The Condor961959-912 0 The CooperOrnithological Society 1994

AGE DETERMINATION OF BREEDING SHOREBIRDS: QUANTIFICATION OF FEATHER WEAR IN THE LEKKING GREAT SNIPE ’

STEINARE ÐER Department of Zoology, Universityof Trondheim, N-7055 Dragvoll, Norway

JOHN ATLE ms Nonvegian Institutefor Nature Research(NINA), Tungasletta2, N-7005 Trondheim, Norway

PEDER FISKE Department of Zoology, Universityof Trondheim, N-7055 Dragvoll, Norway

Abstract. We develop a method of aging Great Snipe ( media) by quantifying primary feather wear. No reliable method has hitherto existed to separate young (first- summer, second calendar year) and old Great Snipe during the breeding season.We quan- tified primary wear of cut-off feather tips usinga binocular microscopeand scoredthe degree of wear on six variables. We found that primary wear separatedwell between young and old , whereas morphological variation did not. In a sample of 405 Great Snipes from Norway, 98.7% of the males of known age (74 old, 3 young) were correctly classifiedto age with discriminant analysis using primary feather wear. We review the potential use of primary feather wear to separate first-summer individuals from older individuals in 113 Nearctic and Palearctic shorebird () .We note that in the majority of species,differential primary wear is the only available aging method during the breeding season. Key words: Aging;primaryfeather wear; molt; lek mating system;morphology; Gallinago media.

INTRODUCTION as a key to separate first summer and older in- Information about the age of individuals, and dividuals during the breeding season (Prater et thus the ability to age individuals, is of great al. 1977) and may, in some species,be the only importance in studies of population dynamics, method available. However, no study has pro- natural and sexual selection, and the evolution vided estimatesof the successof age determining of life histories (Clutton-Brock 1988, SEther birds according to primary feather wear during 1990, Steams 1992). Many methods exist for age the breeding season(but see Schamel and Tracy determination of living birds (see Prater et al. 1988 who did not succeedin distinguishing year- 1977, Pyle et al. 1987, Svensson 1992). How- ling and older Phalaropus lobatus using primary ever, due to feather molt and other factors, these wear). Therefore, there is a need to evaluate the methods often cannot be used to age birds be- usefulness of this method. Indeed, few studies yond their first winter. Most birds replace pri- have tried to quantify feather wear at all (see mary feathersannually (but see Summers 1983), attempts for shorebirds in Sheldon et al. 1958, but the timing of replacement may differ between Clausager 1973, Taylor 1979, Holz 1987, Devort age groups. In most shorebirds (Charadri- 1989; for passerines in e.g., Willoughby 1986, iformes) breeding in the northern hemisphere, 199 1; and referencesfor other groups in Rogers adults molt primary feathers in fall or winter, 1990), and these attempts often only use a three whereas the juveniles of many species do not or four point scale (see Rogers 1990). renew their primaries until the following summer As part of a larger study on the biology of the (Prater et al. 1977, Prater 198 1, Cramp and Sim- lekking Great Snipe (Gallinago media), we need- mons 1983). Therefore, in many speciesof shore- ed information about the age of individuals. In birds, differential wear of primary feathersis used particular, we wanted to separate first summer (2y, alternate 1 plumage) and older (3~s) birds during the breeding season. During the fall, ju- I Received29 December1993. Accepted24 May venile Great Snipe may be distinguished from 1994. adults on the basis of color and pattern of wing-

[9591 960 S. A. SETHER, J. A. K.&L& AND P. FISKE coverts and tail-feathers (Prater et al. 1977, to the nearest 0.1 mm. Length of white on tail Cramp and Simmons 1983). These feathers are was measuredas “. . . the distance from the distal molted on the winter groundsand aging is thought end of the most distal dark spot on the right outer to be impossible after all juvenile wing-coverts tail feather to the tip of that feather . . .” (HS- are replaced in early spring (Cramp and Sim- glund et al. 1990b). In addition, the number of mons 1983). However, the juvenile primary tail feathers with more than 50% white was feathers are retained to be molted after the first counted (except in 1986). Measurements were breeding season(Prater et al. 1977). Adult Great taken by the same person in more than 90% of Snipes molt their primaries in fall and winter the cases.Birds known to be old (3y+) are those (Jackson 1919, Woodman 1944, Kozlova 1962 banded as full grown the year before or earlier [cited by Tuck 19721, Devort and Paloc 1992) whereas birds known to be young (2~) are those and thus have fresher primaries in spring than banded as downy the year before. do first summer (2~) snipes. First summer Great FEATHER WEAR Snipesmight therefore be expectedto show more primary feather wear and tear. In addition, age- Wear causesseveral structural changesin feath- related differences in the durability of feathers, ers (Burtt 1986). For a detailed quantification of as have been found in other shorebirds (Prater feather wear, we cut off about 1 cm of the left et al. 1977) may also cause more primary wear ninth primary feather tip (counted from inside) in young birds. of most birds caught in 1987-1990 and in 1992. The purpose of this study was to develop a All featherswere coded and randomly sorted be- method of aging Great Snipe during the breeding fore being analyzed by one of us who was un- season.We show that a simple quantification of aware of the age and sex of the birds involved, primary feather wear, using a binocular micro- using a binocular microscope (20-60 x magni- scope, separated young and old birds, whereas fication). Degree of wear was scored according variation in six morphological traits did not. By to a scale from 1 to 3 on three variables (barb simply looking at feathers, and noting wear on a wear, barbule wear and hook wear, seeFig. 1 and three point scale, a relatively large number of Table 1). This was done for both the inner and birds were not ageable.We discussthe usefulness outer web of the feather, giving a total of six wear of our method for other hard-to-age shorebirds, score variables for each feather. The total score and present a list of the molt pattern of immature was computed as the sum of the six scores.This Nearctic and Palearctic shorebirds, indicating in sum is hereafter referred to as “total wear score.” which speciesprimary wear can be used to age As wear progressedinwards from the outside, birds during the breeding season. only the edgeof the terminal 0.5 cm of the feather tip was examined for wear. METHODS To evaluate the visual impression of feather wear, we also subjectively assigned the age of STUDY AREA AND FIELD METHODS each feather tip as young (strong wear), inter- We caught Great Snipes with mist nets on their mediate (moderate wear) or old (little wear) sim- leks in Gav&lia near Kongsvoll(62”17’N, 9”36’E), ply by looking at individual feather-tips. This Dovreljell, mid-Norway in May-June 1986-l 992 was done by the same person who scoredfeather (see also Fiske et al. 1994). The 15 km2 study wear, and after all feathers had been scored. area is situated in the sub-alpine and low-alpine regions, from 1,000 to about 1,200 m altitude. STATISTICAL ANALYSIS AND MATERIAL Further descriptionof the study area can be found We analyzed age-relatedfeather wear by discrim- in Pedersen et al. (1983) and in Lofaldli et al. inant analysis,using feathersfrom birds of known (1992). Birds were banded and several morpho- age. We used both a stepwise and a direct, si- metric measures taken: length of bill, length of multaneous method of entering predictor vari- bill plus head (see Fig. 2b in Green 1980) wing ables in our multivariable discriminant analysis length, true tibio tarsuslength (Prater et al. 1977) model. The stepwisemethod of variable entering and length of white on tail. Wing length was mea- was based on maximization of the minimum sured as the maximum length (Svensson 1992) Mahalanobis distance (Dz) between groups.Vari- to the nearest 1.0 mm with a ruler. All other ables were here entered/removed in the model measurements were taken with a digital caliper, when their partial Fvalues were greater/lessthan AGING OF GREAT SNIPE BY FEATHER WEAR 961

’ ’ Rachis

FIGURE 1. Simplified structureof a Great Snipe primary feather tip.

1. We also analyzed age-related morphological sexual dimorphism in Great Snipes (Hoglund et differencesby stepwise and direct discriminant al. 199Ob),we analyzed morphologyofmales and analysis. To increasestatistical power in the dis- females separately. criminant models using morphology, we also Counting each individual once per year (1986- made analyseswith a larger sample of agedbirds. 1992), a total of 806 birds have been measured Here we included birds aged according to pri- (578 males, 224 females),involving 59 1 different mary wear using a conservative criterion. Birds individuals. A total of 405 feathers (300 males, with a total wear score of 9 or less were consid- 105 females) from 36 1 different individuals were ered old, whereas birds with a total wear score aged according to feather wear (1987-l 990 and of 14 or more were considered young (see RE- 1992). A larger number of featherswas collected, SULTS). Becausethere is a slight morphological but some of these were excluded from the anal-

TABLE 1. Criteria used to scoreprimary featherwear. Each featherwas scored1 (no wear), 2 (moderatewear) or 3 (strongwear) accordingto the criteria in the table, for three variables for both the inner and outerweb of the feather. Thus, the possiblerange of the sum of all wear scores(total wear score)was 6-18. Only the edgeof the terminal 0.5 cm of the feather tip was examined.

scoresand criteria Variable 1 2 3

Barb wear inner web No barb tips missingor A few barb tips missingor Missing barb tips in most (BI) and outer web broken, often white broken parts of the feather tip (BO) edgeat the very tip Barbule wear inner No barbules missing A few barbulesmissing Barbulesmissing several web (BUI) and outer places web (BUO) Hook wear inner web No hooks missing A few hooks missing Hooks missingseveral places, (HI) and outer web feather often looks trans- (HO) parent 962 S. A. SETHER, J. A. tiL.&S AND P. FISKE

50 1 Males

0 6 7 8 9 10 11 12 13 14 15 16 17 18 Total Wear Score

FIGURE 2. Total wear scorefor Great Snipe males captured during the breeding seasonin Gavalia, Norway, 1987-1990and1992.

yses due to damage (n = 8) or presenceof feather classified92.0% correctly(no old femalesor young lice (n = 2). Feathers from birds of known age males were classifiedwrongly, Wilk’s Lambda = included 74 old males, 10 old females and 3 0.703, x2 = 29.84, df = 1, P < 0.001). Females young males. (Fig. 3) showed significantly less wear than did Statistical analyses were performed using males(ignoringage;males:K= 10.98,SD= 3.03, SuperANOVA 1.11 (Abacus Concepts 1989) and n = 305; females: K = 9.35, SD = 3.13, n = 105; SPSS4.0.1. (SPSS 1990) for the Macintosh com- one-way ANOVA, F,, 4,,8= 22.11, P < 0.001). puter. To reduce the probability of falsely re- Considering only known old birds, females still jecting null-hypotheses in comparing the success showed less wear than did males, although the of the various aging methods, we adjusted the difference was not significant (males: K = 8.64, significance level to take account of the number SD = 1.88, n = 74; females: 52= 7.5, SD = 1.35, of tests performed. This was done using the se- n = 10; one-way ANOVA, Fl,82= 3.38, P = 0.07, quential Bonferroni technique (Holm 1979, Rice ns). 1989). Discriminantanalysis using all wearscore vari- ables.Discriminant analysis models using all six RESULTS wear scorevariables (seeTable 1) classified98.7% AGE DETERMINATION BASED ON of males and 98.9% of both sexesto the correct FEATHER WEAR agegroup. Again no females or young males were Discriminantanalysis using total wear score. incorrectly classified (standardized canonical There was no overlap in the total wear score for discriminant function coefficients for males, di- old (X = 8.64, SD = 1.88, n = 74) compared to rect method: BI = 0.363, BO = 0.526, BUI = young males (X = 15.0, SD = 1.0, n = 3) with O.lOl,BUO=0.227,HI=-0.151,HO=0.399; younger males showing more wear (see Fig. 2, Wilk’s Lambda = 0.637, x2 = 32.5, df = 6, P < one-way ANOVA, F,,,, = 33.54, P < 0.001). A 0.001; standardized canonical discriminant discriminant analysis using total wear score as function coefficients for both sexestogether, di- the sole predictor variable, classified 90.9% of rect method: BI = 0.368, BO = 0.526, BUI = the males correct (no young birds were misclas- 0.071, BUO = 0.216, HI = -0.156, HO = 0.420; sified, n = 74 old, 3 young, Wilk’s Lambda = Wilk’s Lambda = 0.644, x2 = 36.06, df = 6, P 0.69 1, x2 = 27.54, df = 1, P < 0.001). By in- < 0.001). A stepwise procedure classified cor- cluding known old females (n = 10) the model rectly the samepercentages as above of both males AGING OF GREAT SNIPE BY FEATHER WEAR 963

30 Females

v) 25 z =8 20 IA 5 15 zi aE 10

z 5

0 I I I 1 I I 6 7 8 9 10 11 12T14 '15'16 '17 ' Total Wear Score

FIGURE 3. Total wear scorefor Great Snipe females capturedduring the breedingseason in G&v&lia,Norway, 1987-1990 and 1992. alone and males and females together, but did Subjectiveestimation of age.A subjective as- not include BUI and HI (standardized canonical signment of age (young, intermediate, old) by discriminant function coefficients for males, in simply looking at the featherscorrelated well with the same order as they entered the model ac- wear score(n = 410, r, = -0.85, P < 0.001) but cording to the stepwisecriteria: BO = 0.527, HO there was some overlap in wear score between = 0.323, BI = 0.354, BUO = 0.237; Wilk’s the agegroups (Fig. 4, only males shown). Ninety Lambda = 0.64, x2 = 32.57, df = 4, P < 0.001). of 410 feathers (22.0%) were judged intermedi-

35

UJ 30 b r, 25 it IA 20 6 $ 15

zf 10

5

0 6 7 8 9 10 11 12 13 14 15 16 17 18 Total Wear Score

FIGURE 4. Subjective assignmentof age in relation to total wear score in Great Snipe males captured during the breeding seasonin Gavalia, Norway, 1987-1990 and 1992.

AGING OF GREAT SNIPE BY FEATHER WEAR 965 scores separated significantly more males than any of the models using morphology, as did the model using only total wear score. The fraction of males correctly classified by the subjective guessingof age was lower than both the discrim- inant model using all wear scoresand the model using only total wear score.The subjective guess- ing classifiedmore males than the stepwisemod- el using morphology, but not more males than the other models using morphology (x2 tests; 15 comparisons, significanceadjusted by sequential Bonferroni technique). Further, there was a ten- Young Old Young Old dency that the model using all wear scoressep- Males Females arated more males than the model using only total wear score (98.7% vs. 90.0%, two-tailed FIGURE 6. Mean (&SD) number ofwhite tail feath- ers (NWTF, tail feathers with more than 50% white) Fisher exact test, P = 0.063, ns). during the breeding season for young and old males and females, 1987-1992. Birds grouped to age as in DISCUSSION Figure 5. The difference in NWTF between young (n Our results demonstrate that one year old (first = 66) and old (n = 223) maleswas significant(Kruskal- Wallis one-way ANOVA, correctedfor ties, x2 = 6.63, summer) Great Snipe showed more primary P = 0.01). The difference in NWTF between young (n feather wear than older birds during the breeding = 13) and old (n = 99) females was not significant season,and that the extent of wear can be used (Kruskal-Wallis one-way ANOVA, corrected for ties, to age individuals. By including all wear scores x2 = 0.93, P = 0.33, ns). in a discriminant model instead of the sum of wear scores(total wear score), the percentageof report, known to us, of a sex-related difference males correctly classified to age increased. This in featherwear is the finding by Francis and Wood might be becausethe difference in wear between (1989) that female primaries wear faster in some young and old birds differed between the wear speciesof wood-warblers (Parulinae) than male variables. Differential wear on the outer web primaries. variables seemed to be more important in dis- Discriminant analysis based on feather wear criminating agesthan wear on the inner web vari- was a better predictor of age than analysis using ables. This is probably a consequenceof the outer morphological variation. However, several mor- web being more exposed than the inner web. phological variables contributed significantly to Likewise, barb wear was more important than discriminate between young and old males. Age- hook wear, which was more important than bar- related difference in wing length is a common bule wear (based on the standardized canonical phenomenon in birds (see referencesin Alatalo discriminant function coefficients). Therefore, et al. 1984, Francis and Wood 1989, Nakamura total wear score might include unnecessary 1990). In Great Snipe, this might simply be be- “noise.” However, there was no overlap between cause of more primary feather wear in young the age groups in total wear score. birds. In addition, the length of new primary Females showed less wear than males when feathersmay increasewith age, as has been found ignoring age, but no female known to be young in other shorebirds (see e.g., Pienkowski and was available to us. Sex-related differences in Minton 1973). The amount of white on the tail feather wear in this speciesmight partly be due of Great Snipe males is previously known to be to males being more exposed to contact with age-related (Hoglund et al. 1990a), but also to vegetation during their lekking behavior. Among fluctuate between years (Hoglund et al. 1992). old males we found an increase in total wear Elsewhere,we will explore the effectsof age, year scoreduring the breeding season.Unfortunately, and cohort on morphological variation in this too few old females were available for compar- species. ison. However, the difference in wear between When we simply looked at feathers without the two sexeswill probably also be influenced by using a microscope, we were unable to age all the timing of molt the preceding fall, as Devort feathers correctly, and about 20% were judged and Paloc (1992) found that females complete intermediate. Although this visual impression primary molt later than males. The only previous correlated well with total wear score, there was 966 S. A. !ÐER, J. A. tiL& AND P. FISKE

TABLE 2. Summary of the juvenile molt pattern and differential primary feather wear of some sort is methods for aging Nearctic and Palearctic shorebirds an available aging method during the breeding during the breeding season(see Appendix 1 for data). season,and the only method to age all individ- Numbers refer to number of species. We have here counted Pluvialisdominica dominica and P. dominica uals in 56.6% of the species. For some species jiilva as two separatespecies. this involves comparing the outer primaries with the inner, as young birds will have replaced only the outer primaries. Such young birds show con- trasting degree of wear between the inner and outer primaries, whereas old birds show evenly new primaries. In such casesit is relatively easy All 2y individuals have older primaries 13 64 to age most individuals during the breeding sea- than adults or show contrast be- son. However, in most speciesno young birds or tween old and new (all individuals only some will molt the outer primaries in spring. can potentially be aged by primary wear). In this case one could either examine cut-off feather tips the way we have described or, if the Some, but not all 2y individuals, have 1 29 older primaries than adults or show difference in wear is more pronounced, test the contrast between old and new (some reliability of age determination in the field on a individuals can potentially be aged sample of birds with known age. In addition, one by primary wear). should always check whether there is any con- All 2y individuals have molted the ju- 2 4 trast in wear between the inner and the outer venile primaries (no individuals can primaries. We have never noticed such partial be aged by primary wear). postjuvenile primary molt in Great Snipe. In other species,it is probably impossible to age all individuals according to feather wear as some overlap. This method may be of a higher some young birds molt all primaries before the value in the field where it is possible to look at breeding season (26.5% of the species,Table 2 more feathers on the same . This eliminates and Appendix 1). In 5.3% of the species it is the need for cutting off feather tips. Our expe- probably impossible to age any individuals ac- rience is, however, that some birds must be left cording to primary feather wear as all young birds unaged also in the field as wear will be judged as molt all primaries before the breeding season. intermediate. For other species of shorebirds, Beware that variation in molt pattern among there may be more distinct differences in wear young birds is poorly known in most shorebirds, between young and old birds. Then there should and is generally in need of more study. Note that be no need for cutting off feather tips, but one in some speciesthere is geographical variation should always compare the effectivenessof the in the molt pattern of young birds. Note also that aging method for a sample of birds with known in some speciesmany 2y birds (as well as some age, and also consider the inclusion of a group older) do not migrate to the breeding grounds in of birds with “intermediate wear.” If one needs their first spring, but instead spend this summer to cut off feather tips, this should be done for the in the south (McNeil 1970, van Dijk et al. 1990). feathers most exposed to wear (one of the out- These 2y individuals might molt differently from ermost primaries). Our experience with Great thosewho migrate, but this is largely unexplored. Snipe is that only the terminal 0.5 cm of the We have not been able to indicate suchvariation feather need to be examined, and thus cut off. in Appendix 1, and we present information on This minimizes one possible harmful effect of the molt of 2y birds ignoring their migratory sta- the method: that the tips of feathers nearby the tus. Melville (198 1) examined migrating Cufidris one cut off tend to be damaged (pers. observ.), ferruginea in spring in Hong Kong, and found probably becausethey become more exposedto birds with fresh primaries (adults), all primaries wear and tear. worn, only inner primaries worn or with ongoing MOLT PATTERN AND THE SCOPE FOR primary molt. This suggests(contra Melville AGING OF SHOREBIRDS BY 198 1) that some 2y birds of this speciesmigrate PRIMARY WEAR to breeding areas, and also that both 2y birds For the majority of Nearctic and Palearctic that do not molt and those who molt their outer shorebirds(6&l%, seeTable 2 and Appendix l), primaries may migrate. Melville (198 1) also ex- AGING OF GREAT SNIPE BY FEATHER WEAR 967

amined some C. ruficollis with abraded pri- LITERATURE CITED maries. This suggeststhat 2y birds of this species ABACUSCONCEPTS. 1989. SuperANOVA: accessible also might migrate to the breeding areas, al- generallinear modeling. Abacus Concepts,Berke- though many do not (Paton and Wykes 1978). ley, CA. In several speciesof shorebirds,2y individuals ALATALO,R., L. GUSTAFSSON,AND A. LUNDBERG.1984. Why do youngbirds have shorterwings than older molt their primaries earlier in the fall than do birds? Ibis 126:410-415. older birds (e.g., Haematopus ostralegus, Boere BARTER,M. A. 1988. Biometrics and moult of Lesser 1976, Wilson and Morrison 1981; Pluvialis Golden Plovers Pluvialis dominica jiilva in Vic- squatarola, Boere 1976, Prater et al. 1977; Cal- toria. Stilt 13:15-19. BARTER,M. A. 1989. Bar-tailed Limosa lap- idris can&us, Boere and Smit 198 1a, Barter 1992; ponica in Australia. Part 2: Weight, moult and C. alpina, Gromadzka 1986; Limosa lapponica, breeding success.Stilt 14:49-53. Boere 1976; Numenius arquata, Cramp and Sim- BARTER,M.- 1992. Distribution, abundance, migra- mons 1983; Arenaria interpres, Boere 1976, tion and moult of the Red Knot canutus Branson et al. 1979). Thus, in some speciesit rogersi. StudyGroup Bull., Suppl.64:64- 70. might be possible to separateboth first summer, BARTER,L., ANDM. BARTER.1988. Biometrics,moult second summer and older individuals using pri- and migration of Large Sand Plover Charadrius mary wear (see Johnson and Johnson 1983 on leschenaultiispending the non-breeding seasonin Pluvialis dominica fulva). Australia. Stilt 12:33-40. We have not included information on adult BARTER,M., AND S. DAVIDSON. 1990. Ageing Pale- arctic in the hand in Australia. Stilt 16:43- primary molt in Appendix 1, but beware that the 51. timing of adult molt varies among species.In the BARTER,M. A., A. JESSOP,AND C.D.T. MINTON. 1988. Calidris (see Holmes 1966, 1971, 1972; Red Knot Calidris canutus rogersi in Australia. Bengtson 1975), some speciesmolt all primaries Part2: Biometricsand moult in Victoria and north- western Australia. Stilt 13:20-27. on the breeding grounds before migration in fall BECKER,P. H. 1981a. Kentish Plover, p. 122-128. (C. maritima, some populations of C. alpina), In C. J. Smith and W. J. Wolff [eds.], Birds of the others molt only some primaries (i.e., suspended Wadden Sea. A. A. Balkema, Rotterdam. or “arrested” molt, see Ginn and Melville 1983 BECKER,P. H. 1981 b. Ringed Plover, p. 113-l 2 1. In C. J. Smith and W. J. Wolff [eds.], Birds of the for terminology) before migration (C. mauri) and Wadden Sea. A. A. Balkema, Rotterdam. some migrate before molting primaries on the BENGTSON,S.-A. 1975. Timing of the moult of the wintering grounds (C. melanotus, C. bairdii, C. Purple Calidris maritima in Spitsber- pusilla). This will probably influence the degree gen. Ibis 117:100-102. of difference in primary wear between first-sum- BOERE,G. C. 1976. The significanceof the Dutch Wadden Sea in the annual life cycle of arctic, sub- mer and older individuals. Another potential arctic and boreal waders. Part 1. The function as problem is that the strategy and timing of adult a moulting area. Ardea 64:2 1O-29 1. primary molt may vary within a species(e.g., in BOERE,G. C., ANDC. J. SMIT. 1981a. Knot, p. 136- C. alpina, seereferences in Holmgren et al. 1993) 145. In C. J. Smit and W. J. Wolff [eds.], Birds of leading to variation in the degreeof primary wear the Wadden Sea. A. A. Balkema, Rotterdam. BOERE,G. C., AND C. J. SMIT. 198lb. Sanderling, p. among adult birds the following breeding season. 145-151. In C. J. Smit and W. J. Wolff [eds.], Although the completion of primary molt in adult Birds of the Wadden Sea. A. A. Balkema, Rotter- Great Snipe varies by several months (Devort dam. and Paloc 1992), we have here demonstrated that BRANSON,N.J.B.A., AND C.D.T. MINTON. 1976. Moult, measurementsand migrations of the Grey adults consistently showed lesswear than young Plover. Bird Study 231257-266. birds during the breeding season. BRANSON,N.J.B.A., E. D. PONTING, AND C.D.T. MINTON. 1979. Tumstone populations on the ACKNOWLEDGMENTS Wash. Bird Study 26~47-54. BROWN,S. C. 1974. Common Sandpiper biometrics. For providingexcellent assistance with the fieldwork, Wader Study Group Bull. 11:18-24. we thank L. tifaldli, I. Myklebust,M. Myklebust,S. BURGER,J., AND M. HOWE. 1975. Notes on winter Nyb0, T. H. Ringsbyand S. L. Svartaas.We would feeding behavior and molt in Wilson’s Phalarooe. like to pay specialthanks to the Brettenfamily, for- Auk 92~442-451. merly at KonasvoldBioloaical Station. for muchhelD BURTT,E. H., JR. 1986. An analysisofphysical, phys- and friendlin&s over many years. The outline of Ai- iological, and optical aspectsof avian coloration pendix 1 was inspired by Pettersson(1983). Our paper with emphasis on Wood-Warblers. Ornithol. was improved by comments on earlier drafts by J. Monogr. 38:1-126. Hijglund and two anonymous reviewers. CLAUSAGER,I. 1973. Age and sex determination of 968 S. A. S/ETHER, J. A. KALAS AND P. FISKE

the (Scolopax rusticola). Dan. Rev. ropas, Vol. 7. Akademische Verlagsgesellschaft, Game Biol. 8: 1-18. Wiesbaden. CLXT~ON-BRCXK,T. H. [ED.]. 1988. Reproductive GRATTO,C. L., ANDR.I.G. MO~USON. 1981. Partial success:studies of individual variation in con- postjuvenile wing moult of the Semipalmated trastingbreeding systems.Univ. of ChicagoPress, Sandpiper Calidris pusilla. Wader Study Group Chicago. Bull. 33:33-37. CONNORS,P.G. 1983. , distribution, and GREEN.G. H. 1973. Some noteson Bar-tailed evolution of Golden Plovers (Pluvialis dominica ringing, biometrics & moult. Wader Study Group and PluviaZis.fulva).Auk 100:607-620. Bull. 8:4-8. CRAMP,S., AND K.E.L. SIMMONS[EDS.]. 1983. The GREEN,G. H. 1980. Total head length. Wader Study birds of the western Palearctic. Vol. III. Oxford Group Bull. 29: 18. Univ. Press, Oxford, U.K. GROMAD~KA,J. 1986. Primary moult of adult Dun- CRONAU,J. P., R.G.M. GOEDE,AND E. NIEBOER.1986. lins Calidris alpina of different age during autumn A new characterfor age determination in the Bar- migration. Var Fagelvlrld, Suppl. 11:5l-56. tailed Godwit Limosa lapponica.Ringing and Migr. H~~GLIJND,J., M. ERIKSSON,ANDL. E. LINDELL. 1990a. 7:135-138. Femalesofthe lek breedingGreat Snipe, Gallinago DARE,P. J., ANDA. J. MERCER. 1974. The timing of media, nrefer maleswith white tails. Anim. Behav. wing-mot& in the oystercatcherHaematopus os- 40:23-32. tralegusin Wales. Ibis 116:211-214. HQGLUND,J., J. A. KALAs, AND L. LBFALDLI. 1990b. DAVIES, S. 1982. Ageing criteria of Sanderlings in Sexual dimornhism in the lekkina Great Snine. Australia. Stilt 3:11-13. Omis Stand. 2 1:l-6. DEVORT,M. 1989. Towards a method to age and sex HQGLUND,J., J. A. K.&L.&S,AND P. FISKE. 1992. The Common Snipe (Gallinago gallinago) by external costsof secondarysexual characters in the lekking criterions. IWRB Woodcock & Snipe Research Great Snipe (Gallinago media). Behav. Ecol. 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Wolff [eds.], Birds of the spending the non-breeding seasonin north west Wadden Sea. A. A. Balkema, Rotterdam. Australia. Stilt 15:29-33. JACKSON,A. C. 19 19. The moult and sequence of FRY, G. 1990. Biometrics, moult and migration of plumagesof the British waders. Part 5. Brit. Birds Terek Sandpipers terek spendingthe non- 12:172-179. breeding seasonin north west Australia. Stilt 17: JEHL, J. R., JR. 1979. The autumnal migration of 24-28. Baird’s Sandpiper. Stud. Avian Biol. 2:55-68. G~NN,H. B., AND D. S. MELVILLE. 1983. Moult in birds. British Trust for Ornithology, Tring, Hert- JEHL,J. R., JR. 1987. Moult and moult migration in fordshire, England. a transequatoriallymigrating shorebird: Wilson’s GLUTZVON BLOTZHEIM, U. N. 1972. Zur mauservon . Omis Stand. 18:173-178. Charadrius hiaticula, dubiusund alexandrinus.J. JOHNSON,0. W. 1977. Plumage and molt in shore- Omithol. 113:323-333. birds summering at Enewak atoll. Auk 94:222- GLUTZVON BLOTZHEIM,U. N., K. M. BAUER,AND E. 230. BEZZEL. 1975. Handbuch der Vogel Mitteleu- JOHNSON,0. W. 1985. Timing of primary molt in ropas, Vol. 6. Akademische Verlagsgesellschaft, first-year Golden-Plovers and some evolutionary Wiesbaden. implications. Wilson Bull. 97:237-239. GLUTZVON BLOT~HEIM,U. N., K. M. BAUER,AND E. JOHNSON,0. W., ANDP. J. JOHNSON.1983. Plumage- BEZZEL. 1977. Handbuch der Vogel Mitteleu- molt-age relationships in “over-summering” and AGING OF GREAT SNIPE BY FEATHER WEAR 969

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APPENDIX 1. Molt of juvenile primary feathers,and age determination of Palearcticand Nearctic shorebirds during the breeding season.Information in footnotes refers to young birds unless otherwise stated, and molt refersto primary molt. Bewaregeographical variation and that youngbirds not migrating to the breedinggrounds might molt differently from migratingbirds, and that in some speciesa minority might molt all or some primaries without it being discovered. We have excluded some speciesonly marginally breeding in the Palearctic (Hae- matopusmoquini, Burhinus capensis,Esacus recurvirostris, Glareola lactea).

Other Shorebird species Molt* characteW SOUKFY

Rostratula benghalensis A? _ Haematopus ostralegus N + i416, 26,31,50 H. palliatus N ? 54 H. bachmani N 54,70 Ibidorhynchastruthersii N &?) 54 Himantopus himantopus N + 14, 27, 54 H. mexicanus N 54 Recurvirostraavosetta N i+, 14,54 R. americana N 54 Dromas ardeola ;+?, 14,54 Burhinus oedicnemus : (A) 14,54 N&i B. senegalensis L+, 14,54 Pluvianusaegyptius N*d _ 54 Cursorhiscursor A, 0, I? 14,54 Glareola pratincola A (+) 14,54 G. maldivarum A ? 54,75 G. nordmanni A 14,54 Charadriusdubius N, (A?) ;+) 14, 25, 54 C. hiaticula N, I, A* + 7,24, 25, 30 C. semipalmatus N ? 14,54 C. placidus N - 54 C. wilsonia N + 54 C. vociferus N _ 14,54 C. melodus N 54 C. pecuarius N, (A?) 14, 54, 62 C. alexandrinus N :; 6, 14,25 C. mongolus N, I, A* _ 14, 54,14 C. leschenaultii N, 0, (I), (A?)* - 1, 14, 54 AGING OF GREAT SNIPE BY FEATHER WEAR 971

APPENDIX 1. Continued.

other Shorebirdspecies Molt* character+ source‘

C. asiaticus N 14,54 C. veredus N G) 54 C. montanus N + 54 Eudromias morinellus N? + 14,54 Pluvialis dominica dominica A 35 P. dominicafilva N ?+I 2, 13, 36 P. apricaria N + 14,54 P. squatarola N 9, 14 Hoplopterusspinosus N 14,54 Vanelluscinereus N fL; 54 V. indicus N _ 14,54 V. vanellus N i-? 14,26, 54 Chettusiagregaria N 14,54 C. leucura N 2) 14,54 Aphriza virgata _ 54 CCaliiisrtuirostris :, A, (O), (I) 4, 14, 54, 72 2 pt?L,K&,‘ (A)* G) 5, 14, 54,68 C. alba (+I 14, 17,40, 67 C. pusilla N: 0: (A) _ 14, 28, 59 C. mauri 14,54 C. rujicollis : (0) 14, 20, 37,43, 54, 71 C. minuta 0: A, (N)* r:; 14,45,48, 54,63, 64 C. temminckii 0 (+I 14,54 C. subminuta _ 14,54 C. minutilla : 0 (A)* 14,42, 54, 58, 59 C. jiicicollis N: (d), (A) 14,54 C. bairdii N, (Oh (A) r:; 14, 32, 54 C. melanotus N, (A?) _ 14, 54 C. acuminata N, A, 0 4, 14, 54 C. ferruginea 0, (A), (N)* i-+) 4, 14, 19,37,44,45, 49, 54,64, 68 C. maritima N 14,54 C. ptilocnemis N ;+, 54 C. alpina N + 14,54 Eurynorhynchuspygmeus N 54 Limicola falcinellus (+,‘ 14, 22, 54 Micropalama himantopus go 14, 54, 59 Tryngitessubrujicollis A: (NT) b;l 14,54 Philomachuspugnax N, 0~ 14, 39,45,47, 54, 56, 64 Lymnoctyptesminimus N? - 14,54 Gallinago gallinago N ?* 14, 38, 54,66 G. media N _ 14, 18, 54, 61 G. stenura N _ 14,54 G. megala _ 54 G. hardwickii z _ 21,54 G. solitaria N? 54 G. nemoricola F+) 54 Limnodromus griseus : (0) - 14,54 L. scolopaceus N ’ _ 14,54 L. semipalmatus N - 54 Scolopaxrusticola N _ 12, 14, 54 Philohela minor N 41, 54, 57 Limosa limosa N G) 14,54 L. haemastica N 54 L. lapponica N, A* & 3,4, 14, 15,29, 54 L. fedoa - 54 Numenius minutus : (O), (A?) _ 14,54 N. borealis N ’ _ 54 972 S. A. !ÐER, J. A. tiL& AND P. FISKE

APPENDIX 1. Continued.

Other Shorebirdspecies Molt’ character+ sourc.?

N. phaeopus N, (A)* ’ - 14, 34, 54 N. tahitiensis 2 (A)i ? 34,54 N. tenuirostris _ 14,54 N. arquata N - 14, 52, 54 N. americanus 54 N. madagascariensis : (I) ;+) 4, 54,13 Bartramia longicauda N ’ _ 14,54 Tringa erythropus 14,54 T. totanus S (+,‘ 8, 14, 54 T. stagnatilis N, 0* _ 14,45, 54,64 T. nebularia N, 0* _ 8, 14, 45, 54, 64, 65 T. guttife N _ 54 T. melanoleuca N _ 14, 54, 59 T. jlavipes 0, (N) _ 14, 54, 59 T. solitaria 0, (A?) _ 14, 54, 59 T. ochropus N, (0) 14,54 T. glareola N, 0* F+, 14,45, 54,64 Xenus cinereus * 14,23, 54,69 hypoleucos z;:* (+?) 8, 10, 14,45,46, 51, 54,64 A. macularia A, (0) (+?) 14,54 Heteroscelusbrevipes _ 4, 53, 54 H. incanus “0: E (I) _ 34, 53, 54 Catoptrophorussemipalmatus 54 Arenaria interpres : (I)* ;+, 4, 14, 24, 34, 54 A. melanocephala N ’ - 54 Phalaropustricolor N, (A?) - 11, 14, 33, 54 P. lobatus N, A?* - 14, 54, 55,60 P. fulicarius N, (O?) ’ _ 14,54 * N = No juvenile primarymolt before the first breedingseason, 0 = Juvenile bids molt outer primariesbefore the first breedingseason, I = Juvenile birds molt inner primariesbefore the first breedingseason, A = Juvenile birds molt all primariesbefore the first breedingseason, ( ) = Only a minorit of birds molt in this way, ? = Uncertainty,l = Geographicalvariation. t.+ = & cable by other charactersduring the breedingseason, (+) = Only some birds ageableby other characters,- = Not ageableby other characters. DSources: 1) Barter 1988a,2) Barter 1988b, 3) Barter 1989,4) Barterand Davidson 1990,5) Bwteret al. 1988,6) Becker1981a, 7) Becker1981b, 8) Boere 1976.9) Bransonand Minton 1976, 10) Brown 1974, 11) Burgerand Howe 1975, 12) Clausager1973, 13) Connors1983, 14) Cramp and Simmons 1983, 15) Cmnau et al. 1986, 16) Dare and Mercer 1974, 17) Davies 1982, 18) Devort and Paloc 1992, 19) Elliot et al. 1976, 20) Evans 1975, 21) Frith et al. 1977, 22) Fry 1989, 23) Fry 1990, 24) Ginn and Melville 1983, 25) Glutz van Blotzheim 1972, 26) Glutz van Blotzheim et al. 1975,27) Glutz van Blot&&n et al. 1977,28) Gratto and Morrison 1981,29) Greene 197!, 30) HoIz 1987, 31) Hulscher 1981,32) J&l 1979, 33) J&l 1987, 34) Johnson1977, 35) Johnson1985, 36) Johnsonand Johnson1983, 37) Melvdle 1981,38) Milnster 1975,39) Mibuter 1991,40) Myers et al. 1985, 41) Owen and Krohn 1973, 42) Page 1974, 43) Paton and Wykes 1978,44) Paton et al. 1982, 45) Pearson1974, 46) Pearson 1977,47) Pearson1981,48) Pearson1984,49) F’iister 1972, 50) Plenkowskiand Knight 1975,51) Pienkowskiet al. 1976,52) Poslawski1969, 53) Prater and Marchant 1975, 54) Prateret al. 1977, 55) Schameland Tracy 1988, 56) Schmitt and Whitehouse1976, 57) Sheldonet al. 1958, 58) Spaans1976,59) Spaam 1979,60) Strewnann and Stresemann1966,61) this study,62) Tree 1973,63) Tree 1974a,64) Tree 1974b,65) Tree 1979, 66) Tuck 1972,67) Underhill and Whit&w 1977 cited by Boereand Smit 1981b, 68) Waltner 1976,69) Waltner and Sinclair 1981 cited by Urban et al. 1986, 70) Webster1942,71) WoebIer 1983, 72) Barter 1987, 73) Barter 1990,74) Barter 1991,75) Johnsonet al. 1991. dVariable timing of breedingseason and molt. eComplex and variable molt in winter in both youngand adult, possiblymore wearin youngnevertheless. ‘Birds wintering in the southernhemisphere often molt all or outer primariesduring the winter, thosewintering in the north do not. 8Mtister (199 1) foundthat both malesand femalesreplace outer primaries, c~nfm suggestions(Cramp and Simmons1983) that only somefemales molt outerprimaries. hYoung molt all primariesin spring,probably less wear than adults during the breedingseason. I Most of thosewho replaceall primarieswill be in moult until June. JSome molt also one or nmre inner primaries. ’ S&me1 and Tracy (1988) found primary wear not to be useful.This might be in accordancewith Strexmann and Stresemann(1966) who reportedprimary molt in spring,as opposedto the findingsof Pmteret al. (I 977). Both strategiesmay occur;perhaps only birds migratingto breeding areasmolt (Cram and Simmons 1983). ’ ’ Perhapssome s em&s molt outer primaries(F ’rateret al. 1977).

REFERENCES ADDED IN PROOF

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