Flightlessness in Some Moulting Passerines in Northern Europe

Flightlessness in some moulting passerines in Northern Europe

ERKKI HAUKIOJA Department of Zoology, University of Turku

HAUKIOJA, E. [Zool. Dept., Univ. of Turku, SF-20500 Turku 50, Finland] 1971. - Flightlessness in some moulting passerines in Northern Europe. Ornis Fenn. 48 :101-116. The effects of wing and tail moult on flying ability have been evaluated for four passerine species (Luscinia svecica, Phylloscopus trochilus, Motacilla flava, M. alha) in Finnish Lapland and Sylvia communis in southern Finland. All species have a short postnuptial moult (between 35 and 50 days) and in Luscinia svecica, Phylloscopus trochilus and Sylvia communis some moulting specimens unable and/or unwilling to fly have been caught. The stage of the moult affects the probability of a bird being caught so that birds which are at the peak of their moult are more difficult to catch with nets. The phenomenon of flightlessness is therefore obviously more common than can be evaluated from moult card data. Flightlessness depends on the fact that not only are many wingfeathers lost simultaneously but also that in Luscinia svecica, and to a lesser extent in Phylloscopus trochilus, tail feathers are lost simultaneously. The tail moult is most intense during a phase when there are not very large gaps in the wings : this helps in part to maintain as high a degree as possible of flying ability. Wagtails (open field species) can avoid flightlessness, in spite of a short moult, by a prolonged tail moult.

Introduction The phenomenon that flight feathers are (1968, 1972) added the following spe- simultaneously shed in waterfowl, thus cies: the Willow Warbler Phylloscopus causing temporary flightlessness, is well trochilus and the Whitethroat Sylvia known. The same tendency has also been communis. HAUKIOJA (1971a) men- verified in certain other groups of water- tions that perhaps also the Bluethroat birds (SALOMONSEN 1968) . There are Luscinia svecica and the Redwing Turdus scattered data in literature showing that iliacus belong to those species which some passerines may be completely or lose or may lose their ability to fly nearly flightless during the most intense during the moult. Reduced numbers of shedding of flight feathers. BALÅT caught birds during the postnuptial (1960) and SULLIVAN (1965) have moult eg. the Bullfinch Pyrrhula found that Dippers (Cinclus cinclus and pyrrhula (NEWTON 1966) and the C. mexicanus) were unable to fly during Chaffinch Fringilla coelebs (DOLNIK & the wing moult. STRESEMANN & STRESE- BLUYMENTAL 1967) are a possible MANN (1966) cited two cases from indicator of reluctance to fly. In these Arctic regions concerning the Snow species, however, the ability to fly is Bunting Plectrophenax nivalis and the probably not threatened. Lapland Bunting Calcarius lapponicus. The aim of the present paper is to BERGER (1967) mentions that at least investigate the occurrence of flightless- some Thrush Nightingales Luscinia ness in some passerines and to try to luscinia lose their ability to fly during find out what events in renewal of the moult. HAUKIOJA & KALINAINEN feathers cause this phenomenon, and how it can be overcome by some species.

102 ORNIs FENNICA Vol. 48, 1971

Materials and methods TABLE 1. Rate, duration and time of the postnuptial moult in the Willow Warbler There is a general tendency for small, insect- Phylloscopus trochilus in the Kevo area, Fin- eating passerines to moult faster than larger, nish Lapland. seed-eating species. In those species that moult ADULTS after breeding the farther north (in the AGE BOTH northern hemisphere) they live, the faster SEX their moult tends to be. Therefore, the most YEAR 1971 intense moult and, accordingly, the most LOCALITY during the LATIT . 68 - 70 N probable loss of the ability to fly 26 - 28 E moult, probably occurs in small insect-eating LONG . FIRST BIRD EXAMINED (DATE) 2 . 7 . passerines at the northern limits of their 7 . FIRST BIRD IN MOULT EXAMINED IDATLI 4. distribution . Materials analysed in this paper 27 . 8. Kevo LAST BIRD IN MUULT EXAMINEU IDATEI refer therefore to four species from the 27 . 8. area (ca 69.5°N, 27°E), Finnish Lapland. In LAST BIRD EXAMINED (DATE) basis SAMPLE SILE (TOTAL) 131 addition, the Whitethroat, which on the 90 (HAUKIOJA & KALINAINEN SAMPLE SIZE (MOULTING) of earlier results n 1972) would to be one of the southern Finnish REGRESSION EQUATION X 8.2 .0 .97Y species most likely to be unable to fly when )EQUATION COMPUTED AS REGRESSION X ON Y) LINEARITY TEST moulting, has been taken into account. F 1 32 F 2 56 The materials from Lapland have been F 3.12 collected largely in studying the late summer DAILY INCREASE OF MOULT SCORE ecology of subarctic passerines in 1970 and REGRESSION EQUATION 1.04 FROM 0.044 E 90 1971. The periods of field work at Kevo N Subarctic Research Station were 16 July-18 1.14 FROM RECAPTURES 0.046 E 6 August, 1970 and 3 July-27 August, and N 15-19 September, 1971 . Materials from START OF MOULT 9. 7. southern Finland have been collected in SPREAD (DAYS) 22 other studies and as a result 95 PER CENT connection with END OF MOULT 21 . 8. (HAUKIOJA of a moult inquiry 1971b) . DURATION OF MOULT (DAYS) The normal sequence of the moult in the FROM REGRESSION EQUATION 43 passerines dealt with here is the same as given FROM RECAPTURES 39 by DWIGHT (1900) . The moult starts with the shedding of the innermost primary and ends with the growth of the outermost primary or the innermost secondary. For each species dealt with here, data are provided for the duration and time of the E. Haukioja: Flightlessness in moulting passerines 103 postnuptial moult, which, as is common Warblers in the Kevo area probably have as practice, has been calculated from primary long a moult as in southern Finland . In 1971 scores (0 for an old wing and 45 for a new rather reliable material was gathered at Kevo wing; for discussion of the method see EVANS and, according to this (Fig . 1, Table 1), the (1966) . Other details of the moult, which are duration of the moult was about 40 days . needed especially when discussing reduced flying ability, are the secondary score (from Motacilla alba 0 to 30), raggedness of wing (rising from 0 and then falling back to 0), tail score (from The primary scores of White Wagtails caught 0 to 30) and raggedness of tail (rising from at Kevo in 1970 and 1971 are presented in 0 and then falling to 0) . Information on Fig. 2 and the summary of the moult in Table calculating raggedness values is given in HAU- 2. The duration of the moult, 45-50 days, is KIOJA (1971b) and others eg. in EVANS considerably shorter than that recorded in a (1966) . sedentary population of Pied Wagtails Mota- The data have been processed using prog- cilla alba yarrellii in England (76 days, rammes devised for treating moult-inquiry BAGGOTT 1970) . This is probably the only data (HAUKIOJA 1971b) . clear-cut case where a difference between populations of the same species has been verified . Time and duration of the post-nuptial moult Motacilla flava HAUKIOJA & KALINAINEN (1971) give the In the following, data of the moult of duration of the Yellow Wagtail's moult in common, insectivorous passerines in the southern Finland as roughly 40 days . Only 22 Kevo area are presented ; moulting specimens were studied in the Kevo however, the area and all that can Redstart Phoenicurus phoenicurus and be said of them is that the Pied Flycatcher Ficedula hypoleuca, of which too few have been examined, TABLE 2 . Rate, duration and time of the are excluded postnuptial moult in the White Wagtail Mota- . As a background to these cilla alba in the Kevo area, Finnish Lapland data it may be mentioned that a moult- in 1970-1971 . ing period shorter than 35-40 days is uncommon in passerines. AGE ADULTS SEX BOTH Luscinia svecica YEAR ALL LOCALITY LATIT. 68 - 70 N HAUKIOJA (1971a) gave the duration of the LONG . 26 - 28 E postnuptial moult in the Bluethroat as 38-40 FIRST BIRO EXAMINED (DATE) 4. 7 . days in 1970. More material gathered at Kevo FIRST BIRD IN MOULT EXAMINED (DATE) 4. 7. in 1971 indicated a somewhat longer moult LAST BIRD IN MOULT EXAMINED (DATE) 17 . 8. (42-45 days) . The mean date for the start LAST BIRD EXAMINED (DATE) l7 . 8 . of the moult is the middle of July and for SAMPLE SIZE (TOTAL) 39 the completion of the moult the latter half of SAMPLE SIZE (MOULTING) 35 August. REGRESSION EQUATION Y= -4 .9s0 .94X (PERIOD USED IN COMPUTATION 12 . 7.-17 . 8 .) Phylloscopus trochilus LINEARITY TEST F 1 19 F 2 10 Although the Willow Warbler has ten visible F 0.64 primaries, the computations have been carried DAILY INCREASE OF MOULT SCORE out using only the FROM REGRESSION EQUATION 0.94 nine innermost ones. This SE 0.115 is reasonable because the ninth, long primary N 31 completes growing FROM RECAPTURES after the tenth, short 0.059 primary, although they are shed in the nor- N 3 mal order. START OF MOULT 8. 7. HAUKIOJA & KALINAINEN (1968) give 37 95 PER CENT SPREAD (DAYS) 26 days (or an even shorter time according to a END OF MOULT 25 . 8. few recaptures) for the duration of the wing DURATION OF MOULT (DAYS) moult in the Willow Warbler in southern FROM REGRESSION EQUATION 48 FROM RECAPTURES 46 Finland . HAUKIOJA (1971a) states that Willow

104 ORNIs FENNICA Vol. 48, 1971

they moult from the June-July to the middle during the short summer is probably a of August. Thus they complete their moult before the White Wagtail in the same area. compromise between all phases. This results in a solution where breeding and Sylvia communis moulting overlap to a much greater extent than in more southern populations HAUKIOJA & KALINAINEN (1968) give 40 (HAUKIOJA 1971a) . Because the moult days as a rough estimate of the duration of the moult in the Whitethroat. A larger number of cards (including the above data) gathered in TABLE 3. Rate, duration and time of the 1968-1970 (Fig. 3, Table 3) give the same postnuptial moult in the Whitethroat Sylvia estimate as regards to the length of the moult. communis in southern Finland in 1968-1970. (HAUKIOJA As has been explained elsewhere AGE ADULTS & KALINAINEN 1972), the Whitethroat is SEX BOTH rather erratic in the manner in which it begins YEAR ALL and passes through its secondary moult. LOCALITY ALL Secondary moult often begins earlier in rela- FIRST BIRD EXAMINED (DATE) 1 . 7. tion to the primary moult than in other FIRST BIRD IN MOULT EXAMINED (DATE) 8. 7. passerines . It may start, besides from the first (outermost) secondary also from another point, LAST BIRD IN MOULT EXAMINED (DATE) 29 . 8. usually from the sixth (innermost) secondary. LAST BIRD EXAMINED (DATE) 29 . 8. SAMPLE SIZE (TOTAL) 89 SAMPLE SIZE (MOULTING) 79 These species all have a rather short REGRESSION EQUATION X x16.0+0-.81Y and intense moult and they live in an (EQUATION COMPUTED AS REGRESSION X ON Y) LINEARITY TEST environment where time is rather short F 1 29 F 48 for completing the summer schedule. F 2 1.27 This includes at least the following DAILY INCREASE OF MOULT SCORE FROM REGRESSION EQUAI1ON 0.92 phases: breeding, moult, pre-migratory SE 0.082 N 79 fatdeposition and migration . The above FROM RECAPTURES 1.04 SE 0.154 phases are such that there is evidently N 14 only small possibility of reducing their START OF MOULT 15 . 7 . length although a population lives at the 95 PER CENT SPREAD (DAYS) 28 END OF MOULT 21 . 8. limits of the distribution area of the DURATION CF MOULT (GAYS) species. The way in which it is possible FROM REGRESSION EQUATION 37 to complete the whole summer cycle FROM RECAPTURES 43 E. Haukioja: Flightlessness in moulting passerines 105

is, at least in most cases, as long in secondaries does not usually start at this Lapland as in southern Finland, I have phase (Figs. 9-13) . As those primaries also used materials originating from which have fallen earlier grow and the other parts of Finland for those species following primaries are lost more slowly, (the White and Yellow Wagtail) where the raggedness values fall until the be- the numbers caught at Kevo are rather ginning of secondary moult. At this small. Data for secondary and tail scores phase birds have two moulting centres and raggedness values have been gath- per wing at the same time. Raggedness ered from the following areas: values rise again and usually reach their Bluethroat, years 1970-1971, Finnish Lap- peak between primary stages 25-40 . land. Willow Warbler, years 1970-1971, Then raggedness values fall again as the Finnish Lapland. White Wagtail, years 1970- moult nears its completion. 1971, Finnish Lapland and years 1969-1970, In order to compare the raggedness different parts of Finland. Yellow Wagtail, years 1970-1971, Finnish Lapland and years of wing in different species, and also to 1969-1970, different parts of Finland. White- a certain degree, the ability to fly, I have throat, years 1968-1970, southern parts (60°- calculated the mean raggedness values 64°N) of Finland. during primary scores 30-39 for each species (Table 4) . This phase of the Flying ability and moult moult, also used by HAUKIOJA & KA- LINAINEN (1972), was chosen arbi- In order to test the reduction in the trarily but it is useful because in most flying surface of wings, the raggedness species it covers the phase when points values were plotted against the date (Figs. 4-8) . TABLE 4. Mean raggedness of wing during All these figures have the same basic moult stages 30-39 in five passerines. form; two peaks with the intervening Raggedness of wing valley occurring between or near primary Species scores 15-20. The steep rise in ragged- Mean SE N ness values in the first stages of primary moult reflects the fact that in the species Luscinia svecica 19.8 1.06 9 Phyllosc. troch. 17.6 1.38 11 dealt with, the first primaries (five or Motacilla alba 13.7 1.00 12 fewer) fall in swift succession or, often, M. flava 16.8 0.42 43 almost simultaneously . The shedding of Sylvia communis 21.5 2.92 6 106 ORNIS FENNICA VOl. 48, 1971 E. Haukioja: Flightlessness in moulting passerines 10 7

FIGS. 4-8 . Raggedness of wing in relation to primary scores in five passerines .

on the raggedness curve are at a high There are field observations of the first level for the second time, and ends three species showing that, while evi- before the final decline . In most cases dently not injured in any way, the birds the secondary moult is also in good did not start to fly when released in an progress but has not come to an end open field but escaped by running. Un- (Figs. 9-13) . According to Table 4 the fortunately these cases have not been wings of species dealt with can be put recorded systematically, but there are to the following order from the most more than ten such cases among the ragged to the least ragged: Whitethroat, materials presented here. Raggedness Bluethroat, Willow Warbler, Yellow values of these birds were in most cases Wagtail, and White Wagtail. near 25. ORNIS FENNICA VOI. 48, 1971 E. Haukioja: Flightlessness in moulting passerines 109

PRIMARY SCORE

FIGS. 9-13 . Secondary scores in relation to primary scores in five passerines .

From the above data it seems evident In order to determine whether and that rather few birds actually lose their to what degree moulting affects the ability to fly when moulting even among probability of a bird's being caught, I those species selected here. However, constructed Fig. 14 where mean catches great bias may exist in the fact that all of adult Bluethroats and Willow birds caught for moult examinations Warblers in 1971 at Kevo have been were caught using mist-nets and it is plotted against the date (and against obvious that those individuals that lose primary scores of the population) . their ability to fly totally, are rather Both species are caught rather effec- difficult to get into nets which are tively in relation to catching effort on constructed primarily in order to catch the first half of July (the peak in flying individuals . catches probably indicates the phase ORNIs FENNICA Vol. 48, 1971

FIG. 14 . Numbers of adult Bluethroats and Willow Warblers caught/100 netting hours at Kevo, Finnish Lapland in July-August 1971 . when birds relax from breeding activities nomenon occurs also in southern Fin- and begin to stray more) . In the latter land ; where there is some evidence that half of July catches in relation to the the numbers of eg. Willow Warblers catching efficiency suddenly drop for rise again at the end of the moult, both species and remain at a low and although the situation is a little compli- rather stable level up to the phase when cated (HAUKIOJA & KALINAINEN birds complete their moult and leave 1972) . the area evidently just after completion 2 . Birds may have started migration the moult . during the moult. This is, however, Thus the phase of the moult affects improbable (see HAUKIOJA 1971a) . to likelihood of the birds' being caught 3. Birds may have moved to a safer rather a lot . This indicates that birds biotope, eg. to thickets . This also is an are less active when moulting and are improbable explanation because netting more often unable to fly than seems to was carried out in one of the most be the case when the numbers found luxuriant parts in the whole Kevo area. among netted birds are examined. The following possible sources of error have, In the following I discuss factors however, to be taken into account : other than raggedness of the wing which 1 . Birds may have suffered from a may affect to the ability to fly during high mortality during the moult; this the moult and compare the species would cause late summer numbers to be treated in this paper . rather low. As this decrease in numbers The time when the numbers in catches also occurred in 1970, however, it is decrease markedly (Fig. 14) falls near improbable that this 2/3 decrease was the primary score of 15 in the Willow due to mortality . This kind of phe- Warbler and a little earlier in the Blue- E. Haukioja: Flightlessness in moulting passerines throat . Raggedness values are not very tail moult (see also BAGGOTT 1970) . high at this phase but Figs. 15 and 16 Because the tail moult is more asynchro- show that the tail moult for both species nous in wagtails than in passerines in has entered its first stages . For Fig. 20 general and is also rather prolonged 1 calculated the mean numbers of grow- (Figs. 17 and 18), rather good steering ing tail feathers and raggedness of the ability is probably maintained the whole tail in relation to the primary score for time. The White Wagtail was earlier each species. In the Bluethroat and the mentioned as having a more long moult Willow Warbler tail feathers are shed than the Yellow Wagtail and, conse- almost simultaneously and consequently quently, it has lower raggedness values their tail raggedness rises to a very high for the tail than the Yellow Wagtail . level. In the Bluethroat the tail moult This depends largely on the fact that the is more intense and occurs a little earlier Yellow Wagtail has more tail feathers in relation to the primary moult than growing simultaneously, which is the in the Willow Warbler. It therefore usual way of achieving a quick moult coincides well with the situation shown (eg. BERTHOLD et al. 1970) . in Fig. 14. Decreased activity occurs at The fifth species, the Whitethroat, the time when the tail is lost. However, differs from the above species because activity remains at a low level even the way in which it begins its moult during the phase when the tail has again varies (HAUKIOJA & KALINAINEN reached nearly full length. As was shown 1972) . Because the tail moult may start earlier, the raggedness curve generally early and end late (even before or after has two peaks, and in the Willow the moult of the primaries) a rather low Warbler the tail moult is most intense course in the raggedness values of the between these peaks. This evidently tail is arrived at in spite of a rather fast means that the ability to fly is maintained moult. Consequently, flightlessness in at as high a level as possible the whole the Whitethroat depends mainly on the time . In the Bluethroat smaller materials high raggedness values for the wings. indicate that the first peak of wing raggedness (if it can be distinguished at all) and the peak of tail raggedness Discussion coincide. It is not quite so simple to evaluate effects on the ability to fly as It is clear that in some northern the Bluethroat has a slightly longer passerines some individuals at least lose moult and does not seem to shed more their ability to fly during the moult. In than four primaries at a time while the fact this possibility can be refuted only Willow Warbler often sheds five. In the in rather few insectivorous passerines in Bluethroat the tail is again in rather northern Europe. Flightlessness is prob- good condition (especially as regards ably more common than can be estimated width, see EVANS 1966, p. 199) when from the mere numbers of birds caught the raggedness values of the wing reach for moult examination and evidently the second peak. much more common than can be argued When compared with other species in from visual observations in the field. In Fig. 20, wagtails, which are open field most cases the first indication may be species, begin their tail moult at the that moulting adults are difficult to find same phase as the two former species, with or without nets, but this does not but the tail moult continues longer than necessarily prove anything more than in these species and thus makes possible that the activity of moulting birds longer and more slow progress in the decreases or that they change their ORNIS FENNICA VOl. 48, 1971 E. Haukioia: Flightlessness in moulting passerines

biotope (see HAUKIOJA & KALINAINEN skulking behaviour . For species shedding 1972) ; they may, however, still be able wing and/or tail feathers faster than the to fly. Birds moulting slowly probably Bullfinch, which NEWTON (1966) in- do not lose the ability to fly at all. What vestigated, this is still more important. the critical limit in the duration of the Eg. the Willow Warbler in heavy moult moult is I do not know and, as shown flies fluttering and is evidently unable to in this paper, birds having a moult of change direction quickly. It is my sub- about the same duration (eg. the Willow jective opinion that it is easily caught Warbler and the Yellow Wagtail) may by predators at this stage when flying. well adapt to different situations. Another important point is that by NEWTON (1966) has mentioned that, decreasing their flying activity, skulking in order to avoid avian predators, birds birds probably save energy for feather in active wing moult have adopted synthesis and thermogenesis, demands I

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E. Haukioja: Flightlessness in moulting passerines

which increase considerably västäräkki) sekä pensaskertulla eteläsuoma- for both of laisten aineistojen perusteella . Kaikilla näillä during the moult (LUST ICK 1970) . lajeilla on hyvin nopea sulkasato (35:n ja 50:n The phenomenon that, at the height päivän välillä) ja eräitä rajusti sulkivia, lento- of the moult, birds moulting quickly are kyvyttömiä tai lentohaluttomia yksilöitä on caught less efficiently than at the be- saatu verkkopyynnin yhteydessä . Koska linnun sulkasadon vaihe vaikuttaa selvästi pyydyste- ginning or at the end of the moult, tyksi tulemisen todennäköisyyteen (kuva 14) means that in such species moult scores siten, että rajuimmassa sulkasadossa olevat lin- plotted against date probably are not nut eivät juuri lennä verkkoihin, lentokyvyttö- normally distributed . This might cause myys on todennäköisesti tavallisempaa kuin sulkasatokorttiaineistot osoittavat. difficulties in computing the duration of Lentämisen välttäminen riippuu, paitsi ra- the moult and especially its confidence justa siipisulkasadosta, myös siitä, että erityi- limits, but these difficulties may be sesti sinirinnalla ja vähemmässä määrin myös mean dates for pajulinnulla, kaikki pyrstösulat vaihdetaan sa- overcome eg. by using manaikaisesti . Pyrstösulkasato on voimakkaim- certain moult scores in computations millaan vaiheessa, jolloin siipien aukkoisuus ei (see FLEGG & COX 1969, HAUKIOJA ole kovin korkea . Tämä osoittaa pyrkimystä yl- 1971b) . läpitää ainakin vähäinen lentokyky läpi sulka- What inability or reluctance to fly sadon. Avoimilla mailla elävät västäräkit pys- tyvät lyhyehköstä sulkasadostaan huolimatta affect the ecology of birds is practically ylläpitämään melko hyvän lentokyvyn sulkasa- unknown . It may however, have some don aikana, mikä johtunee etupäässä pitkälle importance for survival during heavy ajalle jakautuvasta pyrstösulkasadosta . rain, etc., and requires more investi- gation than has been carried out hitherto . The same can be also said, however, for References most other ecological aspects of moulting. BAGGOTT, G. K. 1970 . The timing of the moults of the Pied Wagtail . Bird Study Acknowledgements 17:45-16 . BALnT, F. 1960 . A study of moulting in the I wish to thank Prof. Paavo Kallio, the head Dipper, Cinclus cinclus (L.) . Zool. Listy of the Kevo Subarctic Research Station, and 9:257-264 . the personnel of the station for pleasant BERGER, W. 1967. Die Mauser des Sprossers working conditions . Besides, I am most grateful (Luscinia luscinia L.) . J. Orn . 108 :320- to the following persons who have helped by 327. filling in moult cards used in this paper: Dahl- BERTHOLD, P., E. GWINNER & H. KLEIN qvist, M., Ferm, A., Hakala, J., Hakala, T., 1970. Vergleichende Untersuchung der Hakila, R., Hollsten, J., Hyytiä, K., Häkkinen, Jugendentwicklung eines ausgeprägten L, Jaakola, H., Kaakinen, K., Kalinainen, P., Zugvogels, Sylvia borin, and eines weniger Karhumäki, J., Karlsson, L., Karlsson, R., ausgeprägten Zugvogels, S. atricapilla . Die Kaukola, A ., Kivivuori, O., Kolunen, H., Lah- Vogelwarte 25 :297-331 . tonen, L, Lehikoinen, E., Lokki, J., Mikko- DOLNIK, V. R. & T. I. BLUYMENTAL 1967. nen, A. V., Myrsky, H., Mäkisalo, I., Niemelä, Autumnal premigratory and migratory P., Saarinen, S. I., Sihvo, Y., and Virtanen, J. periods in the Chaffinch (Fringilla coelebs coelebs) and some other temperate zone S e 1 o s t u s : Sulkasatokautisesta lentokyvyt- passerine birds. Condor 69 :435-468 . tömyydestä eriiillä pohjoiseurooppalaisilla var- DWIGHT, K. L. 1900. The sequence of plum- puslinnuilla . ages and moults of the Passerine birds of New York . Ann. New York Acad . Sci . Siipi- ja pyrstösulkasadon vaikutusta lentoky- 13 :73-360 . kyyn on selvitetty neljällä lappalaisella varpus- EVANS, P. R. 1966. Autumn movements, moult linnulla (sinirinta, pajulintu, keltavästäräkki ja and measurements of the Lesser Redpoll

FIG. 20. Raggedness of tail and numbers of growing tail feathers (in half a tail) in relation to primary scores in five passerines . a = Luscinia suecica, b = Phylloscopus trochilus, c = Motacilla alba, d = M. flava, and e = Sylvia communis. ORNIS FENNICA VOI. 48, 1971

Carduelis flammea cabaret. Ibis 108: 183- sulkasadosta . Porin Lintutiet. Yhd. Vuo- 216. sik. 2 :75-78. FLEGG, J. J. M. & C. J. COX 1969. The moult - 1972. Eräiden varpuslintujen sulkasato- of British Blue Tit and Great Tit popula- kauden ekologiaa. Porin Lintutiet. Yhd. tions. Bird Study 16:147-157. Vuosik. 3:5-16. HAUKIOJA, E. 1971a. Summer schedule of LUSTICK, S. 1970. Energy requirements of molt some subarctic passerine birds with refer- in cowbirds . Auk 87:742-746. ence to postnuptial moult. Rep. Kevo NEWTON, 1 . 1966. The moult of the bullfinch Subarctic Res. Stat. 7:60-69. Pyrrhula pyrrhula. Ibis 108:41-67. - 1971b. Processing moult card data with SALOMONSEN, F. 1968. The moult migration. reference to the Chaffinch Fringilla Wildfowl 19:5-24. coelebs. Ornis Fenn. 48:25-32 . STRESEMANN, E. & V. STRESEMANN 1966. Die HAUKIOJA, E. & P. KALINAINEN 1968 . Paju- Mauser der Vögel. J. Orn. Sonderheft 107: linnun (Phylloscopus trochilus), pensas- 1-445. kertun (Sylvia communis) ja niittykirvi SULLIVAN, J. O. 1965. "Flightlessness" in the sen (Anthus pratensis) postnuptiaalisesta Dipper. Condor 67 :535-536. Received November 1971 .