult is continued from three foci S2, S5 and S11. During the second moult phase nearly all secondaries which have not been changed during the first moult phase are usually changed.
It therefore seems useful to divide the secondaries into "action goups". Within the action groups the change of individual feathers may differ. The moult of the tail begins during the first moult phase (second year of life) with the pair R6 immediately after P6 has been dropped. Then, pair R1 is changed while other tail feathers are changed apparently without rule. The results of PIECHOCKI (1961) and (1974) regarding the moult of the secondaries are confirmed for the first and second phase but the change of all distal secondaries in the second moult phase was not observed. The distal primaries follow from focus P6 in a descending mode and the proximal secondaries in an ascending mode. In at least some wild birds, well defined differences may be found between older feathers and freshly moulted feathers, especially primaries 8 to 10.(...)

Serra, L. & R. Rusticali (1998): Biometrics and moult of Grey Plover (Pluvialis squatarola in northeastern Italy. Vogelwarte 39: 281 - 292.

Grey Plovers wintering in northeastern Italy were morphologically closer to the populations which use the East Atlantic Flyway than those following eastern routes, but differences in biometrics appeared too small for reliable considerations on breeding origins. Body mass seasonal variations showed a clear mid-winter peak, reaching 250 g both in adults and first-years. No body mass increase was observed in spring, suggesting early, short movements to pre-migratory staging areas where energy reserves are accumulated. Adult primary moult was estimated at 93 days, with mean starting date on 18 August and mean closing date on 19 November. Two concurrently active primary moult cycles were observed on second year birds in September-October.

Sibley, C. G. (1957): The abbreviated inner primaries of nestling woodpeckers. Auk 74: 102 - 103.

End of note: (...) The reason why woodpeckers should be unique in this respect (if indeed they are) is probably related to their long period of nestling life. It is well known that the woodpeckers, and their relatives the toucans, honey-guides, and barbets, have relatively short incubation periods but exceptionally long periods of nestling development before fledging.
It seems possible then, that the abbreviated inner primaries of nestling woodpeckers are an adaptation to nest life, which also provides a metabolic saving, and that the evolution of this condition has been possible because of the unique combination of a complete post-juvenal molt, beginning with the inner primaries, and an unusually long period of nestling life.

Snow, D. W. (1969): The moult of British thrushes and chats. Bird Study 16: 115 - 129.

An analysis is presented of the timing and duration of the moult in British Turdidae, from records collected by the Moult Enquiry of the BTO.(...)
The mean duration of the moult in the Blackbird is estimated at 85 days. First-summer birds start to moult a little earlier than older birds (mean dates 26 June and 4 July). The standard deviation of the dates of onset of the moult indicates a rather exact proximate timing mechanism, when account ios taken of the fact that the date of the start of the last nesting attempt introduces an independent source of variation. The proximate factors controlling the onset of breeding work less precisely.(...)

Snow, D. & B. Snow (1976: Post-breeding moult of the Lapwing. Bird Study 23: 117 - 120.

Wing and tail feathers dropped by individuals of a roosting Lapwing flock were collected at regular intervals by the authors. (from text)...the following identifications can be made with some confidence:
all black, less than 145 mm = P1; all black, 150 - 160 mm = P2; white spot on outer web only, more than 180 mm = P7; white on both vanes, less than 164 mm = P10.

Sondell, J. (1977): Sävsparvens Emberiza schoeniclus ruggning i Kvismaren. Vår Fågelvärld 36: 174-184.

Abstract from summary: According to regression TIME on MOULT SCORE (P+S) the moult of the Reed Bunting at Kvismaren covers 55.3 days. The mean start of moult was 13 July. In 95 % of the population the spread in starting time is 34 days. All birds are moulting 30 July to 20 August.(...)
Calculated from recaptures, the duration of individual moult was 60.5 days. In 1974 there was a 4-day delay in starting time because of cold and rainy weather. Birds in their 3rd calendar year or more started to moult four days later relative to 2nd calendar year birds.(...)
Many moult analyses are based on scatter diagrams of the primary score in relation to date. In order to estimate the duration of moult, a linear relation between these two parameters is fitted by the eye. This method is rather primitive. First, the primary moult does not proceed linearly. Secondly, the period of primary growth doesn't cover the whole moult period.(...)

Sondell, J. & E.-B. Schildt (1985): Bofinkens ruggning i Kvismaren. Medd. från Kvismare Fågelstation 54: 2 - 8.

Sondell, J. (1987): Fyra trastarters ruggning i Kvismaren. Vår Fågelvärld 46: 55-63.

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.

Sondell, J. (2000): Wing moult duration for the Reed Bunting Emberiza schoeniclus at Kvismaren, central Sweden, with regard to data representativeness and weather influence. Ornis Svecica 10: 13 - 23.

I have analysed 1777 moult records of the Reed Buntings Emberiza schoeniclus, collected at Kvismaren, central Sweden, in 1973-1995. When evaluating moult with regression techniques it is important that the data are representative primarily with respect to the start and the end of the moult period. Otherwise a too short period is obtained. The mean moult duration was estimated to be 63 days, starting on 10 July. The females started to moult 6 days later and finished moult 3 days later than the males. Weather conditions significantly affected the moult performance. The variation in mean annual onset of moult ranged from 3 to 17 July. The temperature in April, May and to some extent also in July had a significant innfluence on the onset. Warm versus cold summers introduced a variation of only about 3 days in the duration of the moult but under extreme conditions (snow in spring and warm summer versus warm spring and cold summer) the variation between years in the mean duration of the moult was as much as 10 days.

The Least Sandpiper in Surinam, South America. Bird Banding 47: 359 - 364. Internetversion av denna uppsats.

Primary molt in adult Least Sandpipers trapped in Surinam started between early August and mid-September. For the entire population the period of primary replacement lasted about five months. Secondary molt began when the primary score was between 25-30 and tail molt when the primary score was between 15-30. Before all primaries were replaced secondary molt was completed in all, and tail molt in most birds. All immatures underwent a flight feather molt, involving a varying number of outer primaries and in some instances perhaps inner secondaries. There was a negative correlation between primary molt score and weight, indicating that the species may be subjected to physiological strain during the molt of the flight and tail feathers.

Spina, F. (1990): First data on complete summer moult in the Great Reed Warbler Acrocephalus arundinaceus in northern Italy. J. Orn. 131: 177 - 178.

Complete summer moult in the great Reed Warbler (Acrocephalus a. arundinaceus) is a rare phenomenon, and only two cases have so far been reported for Europe. In five years of summer ringing in Val Campotto, Northern Italy, 12 different individuals were found in complete moult. Only the two innermost primaries are generally renewed, with more advanced stages of moult involving up to six primaries, the tertials and the first secondaries. A single bird controlled in three subsequent years was always found at a similar degree of primary moult.

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.

Ashy-headed Wagtails (Motacilla flava cinereocapilla) studied in Val Camporto (Northern Italy) start complete moult in July, and by the beginning of September the whole wing is fully renewed. (...) Primaries are not dropped with a linear sequence, possibly also in relation to the onset of secondary moult; a clear difference in moult sequence is found between the five innermost (P1-P5) and the outermost primaries (P6-P10). The difficulties related to such non-linear patterns in the calculation of moult duration through different methods are discussed. Juveniles and adults leave the area with considerable fat depots, and adults in particular quickly accumulate energy reserves after completion of moult.

Steiner, H. M. (1970): Die vom Schema der Passeres abweichende Handschwingenmauser des Rohrschwirls (Locustella luscinioides). J. Orn. 111: 230 - 236.

In three out of four adult Savi's Warblers (Locustella luscinioides) in autumn in Neusiedl am See (Austria), the primaries were renewed in an ascending and descending pattern from a centre in their midst. The fourth bird had new inner primaries, the outermost three only being old. It is impossible to decide whether in this case all primaries were replaced in a descending pattern or if an ascending replacement took place prior to the descending. The descending pattern of moult in the primaries of most Passerines is given up in the Savi's Warbler in relation with itslife in dense reed beds where it is able to live flightless in late summer. So the species can afford a considerable individual variability in speed of moult in various parts of the wing, asymmetry in the pattern of moult, and the renewal of a large number of wing feathers at the same time.
Moult in secondaries occurs as usual with the Passerines; following the renewal of the innermost three, the remaining feathers are replaced in ascending pattern. The time of moult in the primaries and secondaries seems to be well-correlated.
The tail feathers are shed at very small intervals and this, together with frequent accidental loss of some of them, is responsible for the fact that the centrifugal plan of moult is not realized exactly.(...)

Stresemann, E. & V. Stresemann (1960): Die Handschwingenmauser der Tagraubvögel. J. Orn. 101: 373 - 403.

The modes of the wing-moult. - A peculiar way of moulting the ten primaries was shown to be shared by all members of the family Falconidae (V. STRESEMANN, 1958), as opposed to the Accipitridae. In the present investigation the authors studied the rest of the order Accipitres (=Falconiformes) by the same method. In the family Accipitridae, the moult of the primaries starts either with the innermost (= first) one, to end with the distal one, or the moult fails to follow any regular sequence. The former mode, called by HEINROTH the descending moult, has been termed "mode 2" in this paper; the other (irregular) mode has received the sign "mode 3b". With a number of species, the moult follows mode 2 in the juvenile wing and mode 3b in the adult wing. This is "mode 3 a" of the authors. Not a single member of the Accipitridae moults the wing after the manner of the Falconidae, i.e. by starting with the fourth primary ("mode 1")
The descending moult is considered by the authors to be primitive, and the irregular moult to be derived from the former; both stages are still connected by mode 3 a, which recapitulates in ontogeny the phylogenetic process.
Mode 3 a and mode 3 b are most frequently found in large species, mode 2 almost only in smaller species of Accipitridae. This may be explained by the following consideration: It takes more time to replace the longest (and most effective) primaries of the larger species than of the smaller ones. Therefore any wing containing large sized primaries would become considerably less effective if moulted quicly in a regular descending way. The same result can be achieved in the same time and with far less weakening of the wingstroke, if the quills which drop consecutively (or even at the same time) are separated by full-grown ones, instead of being immediate neighbours.
The irregular moult generally starts from 3 (or even 4) "centres", the position of which is subject to considerable variation. From these isolated centres the process of moult proceeds towards neighbouring feathers in the outward or (and) the inward direction, or the neighbours remain unaffected. Considerable disturbances of symmetry between left and right wing are of frequent occurrence.
The mode of moult depends not only on body size or wing load, for there are well defined genera in which all species, large and small, belong to the same category of moult. In certain other natural groups there is no uniformity in the mode of moulting. Gypohierax, for one instance, differs in this respect from the rest of the vultures.
Chronology of moult. - The start of the wing-moult is determined by other biological requirements than the time of egg-laying. The latter has been adjusted to the needs of the species (i.e. to the benefit of the prospective offspring), while the former provides for the needs of the individual itself. The primary moult takes place in some holarctic Accipitres a considerable time after the breeding period; all the species in question evade the hardships of the northern winter by migrating to the tropics, and, therefore, can afford a winter moult. Other holarctic species start dropping the primaries during the egg-laying period or even earlier; most of these species spend the unfavorable time of the year within, or not far from, the breeding area, and are therefore moulting during the fine season. These two extremes are connected by intermediate links.
The female starts to moult her primaries before her mate in Accipiter nisus, Accipiter gentilis and apparently some other species. This sexual difference is obviously the consequence of the fact that it is the task of the male to provide the incubating female with prey hunted on the wing. During this period his flying power has to be at its best.
The duration of a complete wing moult differs according to species. With small andmedium-sized species this process takes six months at the most (up to 171 days in Accipiter gentilis). It seems probable, but has not yet been definitely proved, that the great eagles and vultures extend the moult of the ten primaries over a period of more than one year.
The rate of growth of a primary depends not only on its length (long feathers usually grow faster than short ones), but also on season (i.e. on periodic changes of thyroxine level?).(...)

Stresemann, E. & V. Stresemann (1961): Die Handschwingen-Mauser der Kuckucke (Cuculidae). J. Orn. 102: 317 - 352.

The article deals with the sequence in which the primaries are shed in the family Cuculidae. About 300 specimens, representing almost every genus, were examined.
In this family, the primaries are not moulted in the descending mode, but follow the transilient mode. This new term means that the moult proceeds by forward or backward leaps across one or more adjoining quills.
While growing, each primary (except the outermost one) is flanked on both sides by a fullgrown neighbour, no matter to which generation the latter may belong.
With the random transilient mode neither the centre or the centres which form the starting point of the wing moult, nor the distance of the leaps are fixed.
The occurrence of the orderly transilient mode is restricted to certain parasitic cuckoos of the Eastern Hemisphere (subfamily Cuculinae), its feature being that the moult centres are identical in most individuals, and that the distance of the leaps is likewise genetically controlled.
The simplest regulation is that of Urodynamis. It consists in a strictly alternating moult of the primaries which starts with the odd ones followed by the even primaries after the former are fullgrown.
In other genera one of the characteristics of primary moult is the interlocking of two shedding rhythms. One of the affects the distal primaries, the other one the (4 or 5) proxima ones; both proceed synchronously. This is especially evident with the Eudynamis mode and the Cuculus mode. The latter is the most rigid and thus the most highly developed rhythm.
The Eudynamis mode occurs only in Eudynamis, while theCuculus mode is shared by the genera Cuculus, Cacomantis, Misocalius, Chalcites and Chrysococcyx. Surniculus moults its primaries in a looser way, but still similar to Cuculus. By its mode of moult Hierococcyx differs from Cuculus, and Penthoceryx from Cacomantis. The transilient moult of Scythrops, Clamator, Caliechthrus (and probably Cercococcyx too) is, like that of the non-parasitic Cuckoos, not genetically controlled.
The authors consider the mode of primary moult an important criterion of affinity. Their arrangement of the genera belonging to the cuculinae differs from that proposed by J. L. Peters in 1940.

Stresemann, E. & V. Stresemann (1961): Die Handschwingen-Mauser der Eisvögel (Alcedinidae). J. Orn. 102: 439 - 455.

Judging from the mode of moulting the primaries, the family of Kingfishers (Alcedinidae) consists of three well-defined groups. These groups agree exactly with the three subfamilies Daceloninae, Alcedininae and cerylinae, as classified in 1912 by W. De W. Miller, who based his arguments on morphological evidence.
The Daceloninae (including Pelargopsis) follow the descending mode, by beginning with the innermost (first) primary.
The Alcedininae too moult the primaries in a descending way, beginning, however, from two centres, one represented by the first, the other by the seventh quill. With the Cerylinae, the moult of primaries is more or less irregular and never according to the descending mode.

Stresemann, V. (1963): Zur Richtungsumkehr der Schwingen- und Schwanzmauser von Muscicapa striata.. J. Orn. 104: 101 - 111.

Stresemann, E. (1963): Variations in the numbers of primaries. Condor 65: 449 - 459.

Beginning with Jeffries' article (1881) the remicle has generally been considered homologous to a primary. Quite a tower of additional theories has been erected on this supposition, which the present author believes to be erroneous. The essence of this article may be explained by comparing it with the "classic" concept.
A. Number and distribution of functional primaries in the ancestry of modern birds: Current view: Total number of primaries 12, Metacarpal remiges: 7, Predigital remiges: 2; Autor's view (of same sequence): 10 - 6 - 1.
B: Function of remicle in ancestral wing: Current view: A primary. Author's view: A covert to the terminal claw.
C. Evolutionary trend in the number of functional primaries: Current view.--A decrease in all groups of flying birds (from 12 to 11 in Podicipedidae, Ciconiidae, Phoenicopteridae; from 12 to 10 in most other largeer birds; from 12 to 9 in most Passeriformes, some Piciformes and some flightless rails). Author's view.--No change in almost all groups of birds. Exceptions: increase in Podicipedidae, Ciconiidae, Phoenicopteridae, where the number of metacarpal primaries has been increased from 6 to 7 by intercalation, bringing the total number of primaries from 10 to 11; decrease from 10 to 9 by gradual reduction of the outermost primary in most Passeriformes and some flightless rails.

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

Stresemann, E. & V. Stresemann (1968): Die Mauser von Anthus campestris und Anthus richardi. J. Orn. 109: 17 - 21.

Some (many?) adult specimens of Anthus campestris and Anthus richardi leave the breeding area before replacing all worn primaries, secondaries and rectrices by new ones. In such a case, they migrate to their winter quarters with a mixture of new and old feathers, all fully grown, and it is only there that the "postnuptial" moult is continued and concluded. In Anthus richardi a strong tendency has been found to deviate from the regular descending sequence which is followed by almost all other palearctic Passeriformes while moulting the ten primaries.

Stresemann, E. & V. Stresemann (1968): Winterquartier und Mauser der Dorngrasmücke, Sylvia communis. J. Orn. 109: 303 - 314.

Examination of about 170 skins of Sylvia communis, in the majority collected in African winter quarters, led to the following conclusions:
1.) Adults of European populations undergo a complete postnuptial moult in July/August before migrating to Africa, while the Asiatic populations have a complete moult in winter quarters, usually starting in January or February and ending in late February or in March. Young birds hatched in Europe renew the flight feathers for the first time when about 12 months old, thus at the same time as the adults. On the other hand, young birds of Asiatic origin moult the flight feathers in first winter (usually in Jan./Febr.) at the age of 6 months.
2.) The seasonal differences of complete moult proves to be a reliable criterion for determining the winter quarters of European and Asiatic Common Whitethroats.
a) European populations (S. c. communis) - Winter quarters confined to African countries north of the equator.
b) Asiatic populations (S. c. icterops and "volgensis") - Winter quarters mainly south of the equator, as far south as Nyasaland and Rhodesia (a few even reaching Transvaal and Damaraland).
The winter quarters of both groups overlap in Ethiopia, Kenya, Uganda and in the surroundings of Lake Albert.
3.) A partial moult, confined to body, tertials and sometimes central tail feathers, takes place in the European populations about Jan./Febr., in the Asiatic populations about July.(...)

Stresemann, E. & B. Stephan (1968): Über das remicle. J. Orn. 109: 315 - 322.

In all well-flying birds the rachis of the three distal primaries is attached to the bones of the second digit. Two of them are supported by its basal phalanx, and the most distal one by its second phalanx.
In many species of birds a tiny stiff feather, hidden by coverts, is found in front of the distal primary. This is the so-called remicle. It is fixed near, or at, the extremity of the terminal phalanx and has its own aversed greater under covert. We consider the remicle to have never participated in propulsion of the flying bird during avian evolution. This view is opposed to that of WRAY and STEGMANN, who took the remicle to be the dwarfed remnant of a long and flight-supporting primary.
In certain orders or families of birds the remicle is present in all species. Other groups consist of species with and others without the remicle. The nature of the factors which promote the reduction of the remicle and its total disappearance remains uncertain. In some cases this little feather seems to have gained its special function.

Stresemann, E. & V. Stresemann (1968): Im Sommer mausernde Populationen der Rauchschwalbe Hirundo rustica. J. Orn. 109: 475 - 484.

In most populations of Hirundo rustica the moult begins after the birds had reached, in September or October, their distant winter quarters. This is, however, not the case with the southernmost populations. These are either residents, or they do not migrate in autumn farther than some hundred miles. They start the moult, if adult, immediately after (or before?) the last breeding cycle (at the end of June or in July), and are in completely new plumage after abouth 4 1/2 months. To this group belong: H. r. savignyii, H. r. transitiva and the populations of H. r. rustica nesting at the southern border of the Himalayas and in Southern Afghanistan.
The young of these "summer-moulting" populations may begin the complete moult at the age of about 4 months, in July or August. They wear the adult plumage from November, December or January on.
The authors suppose that the southernmost (subtropical) populations of the East-Asiatic subspecies H. r. gutturalis may equally start to moult in summer.

Stresemann, E. & V. Stresemann (1970): Über die Vollmauser des Rohrschwirls Locustella luscinioides. J. Orn. 111: 237 - 239.

1. Specimens of Locustella luscinioides undergoing and finishing the complete annual moult have been encountered not only in winterquarters (Darfur, in October/November) but also in Europe (Austria and Northern Germany, in August/September). This fact may, or may not, be due to individual rather than geographical variation of the species with regard to the onset of moult.
Six skins in wing moult were studied by the authors. In each case the sequence in primary replacement conformed with the usual passerine pattern.

Stresemann, E. & V. Stresemann (1970): Über Mauser und Zug von Puffinus gravis. J. Orn. 111: 378 - 393.

1. specimens of Locustella luscinioides undergoing and finishing the complete annual moult have been encountered not only in winterquarters (Darfur, in October/November) but also in Europe (Austria and Northern Germany, in August/September). This fact may, or may not, be due to individual rather than geographical variation of the species with regard to the onset of moult.
Six skins in wing moult were studied by the authors. In each case the sequence in primary replacement conformed with the usual passerine pattern.

Stresemann, E. & V. Stresemann (1970): Die Vollmauser der Schneeammer Plectrophenax nivalis. Beitr. Vogelk. 16: 386 - 392.

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.

Summers, R. W., L. G. Underhill, C. F. Clinning & M. Nicoll (1989)Populations, biometrics and moult of the Turnstone Arenaria interpres, with special reference to the Siberian population. Ardea 77: 145 - 168.

Three populations of Turnstone were studied. Primarily a series of comparisons was made between the Canadian-Greenland population which winters mainly in western Europe and the Siberian population which winters partly in southern Africa. There was no long term change in the size of the latter population over the period 1976 to 1989. (...)The duration of primary moult of 1y+ Siberian birds was about 45 days longer than that of Canadian-Greenland birds; it started two months later and was less synchronized. Of first-year Siberian birds, 32 % of the population undergo partial wing moult whereas no first-year Canadian-Greenland birds moult.

Sutter, E. (1956) Zur Flügel- und Schwanzmauser des Turmfalken (Falco tinnunculus). Orn. Beob. 53: 172 - 182.

Sutter, E. (1975) Zur Grossgefiedermauser der Schleiereule. Orn. Beob. 72: 199 - 202.

(Short note, transl. from text) The findings from our material confirm the validity of Schönfeld & Piechocki's results. Like other Barn Owl populations Swiss birds distribute the exchange of the juvenile plumage over a period, that may embrace not only three, as earlier shown, but even four moulting periods. Probably owing to the particular surface structure owl feathers wear less rapidly than other bird feathers. This makes a longer-than-normal durability possible: most remiges of the first generation are used for at least two years in the Barn Owl, the most exposed outer primaries even for three years and the innermost for four years.

Swann, R. L. & S. R. Baillie (1979): The suspension of moult by trans-Saharan migrants in Crete. Bird Study 26: 55 - 58.

A higher incidence of suspended moult is found among trans-Saharan migrants on passage in Crete than in Iberia. Evidently east European birds have less time to complete their moult before autumn migration, and this is probably linked to later breeding seasons.


Thomas, D. G. & A. J. Dartnell (1971): Moult of the Red-necked Stint. Emu 71: 49 - 53.

Thomas, D. G. & A. J. Dartnell (1971): Moult of the Curlew Sandpiper in relation to its annual cycle. Emu 71: 153 - 158.

Thomas, D. K. (1977): Wing Moult in the Savi's Warbler. Ring. & Migr. 1: 125 - 130.

Thomas, D. K. (1979): Wing Moult in the Fan-tailed Warbler. Ring. & Migr. 2: 118 - 121.

Thönen, W. (1965): Zur Schwingenmauser des Tüpfelsumpfhuhns. Orn. Beob. 62: 64 - 66.

Tiainen, J. (1981): Timing of the onset of postnuptial moult in the Willow Warbler Phylloscopus trochilus in relation to breeding in southern Finland. Orn. Fenn. 58: 56 - 63.

The timing of the postnuptial moult was studied in the Willow Warbler, a long-distance migrant whose breeding grounds offer favourable conditions for a restricted period. Altogether 92 individuals were examined in southern Finland, including 21 males and 39 females whose exact stage in the breeding cycle was known.
Both sexes started moulting independently of the breeding stage, females probably about 10 - 15 days later than males. The moulting rate seems to be slower in early moulting individuals than in later ones, differing both within and between sexes. The earliest moulters may be those whose nests are destroyed.
In Finnish Willow Warblers adjustment to the short summer is achieved by a rapid rate of moulting and overlap between breeding and moulting.


Ullrich, B. (1974): Über die postnuptiale Mauser des Rotkopfwürgers Lanius senator. J. Orn. 115: 80 - 85.

Lanius senator has two periods of moult annually. At summer the postnuptial moult on the breeding grounds includes primarily the body plumage but also inner secondaries and without rule feathers of the tail. (Second calendar year birds) whose first prenuptial complete moult in the winter quarters is incomplete, begin partially with the moult of primaries already on the breeding grounds, stop it before migration, and resume it in the winter quarters. The complete renewal of wings and tail takes place in the second winter. The postnuptial moult does not begin earlier than the end of June, when juveniles have been fledged several weeks, and is probably finished no later than the end of August immediately before migration.

Underhill, L. G. & R. P. Prys-Jones (1986): The primary moult of Common Tern in the Southwestern Cape; A recording system, observed patterns, and an appeal for information. Safring News 15: 44 - 49.

Underhill, L. G. & W. Zucchini (1988): A model for avian primary moult. Ibis 130: 358 - 372.

The regression methods frequently used to estimate the parameters associated with primary moult in birds are unsatisfactory. Results obtained using least square regressions, and various ad hoc adaptations, are so obviously incorrect that many authors have fitted lines 'by eye' (Newton 1968, Thomas & Dartnall 1971, Elliott et al. 1976, Appleton & Minton 1978). In a comparison of seven regression methods, estimates of the average starting date varied between 29 June and 31 July, completion date between 2 and 24 October, and duration of moult between 72 and 109 days for the Redshank Tringa totanus, in spite of the very large sample of 1482 observations (Summers et al. 1983). In this paper we present a new approach to the analysis of primary moult and develop a mathematical model specifically designed for moult data.

Underhill, L. G., Zucchini, W. & R. W. Summers (1990): A model for avian primary moult: data types based on moult strategies, illustrated by an example using the Redshank Tringa totanus. Ibis 132: 118 - 123.

Underhill, L. G., Prys-Jones, R. P., Dowsett, R. J., Lawn, M. R., Herroelen, P., Johnson, D. N., Norman, S. C., Pearson, D. J. & A. J. Tree (1992): The biannual primary moult of Willow Warblers Phylloscopus trochilus in Europe and Africa. Ibis 134: 286 - 297.

Underhill, L. G. & A. Joubert (1995): Relative masses of primary 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.


van der Winden, J. (2005): Recording arrested primary moult in terns, using Black Terns Chlidonias niger as examples. Atl. Seabirds 7: 23 - 30.

This paper presents some adaptations to usual primary moult scores in terns. It is proposed to score old 'arrested' moult series separately, to facilitate the analysis of moult in the breeding period more effectively. To do this in a comparable manner, it is proposed to record moult scores for active series (after breeding) as A = new first series, B = new second series and C is new third series. For old (arrested) primaries this can be expanded to: E = old first series, F = old second series and G = old third series. Some examples for Black Tern are presented for the whole annual cycle.

Verbeek, N. A. M. (1977): Timing of primary moult in adult Herring Gulls and Lesser Black-backed Gulls. J. Orn. 118: 87 - 92.

Timing of primary moult in relation to the breeding cycle is presented for 113 actively moulting adult Herring Gulls and 79 Lesser Black-backed Gulls from Walney Island, England. Moult in both species occurred about when the eggs hatched in mid-May. The entire Herring Gull population began to moult the primaries within a period of 50 days. Lesser Black-backed Gulls started to moult 10 days later than Herring Gulls but many birds were not yet moulting as late as 5 August when I left the study area. It is suggested that the population of Lesser Black-backed Gulls consists of residents and migrants and that the former begin to moult earlier than the latter.

Verheyen, R. (1950): La mue du Coucou d'Europe Cuculus c. canorus L.. Gerfaut 40: 212 - 231.

(translation from French) 1. The Cuckoo has one single complete moult per year. It starts by shedding a central rectrix and a couple of tertials in the wing, and ends with the competion of central (medianes) secondaries.
In some juveniles the moult starts already in Europe by the second half of July (cf Stresemann 1920; Clancey 1948); it may continue on migration (probably unsubstantiated; CP), finally being completed in winter quarters, with the exception of a few central secondaries and their coverts, the moult of which is suspended. This facilitates age-determination of birds in their second calendar year (cf. Stresemann 1920; Witherby 1946) and shows that the reddish variant in females is a stable phenomenon (cf. Stresemann 1920).
2. It seems as if not all males achieve sexual maturity in their second calendar year. In adults the reproductive period ends by 18 - 22 June in Belgium, and the first signs of moult can be observed by this time.
3. The plumage is replaced at a rather slow pace and normally terminated with breast feathers and with the fifth primary. Starting in Europe, on part of the adults in late June/early July, the moult normally seems to be finished in Africa by February or March, secondaries being the last to be replaced.
In normal cases a whole year is therefore needed in order to follow the sequence of complete moult. The major part is performed during the course of eight or nine months, however. Replacement of coverts, remex and rectricies may take place simultaneously.
A. The moult of each half of the tail starts with the shedding of the central one (1), and continues 5 - 3 - 2 - 4.
B. Primary moult starts with the innermost (1), continuing 9 - 7 - 5 - 3, and simultaneously there is a second series: 4 - 2 - 10 - 8 - 6.(...)
The exchange of rectrices may proceed synchronously in both halves of the tail and in both wings, but according to the material available, this symmetrical moult doesn't seem to occur commonly. The exchange of feathers is often more advanced on the left side (less common on the right side), and the opposite side lags a little behind. In most cases the difference in time doesn't exceed the time necessary to complete a remige. As a result the two parts of tail and the two wings may have remex growing alternatively, but with the same pattern in each wing treated in isolation (while the two series proceed independently of each other). In a few cases this retardation may affect two or even three remex.
5. When the Cuckoo is moulting in a normal way, the flying ability of the bird is at no point impaired. The tail, as a matter of fact, comprises at least eight rectrices (nine if they are exchanged alternatively) and each wing contain at least sixteen functional remex (nineteen or eighteen if the succession of the four zones is altertating or consecutive).
We assume that the particular mode of renewal of flight-feathers, which can be seen in the Cuckoo, allows the bird to retain a fairly intact plumage throughout the year, and to keep up with its preferred prey, that may be abundant only at times and locally.
6. Measurements have shown that young birds have shorter wings than adults (cf. Stresemann 1920), and that the ratio between male and female wing-lengths is constant, also in juveniles. Furthermore it seems as if females by the end of the egg-laying period are carrying a substantial weight.
7. In African and Asian cuckoos belonging to genera Cuculus, Pachycoccyx and Chrysococcyx the moult of tail-feathers and remex proceeds accoprding to the same pattern as in Cuculus canorus.

Vikberg, P. (1974): Moulting records at Signilskär in the early autumns of 1971-72. Lintumies 9: 57 - 61.

Village, A., M. Marquiss & D. C. Cook (1980): Moult, ageing and sexing of Kestrels. Ring. & Migr. 3: 53 - 59.


Walters, J. (1978): The primary moult in four gull species near Amsterdam. Ardea 66: 32 - 47.

In the Amsterdam-Zandvoort area in the Netherlands in 1976 and 1977 a study was conducted on the primary moult in Black-headed, Common, Herring and Great Black-backed Gulls. Two methods were used: registration of primary moult score in recently dead gulls and collection of newly shed primaries. Special attention was paid to the identification of the primaries. A detailed description of the timing of the timing of the primary moult in adults and sub-adults is given. The average duration of the primary moult was 3 months in adult Black-headed, 4 1/2 months in adult Common and 6 months in adult Herring Gulls. Sub-adults were earlier and had a shorter moulting period: 2 1/2 months in Black-headed and 4 1/2 months in Herring Gull. The onset of the primary moult was not known for the Great Black-backed Gull, not breeding in the Dutch area, for the other three species earliest in the Herring Gull, slightly later in Common Gull and latest in Black-headed Gull. Practically all adult Herring Gulls started primary moult during the incubation of the eggs, much fewer adult Common and practically no adult Black-headed Gull did so. The finish of the primary moult was earliest in adult Black-headed, slightly later in adult Common, still later in adult Herring and latest in adult Great Black-backed Gull (until early January by the latest).(...)

Walters, J. (1979): The onset of the postnuptial moult in the Common Tern Sterna hirundo near Amsterdam. Ardea 67: 62 - 67.

A study of the onset of the moult of remiges and rectrices in the Common Tern was conducted near Amsterdam in 1977 and 1978. Two methods were used: registration of primary and rectrix moult scores in breeding birds and collection of newly shed feathers. Special attention was paid to the identification of the feathers collected. The conclusions on the onset of moult in this species in Stresemann & Stresemann (1966) are generally confirmed and the following more precise and additional data could be obtained.
The primary moult started with P1 on 3 - 6 July, followed by the first P2 on 6 - 10 July. The first P3 were recorded 10 - 15 July, the first P4 18 - 22 July and the first P5 on 31 July. No P6 was found, but the numbers of terns still present in August were low. A few outermost secondaries were recorded from 17 and 18 July onwards. The moult of the rectrices started just before the primary moult in early July. On average - but with exceptions - the order of moult was R1, R2, R3, R6, R4 and R5. The first R6, R4 and R5 were collected in the second week of July.
The majority of Common Terns started to moult after the fledging of their young or after unsuccessful breeding, but in July 20 % of the late breeders had beginning moult in the primaries and as many as 71 % had started tail-moult.

Walters, J. (1987): Primary moult in Black terns and Common Terns. Ring. & Migr. 8: 83 - 90.

In July-September 1984 the primary moult of Black Terns Chlidonias niger and Common Terns Sterna hirundo was studied in the southwestern region of the Ijsselmeer near Amsterdam, The Netherlands. The study was undertaken using the method of collecting and identifying shed primaries. Primaries collected were identified by their length.
Both species have a similar timing and speed of the postnuptial primary moult. In the second half of August the progress of this moult, expressed in the unit "average primary per collecting date" slows down gradually to practically nil by mid September. It is shown that this is caused by earlier departure of more advanced moulters out of the area, whereas less advanced moulters continue to contribute to the overall moult pattern.
The stages at which the birds arrest the prenuptial primary moult (second series; CP), as reflected by shed primaries collected, are compared with data in the literature and from personal observations on whole wings. The differences found between the two groups point out that birds arresting prenuptial moult in an earlier stage appear to suspend postnuptial primary moult earlier than more advanced prenuptial moulters.

Ward, R. M. (2000): Migration patterns and moult of Common Terns Sterna hirundo and Sandwich Terns Sterna sandvicensis using Teesmouth in late summer. Ringing & Migration 20: 19 - 28.

Watson, G. (1977): The mechanism of feather replacement during natural molt. The Auk 80: 486 - 495.

1. Observations of feather replacement in live and preserved specimens of several species of birds during natural molt demonstrate that old feathers are actively pushed out of the follicles attached to the tips of the sheaths of the incoming feathers. 2. There may be a constriction at the zone of juncture but the outer layer of the calamus of the old feather and the sheath of the new feather are apparently continuous. 3. The old feathers are broken off when the new feather sheath becomes keratinized. 4. The physical connection is still present when growth is renewed in a papilla which has been dormant 10 months. 5. This mechanism of feather replacement has been observed in eight diverse orders of birds. 6. Molt consequently appears to be a single growth process actively concerned only with the new generation of feathers. The old generation is passively shed. 7. Molt nomenclature should reflect this natural relationship between the growth process and the generation of feathers it produces.

Weitnauer, E. (1977): Von der Mauser der Handschwingen beim Mauersegler Apus apus. Orn. Beob. 74: 89 - 94.

Westphal, D. (1976): Über die postjuvenile Mauser beim Grünfink (Carduelis chloris.) J. Orn. 117: 70 - 74.

In 133 first year Greenfinches the moult of the flight feathers and the upper greater primary and secondary coverts were examined. The birds have been divided in the following groups:
a) Immatures that moult none of the primaries, secondaries and rectrices.
b) Immatures that moult all or some rectrices and/or tertials but fail to moult the functional primaries 1 to 9 and secondaries 1 to 6.
c) Immatures that moult some or all functional primaries 1 to 9 and secondaries 1 to 6 - besides as a rule all tertials and rectrices were new. 10 % of the juvenile birds examined between July and December 1974 showed this kind of moult.
The great variability in the postjuvenile moult of the Greenfinch is compared with four other species which are known to have the same kind of moult. The postjuvenile moult is likely to depend on duration and situation of the breeding season.

Williams, E. V.& J. P. Swaddle (2003): Moult, flight performance and wingbeat kinematics during take-off in European starlings Sturnus vulgaris. J. Av. Biol. 34: 371-378.

The effects of natural moult on avian flight performance have received relatively little attention, yet moult is an important part of the annual cycle. Quantification of flight costs will help to explain the diversity of moult patterns observed in avian taxa. Take-off from the ground requires a high power output from the flight muscles compared to other modes of flight, and is an important feature of foraging and predation escape. The present study was designed to quantify the effect of natural moult and new plumage on the take-off strategy, kinematics, and flight performance of European starlings Sturnus vulgaris. A high-speed (185 Hz) cine camera was used to film seven European Starlings on three occasions: session 1, two weeks prior to the onset of moult; session 2, during mid-moult; and session 3, two weeks after full plumage had re-grown. From subsequent film analysis, we assessed take-off speed and angle, the energy gained per wingbeat, and wingtip kinematics. Take-off strategy (note the inflation of words; trade-offs and now take-offs. CP) (measured by angle and speed) altered through the course of the three experimental sessions, i.e. ascent angle decreased and take-off speed increased. Energy gained per wingbeat did not vary, suggesting there was no significant decrease in flight performance due to moult, but there was a significant improvement in take-off performance due to renewal of flight plumage. Wingbeat amplitude increased in association with moult and after flight plumage had been completely renewed. The European starlings incurred relatively minor flight costs due to moult, when comparing before-moult with during-moult take-off performance. The apparent absence of additional flight costs associated with moult may reflect a decreased mechanical performance of year-old feathers (which are replaced during the moult) and may also help to explain the relatively long duration of the moult in this species. This study also provides evidence of the benefits of plumage renewal, as take-off performance is improved after moult has been completed.

Williamson, K. (1957): Post-breeding moult of Crossbills. Scott. Nat. 69: 190 - 192.

Williamson, K. (1957): The annual post-nuptial moult in the Wheatear (Oenanthe oenanthe.) Bird Banding 28: 129 - 135.

The progress of the complete post-nuptial molt in the Wheatear (Oenanthe oenanthe) is described from examination of over 80 specimens trapped at Fair Isle Bird Observatory.
Molt commences in late June, unless delayed by late nesting, and occupies 7-8 weeks, finishing in the third week of August. Juveniles molt the contour feathers, median and occasionally some greater and lesser coverts when between 5-8 weeks old.
Wing and tail molt are very severe in the early stages, and the birds inactive. The few weight records from "repeat" trappings suggest a gain on normal weight at the onset and a slight loss towards the end of the period.
The severity of wing and tail molt restricts the Wheatear to a single brood at Fair Isle and farther north (Faeroe Islands, Iceland. Greenland).

Williamson, K. (1961): Sequence of the post-nuptial moult in the Starling. Bird Migr. 2: 43 - 45.

Williamson, K. (1962): Post-nuptial moult in the Dunnock. Bird Migr. 2: 114 - 115.

Williamson, K. (1965): Moult and its relation to taxonomy in Rock and Water Pipits. Br. Birds 58: 493 - 504.

Wilson, J. R. & R. I. G. Morrison (1981): Primary moult in Oystercatchers in Iceland. Orn. Scand. 12: 211 - 215.

Immature Oystercatchers moulted from the end of May to September, and adults from late July or early August to October. Both age groups completed moult in about 100 days. Adults began moulting as soon as their young had fledged. Adults decreased in weight during the first half of moult; immatures increased in weight during the second half. The south-west is the main moulting and wintering area within Iceland. This is probably because of the relatively mild climate and the presence of large mussel stocks. Many birds from South Iceland, where there are no large coastal feeding areas, moult in winter quarters in the British Isles. The situation on other coasts is obscure.

Winkler, R. (1975): Mauserverhältnisse bei Rauch- und Mehlschwalben auf dem Herbstzug. Orn. Beob. 72: 119 - 120.

Winkler, R. (1987): [Wing and tail moult in young cormorants Phalacrocorax carbo sinensis.] Orn. Beob. 84: 317 - 323.

Winkler, R. & L. Jenni (1987): Weitere Indizien für "sektorale" Handschwingenmauser bei jungen Singvögeln. J. Orn. 128: 243 - 246.


Zeidler, K. (1966): Untersuchungen über Flügelbefiederung und Mauser des Haussperlings (Passer domesticus L.). J. Orn. 107: 113 - 153.

(Transl.; the area of investigation was Potsdam, Berlin) 1. The sequence of remige and body moult was investigated in Passer domesticus. The material comprised 126 moulting birds. Furthermore the daily growth rate of remiges was studied on 78 caged birds.
2. a) P10 is longer in juveniles than in adults. Its great upper covert is reduced in both age classes, but not entirely lost. b) Each secondary is connected with a sequence of downy feathers, that may be interpreted as remnants of the small upper secondary coverts. c) The great lower secondary coverts are strongly reduced; in many individuals they lack altogether.
3. Moult. Adult House Sparrows start moulting from the end of July to early August, juveniles from early broods already in late May. Moult will last on average 82 days in adults, in one case only 66 days. Juveniles from late broods moult faster. The last moulters finish by mid-October.
Primaries are shed in descendant sequence, outer secondaries (1-6) in ascendant sequence. Before the outer secondaries are shed the three tertials (A7 - 9) are renewed, starting with the middle one, A8.
The three feathers of the alula are shed in descendant sequence in the last fourth of the moulting period.
In the general renewal of wing feathering covering and covered feathers are related to each other. Growing feathers are protected by already grown as much as possible.
The feather called "10 great upper secondary covert" by some authors is not renewed simultaneously with the upper secondary coverts proper, on the other hand the carpal covert is moulted at the same time as these latter.
Median primary coverts are moulted descendantly, median secondary coverts ascendantly.
Edge feathers are moulted shortly after moult start, upper arm feathers and scapulars not until the end.
Rectrices are renewed in centrifugal order after P5 has been shed. Upper and lower tail coverts are renewed at such an early state, that they are able to cover the pins of growing rectrices. (...)

Zenatello M., Serra L. & Baccetti N. (2002): Trade-offs among body mass and primary moult patterns in migrating Black Terns Chlidonias niger. Ardea 90: 411 - 420.


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