Partial primary moult in first-spring/summer Common Sandpipers Actitis hypoleucos M. NICOLL 1 & P. KEMP 2 •c/o DundeeMuseum, Dundee, Tayside, UK 243 LochinverCrescent, Dundee, Tayside, UK Citation: Nicoll, M. & Kemp, P. 1983. Partial primary moult in first-spring/summer Common Sandpipers Actitis hypoleucos. Wader Study Group Bull. 37: 37-38. This note is intended to draw the attention of wader catch- and the old inner feathersare often retained (Pearson 1974). ers to the needfor carefulexamination of the primariesof Similarly, in Zimbabwe, first-year Common Sandpipers CommonSandpipers Actiris hypoleucos,and other waders, replacethe outerfive to sevenprimaries between December for partial primarywing moult. This is thoughtto be a diag- andApril (Tree 1974). It thusseems normal for first-spring/ nosticfeature of wadersin their first spring and summer summerCommon Sandpipers wintering in eastand southern (Tree 1974). Africa to show a contrast between new outer and old inner While membersof the Tay Ringing Group were mist- primaries.There is no informationfor birdswintering further nettingin Angus,Scotland, during early May 1980,a Com- north.However, there may be differencesin moult strategy mon Sandpiperdied accidentally.This bird was examined betweenwintering areas,since 3 of 23 juvenile Common and measured, noted as an adult, and then stored frozen un- Sandpiperscaught during autumn in Morocco had well- til it was skinned,'sexed', andthe gut contentsremoved for advancedprimary moult (Pienkowski et al. 1976). These analysis.Only duringskinning did we noticethat the outer birdswere moultingnormally, and so may have completed primarieswere fresh and unworn in comparisonto the faded a full primary moult during their first winter (M.W. Pien- and abradedinner primaries.The moult on both wingswas kowski, pers.comm.). uniform,with the five outerprimaries having been replaced, Do first-summerCommon Sandpipers regularly return to i.e. a moultscore of 0555(Figure 1). In addition,the tenth the breedinggrounds? Holland et al. (1982) recordedfour secondaryand first tertial had been replaced. The contrast birds,ringed as chicks,which bred successfullyduring their betweenthe old andnew feathersin the primarieswas easy first summer.Delayed recruitmentin this populationwas to see,but wasless obvious in the secondariesand especially consideredunlikely. The bird from Angus(Figure 1) was a the tertials, as occursalso with SemipalmatedSandpipers male, and its testis size suggestedthat it was capable of Calidrispusilla that have partial moult (Gratto & Morrison breeding.During the 1982 breedingseason, 3 (19%) of 16 1981). CommonSandpipers that we caughtin Glen Lethnot,Angus, Prater et al. (1977) state that in first-winter Common showedpartial primary moult, their moult patternsbeing Sandpipersin the tropicsand southernhemisphere "a small 0456, 0505 , and 0654 . So some Common Sandpipers do return percentagemoult outer primaries only". However, after to breedin their first summer,and at leastsome have partial examiningthe originalsources, we feel thatPrater et al. have primary moult. greatlyunder-estimated the occurrenceof partialmoult in We can find no other reports of Common Sandpipers first-yearbirds. In Kenya, first-winterbirds renew most of showingpartial primary moult on the breedinggrounds, or their flight feathersbetween January and March. The moult on springor autumnpassage. However, it seemsprobable usuallyproceeds outwards from the fourthor fifth primary, thatit is a featurethat is beingmissed by ringers.For exam- ple, Brown(1973) mentionedno examplesof partialprimary moultamongst 200 adultCommon Sandpipers mainly from )fi•• Britainthat had been examined for moult. Also the bird we examinedwould have been released asan adult, if it hadnot died.We feel that with more vigilance, ringers will find par- .,•_ tialprimary moult to be common in first-year Common •-'••.} "•-'-•' ,•-•••' •x Sandpipersonthe breeding grounds, Indeed, partial primary '•1/ '•..,.-•'.'"• ß \•x '.•'.. x-.. ," :."•7' .,3'2,.•; '.• -•:• •__•-__-= moultmay be widespread ß amongst first-year waders, sinceß / / ..d ].,' "';'•:i"' -'•X• •'. '"' '"•. ' --.• :•'•-••Y.•. -----•:.:,• it hasbeen found also in CurlewSandpipers Calidris ..( ..i .-.•• .•-•_•.:-.', ........', '•'':•.• "•":"•=.: '-;' •--•,,•_•,•d•,,,-.-•--• -' ' - ,,. fierru g tnea, RnffsPhdomachus Pgu nax, MarshSand- , 4 t l--,J•,.:;:• !"" •,: -&:'"' :..',";:.: :•:---r,, '......t.,.'-••....,.ß -• '•,¬•,r,•'j•4!,•;•jlit•2, ' pipers • rtnga stagnatttts,•JreensnanKs • rtnga ! ,'•J" ' : •:.'.'--'.-',:'-::-:':J:' •".:{•c'dC ".-'.::'.':/.'. '"'."" •..-:::v.',.:,;.:._.,: • •Z,'•'""" '*-'•-,'-.,.-'-.--...'...."-.."-'.•...;, %,.' •.•&'•'•,//i%•4' ,:T,.•u,•e,,&•.'•;-}•'•'•'7; nebularta. andWood Sandpipers . Trtnga. glare- [ I •: }'•fi'•. • ' '•'•'[r/[•'',•{•{l•C'' olawintering inZimbabwe (Tree 1974). In _ ] /,,'. ',_-(Sf,q"- ... •------•--___•t • Hardangervidda,Norway, in June1982, mere- • . •..c••-m..z.. -- Innerprimaries &secondaries Outer•v•pnmar,ee . bers ofthe Jo,nt . Tay/Gramp,an . Exped,t,on.. [ ,.,/•/ worn& faded fresh nest-trappeda female Ruff showingpartial pri- )' •f' marymoult (0753), and a DotterelCharadrius /, 17I morinelluswith a primarymoult pattern of /• 721 "y Figure1.The partial wing primaryofa Common moult (0sfis).Sandpiper ' showing this0 5 latter0 onbirdboth appearedwings. Allthethesame old age.feathers on Bulletin 69 Special Issue July 1993 82 Morphometrics:moult 83 Acknowledgements of the SemipalmatedSandpiper Calidris pusilla. Wader StudyGroup Bull. 33: 33-37. We are grateful to the various landowners,particularly Holland, P.K., RobsonJ.E. & Yalden, D.W. 1982. The breedingbiology of the CommonSandpiper Actitis hypoleucos in thePeak District. Bird Mr H.N. Keswick,Hunthill Estate,who allow us to ring birds Study 29: 99-110. on their land, and alsoto the ScottishOrnithologists' Club, Pearson,D. 1974. The timing of wing moult in somePalearctic waders who helpedto financethe work of the Tay and Grampian winteringin East Africa. Wader StudyGroup Bull. 12: 6-12. RingingGroups in Norway, and to Keith Brockiefor his Pienkowski,M.W., Knight, P.J., Stanyard,D.J. & Argyle, F.B. 1976. The illustration. primarymoult of waderson the Atlanticcoast of Morocco.Ibis 118: 347-365. Prater, A.J., Marchant, J.H. & Vuorinen, J. 1977. Guide to the identifica- References tion and ageingof Holarctic waders.BTO Guide No. 17. BTO, Tring. Tree, A.J. 1974. The useof primarymoult in ageingthe 6-15 monthage Brown,S.C. 1973. CommonSandpiper biometrics. Wader Study Group classof some Palearctic waders. Safring News 3(3): 21-24. Bull. 11: 18-23. Gratto, C.L. & Morrison, R.I.G. 1981. Partial post-juvenilewing moult Estimating the parameters for primary moult - a new statistical model L.G. UNDERHILL Avian DemographyUnit, Department of StatisticalSciences, University of Cape Town, Rondebosch 7701, South Africa Citation: Underhill, L.G. 1985. Estimating the parameters for primary moult- a new statistical model. Wader Study Group Bull. 44: 27-29. Introduction Summerset al. 1983). Most of the other methodsconsidered by Summerset al. (1983) are ad hocattempts that have been It haslong been recognized that the regression methods that devisedto overcomeheteroscedasticity. havebeen used to estimatethe parametersof primarymoult One approachwhich does apparently eliminate the prob- areunsatisfactory (see for examplePimm (1976)). Summers lem of heteroscedasticityis to reversethe roles of date and et al. (1983) comparedseven regression methods, most of moultscore, treating moult score as the independent variable which haverecently been used in the analysisof moult, for anddate as the dependent variable (Pimm 1976).This is logi- estimatingthe startingdate, completion date and duration of cally absurd,as thereis no sensein which date dependson moult. Their estimatesof startingdate variedfrom 29 June moult score.The bird-ringerchooses the dateson which to to 31 July (32 days),of completiondate from 2 to 24 Octo- catch birds, and observes the scatter of moult scores in the ber (22 days),and of durationfrom 72 to 109 (37) daysfor samplecaught on thesedates. (Unless birds are caughtat the RedshankTringa totanus.There is obviouslya needfor a standardand statisticallysound method. D E F Ordinary linear repression The simplesttechnique for estimatingthe parametersof moult (startingand completiondates and duration)is to fit a linear regressionof moult scoreon date,using all birds activelymoulting. The reasonfor the poor performanceof linear regressionin this caseis straightforward.One of the underlyingassumptions of leastsquares regression is thatthe variance(variability) of the dependentvariable (moult score) is the samefor all valuesof the independentvariable (date). This assumptionis grosslyviolated, sinceactive primary A B moult scoreslie between1 and(usually) 49, sothat near the DATE commencement and conclusion of moult there'is less vari- ability in moult scorethan duringthe middle of the moult Figure 1. In a plot of moult score against date, the points gener- period (Figure 1). The technicalterm for lack of constant ally lie withina parallelogramACFD. The "average bird"is depicted varianceis heteroscedasticity.The regressionline runs diago- by the line BE. The arrows demonstratethat the variabilityof moult nally acrossthe longaxis of the parallelogramthat encloses score is not constantfor all dates (see text). Ordinary linear regres- the scatterof points,effectively giving the startingand com- sion gives the dashed line, indicating the starting and completion pletiondate of the first and last birdsrespectively in the dates for the first and last birds, respectively, in the population, population,rather than the averagebird (Figure1), (seealso rather than the average bird. Bulletin69 Special Issue July 1993 .