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Notes on the breeding biology of Raso Lark Alauda razae PeterCastell Lecologiedel'AlouettedeRasoAlaudarazae especeendemiqueauxliesdu Cap-Vertetglobalement , menacee,estpeuconnue.Lauteurpresentedesdonnees,recolteesal’occasiondevisitesaRasopendant lesmoisdemarsetoctobre 1998, surlesexigencesdel’espececoncemantl’habitat, certainsaspectsde soneco-ethologie, parmilesquelslaparadeetl’accouplement, laconstructiondunid,latailledeponte, la duree de la couvaison et les soins parentaux. Le jeune est decrit pour la premiere fois. Introduction Population RasoLarkAlaudarazaeisrestrictedto,andnamedafter, Thepopulationhasbeenestimatedat40pairs(1968),20 theremoteanduninhabitedislandofRasointheCape pairs(1977and1981),atleast200birds(1986)andc250 VerdeIslands.Theislandcoversc7km2and.giventhe birds(1988,1990,1992).Itisunknownwhetherthelowest smallamountofavailablehabitat,thespeciesiscurrently numberwastheresultofprolongeddroughtoranincom- consideredEndangered1,althoughRatcliffeetaP,follow- pletecount4.However,inFebruary1998,justpriortomy ingaFebruary1998survey(seebelow),recommendthat firstvisit,RatcliffeetaPfoundjust92birdsinadetailed thiscategorisationberevisedtoCriticallyEndangered. census.InMarch,wesawonlyc40-50birds,butdidnot Thisspeciesresemblesaslightlysmallerbutmorestoutly- attemptapopulationcensus,mostinpairsbutalsoin builtSkylarkAlaudaarvensisandispalerandgreyerin partiesof5-6birds.Mostbirdswereconcentratedaround colorationwithacrestthatisrarelyapparentexceptwhen alargesandyareawithsparsebrownvegetation,nearthe BWP raised.Thebillislongerandstouter.Itisincludedin sea,butotherswerefoundinvariousareasoftheplain.In buttheaccountisshortandratherincomplete. October,pairswerewelldistributedthroughouttheplain. TogetherwiththreecolleaguesIsleptoutontheisland Iestimatethattherewere 100pairs, includingseveral during23-26March1998,andImadesubsequentday solitarymales,probablywithnearbyfemalesonnests. visitson23Octoberand29October1998.Theweather washotandoccasionallywindyinMarchandhotandvery Adult plumage windyinOctober.InMarchwefoundnofirmevidenceof BWP2statesthatthesexesaresimilarinplumage.Thereis, breeding,despiteconsiderablewatching.InOctober,I however,amarkedsexualdimorphism;malespossessa observeddisplay,mating,nest-building,andfoundseveral distinctlylongerandbulkierbill.Thebirdsarealways nestsandphotographedeggsandyoung.Thefollowing extremelyconfiding,makingsexingveryeasy.Somebirds, notessummarisetheseobservations. bothmalesandfemales,aredarkerincoloration.InMarch, thebirdsranaroundusaswelayinoursleepingbagsand, Habitat incommonwithIagoSparrowPasseriagoensis,woulddrink Approximatelyhalfoftheislandconsistsofsteep-sloping waterputoutfortheminourbottletops. andhighrockyground,unoccupiedbylarks.Theremain- derisalevelorgentlyundulatingplain,principallybare Breeding season groundstrewnwithrockswithscatteredpatchesofmeagre MostrainfallintheCapeVerdesisinAugust-November grassyvegetationonsandysoil,usuallyinshallowvalleysor andthetimingandquantityoflocalrainfalldeterminethe slightdepressions.RasoLarksoccupytheentireplainbut breedingseasonforlandbirds,includingRasoLark.The areespeciallyassociatedwiththevegetatedareas,inwhich birdsapparentlyhavetwobreedingseasons,amainone theyfeedandbreed.ThevegetationwasbrowninMarch fromSeptember-November,andalesssignificantonein andgreenandfreshinOctober.Allnestsfoundwerein February-April.Droughtsmaypersistforseveralseasons thesevegetatedareasandallwerebuiltatthebaseof,and andbreedingmaybesporadic4.Wefoundnofirmevidence partlyscreenedbyA6w/z7onpannosum.Thisplantistallerthan ofbreedinginMarch(butseesectiononsong)orrecently thesurroundingvegetationandhasbrightgreenleaves, occupiednests,despiteanextensivesearch.On23Octo- somewithyellowflowers.InbothMarchandOctober, ber,Isawnoflyingyoungbutfoundthreeyoungaged birdsdugsmallholesinthesoftsandysoilintheseareas, 12-13daysbytheirnest.Takingintoaccountanestimated presumablytoexposefooditems. incubationperiodof13days,anegg-layingperiodofthree Breeding biologyofRasoLark: Castell BullABC Vol6No2-103 Figure 1. Habitat ofRaso LarkAlaudarazae(green Figure 2. AdultmaleRasoLarkAlaudarazae<N. Williams) vegetatedarea) (P. Castell) Figure 3. NestofRaso LarkAlauda razaecontainingthree Figure 4. YoungRaso Lark Alaudarazaeaged 12-13days eggs (P. Castell) (P. Castell) daysandanest-buildingperiodoffivedays,nest-building prominentrocksandalsoinhoveringrisingflight(com- commencedonc20September.OnbothvisitsinOctober monlyuptoclOmaboveground),usuallyincloseproximity birdswerenest-building,twonestscontainedeggsand (andoftenimmediatelyabove)afemale.Maleswillpeifomi severalnestswereempty;therewerebrokenpiecesof asongflightandthenlandalongsidethefemale.On23 eggshellinsomenests,implyingpredation.Ifound11 OctoberIobservedapairontheground.Asecondmale recentnests,andmanyfreshscrapesinOctoberand, approachedthefemalebutwaschasedawayforatleast150 judgingbytheamountofsong,wasthepeakbreeding mbytheothermale.Thepairthenflewc100mandlanded periodinthisparticularyear. onthegroundinanareaofgravelandsmallrocks.With wingspartiallyopened,thefemalequivereditsentirebody Song, display and mating forc30 secbefore the male ranforward andthe pair InMarchweheardnosongonthefirsttwodaysofourvisit. copulatedforc5sec.Followingthis,thefemaleshookher m Therewaslightraininthenightof24Marchandafewbirds wingsandbothbirdsflewc30 toagreenvegetatedarea. sangbrieflythefollowingday.Rathersurprisingly,consid- Fromadistanceofc25mIwatchedthefemalegraba eringthetimeofyear,therewasheavyrainduringthenight beakfulofdrygrassstemsandthepairflewtoahalf-built of25Marchand,thefollowingmorning,severalmalessang nest.Approximatelyhalfofthegrasswaslostduringthe brieflyfromrocksandfromtheground.Wedidnotsee flight.Thepairhadcopulatedc30mfromthenest. songflighting. InOctober,malesweresingingthroughouttheplain, Nest-building especiallynearvegetatedareas.Thesongrecallsthatof BWP2providesnoinformationontheroleofthesexesin Skylarkandisdeliverednotonlyfromthegroundbutfrom nest-building.Inadditiontotheobservationdescribed 104-BullABC Vol6No2 Breeding biologyofRasoLark: Castell above,Iwatchedanotherfemalenest-building.Themale nentwhitelinebetweenthebillandtheeye.BWPprovides wasincloseattendance,whilethefemalecollectedmateri- nodetailsofthebarepartsoftheyoung,buttheseare als,butdidnotassist. illustratedinFig.4.Thisbirdhadnotraceofdownandwas yetunabletofly.Thegapeflangeswerewhiteandthe Nest mouthorange-yellowwithfiveblackmarkingsinsidethe Nestsofdesert-dwellinglarksareusuallyascrapeinthe mouth,threeonthetongue(twoatthebaseandoneatthe ground, constructedbythebirds, alongsideorpartly tip)andoneattheinsidetipofeachmandible;thetongue screenedbyarockorsmallbush,witharampartofstones spurswerewhiteandprominent.Thisfive-spotpatternis orpiecesofdriedearthattheopenside.Incontrast,Raso usualamongyoungofWesternPalearcticlarks2 butthe , LarknestscloselyresemblethoseofSkylark,havingno markingsonthisRasoLarkwerelonger,thinnerandless rampart.AroundscrapeclOcmwideandc5cmdeepinthe distinctthanthoseinotheryounglarkswhenrecently centreismadeinsoftsandyground.Thescrapeislined hatched.Itisunknownwhetherthemarkingsarerounder, withathickpadofdrygrassstems.Somenestscontained darker,andmorecloselyresemblethoseofotheryoung afewfeathers(possiblywind-blown?)inthelining.Allwere larkswhenthebirdsarerecentlyhatched,butthisseems atthebaseof,andusuallypartiallyscreenedby,Abutilon possible. plants,commonlycl5cmtall. Tending of the young Breeding territory Again,BWPoffersnoinformationontheroleofthesexes Asdemonstratedabove,maleRasoLarksappeartodefend in this respect. I wasfirstattracted totheyoungbird territoriesneartheirnestsandfemales. Ididnotmeasure describedabovebyanadultmaleRasoLark.AsIap- m thedistancesbetweennestsbutseveralwerewithincl50 proachedavegetatedarea,themaleappearedafewmetres ofeachother.Thescatteredvegetation,requiredforboth awayfrommeandranbackwardsandforwardsinan feedingandbreeding,isclearlythemostcrucialfactorin agitatedmannerwithanerectcrest.AsIwatched,afemale thedelimitationofterritory. andthreeyoungflutteredoutofthevegetationelmfrom anobviouslyrecentlyoccupiednest.Bothadultsfedthe Eggs and clutch size youngonunidentifieditemsincluding,ononeoccasion,a Fig.3illustratesanestcontainingthreewarmeggson29 long-wingedinsect.Amongthevariouslarkspeciesbreed- October.Theeggsaretypicalofalarkandcloselyresemble ingintheWesternPalearctic,feedingandtendingofthe thoseofWoodlarkLullulaarborea.Theyaresubelliptical, youngistypicallyundertakenbybothsexes,whereknown. smoothandglossy,withagreyishwhitebackgroundand RasoLarkappearstobehavesimilarly. darkbrownmarkings,heavilyconcentratedatthelarger end.On29October,anothernestcontainedonewarmegg, Predation thatwasclearlybeingincubated.Themarkingsonthisegg Asstatedpreviously,fournestscontainedfragmentsof werechocolate-brownanddenselyconcentratedatthe unhatchedeggshells.AdultRasoLarks,incommonwith larger end. Four other nests contained fragments of otherlarks,wouldalmostcertainlyremovehatchedegg- unhatchedeggshells.Thebroodofthreeyoung,foundon shellsfromtheirnests InOctober,apairofBrown-necked . 23October,suggeststhatmostclutchescontain1-3eggs. RavenCorvusruficollis apotentialpredator,wasshowing , considerableinterestinthevegetatedareas. Incubation and the role of the sexes BWP2statesthattheincubationperiodis13days,under- Conclusions takenbybothsexes(basedoninformationfromthe1890s), Thispaperprovidesnewinformationonthebreeding butthatconfirmationisrequired.Thisperiodisconsistent biologyofthelittle-studiedRasoLark. Someaspects,such withtheincubationperiodofotherlarks.InOctober,only asroleofthesexesinnest-building,incubationandtending thefemalewasfoundclosetothenestcontainingtheone oftheyoung,requirelongertermstudy. warmegg.Onthreevisitstothenestcontainingthreeeggs, bothbirdswereseennearthenestwhenapproached;Iwas Acknowledgements unabletodeterminewhichmemberofthepairhadbeen ThanksareduetoDrColinHarrison,whomadevaluable incubating,butthefemalewasalwaysmuchclosertothe comments on an earlierdraft ofthis paper, and Roy nestthanthemale. Vickery,CuratorofFloweringPlantsattheNaturalHis- toryMuseuminLondon,foridentifyingtheplantspecies Young mostassociatedwithRasoLarknests.1' SeeFig.4oftheRasoLarkaged12-13dayson23October. Ithasawell-developedchestnut-browntailandapromi- Breeding biologyofRasoLark: Castell BullABC Vol6No2-105 References 1. Collar,N.J.,Crosby,M.J. andStattersfield,A.J. 1994. Birdstowatch2: theworldlistofthreatenedbirds. Cambridge, UK: BirdLife International. 2. Cramp, S. (ed) 1988. The Birds of the Western Palearctic. Vol 5. Oxford: Oxford UniversityPress. 3. Harrison, C. and Castell, P. 1998. BirdNests, Eggs "THE MAGICAL MISTY andNestlingsofBritainandEurope. New edition. INSI VUMSA MOUNTAINS London, UK: HarperCollins. ZIMSASWE 4. Hazevoet, C.J. 1995. The Birds ofthe Cape Verde Islands:anannotatedcheck-list.BOUCheck-listNo Seldomseen is- well Icnown 13- Tring: British Ornithologists’ Union. internationallyforits special 5. Ratcliffe,N.,Monteiro,L.R.andHazevoet,C.J. 1999. Status of Raso Lark Alauda razae with notes on jSwynnerton'sRobin-Stripe-cheekedSulbul threatsandforagingbehaviour.BirdConseru.Inter- -Robert'sPrinia-StarredRobin national9: 43-46. -OrangeThrush Crimsonwing Fairlawn, 679ChesterRoad, GreatSutton, South Wirral -SuffspottedFlufftail-WhitetailedFlycatcher L662LN, UK. jtjojnajmjejafjewj!j FORFURTHERINFORMATIONAND BOOKINGSWRITETO: 27T> HOLIDAYCOTTAGES BOX441 MUTARE ZIMBABWE P.O. • • TELEPHONE: (20320)215115 FAX/AN5WER: (20320)02337 African Birding Planning a holiday ?..sneaking out ofa conference ?.. have some hours to spare?? Join 3 of the region’s top professional ornithologists based in Cape Town for a variety of specialist tourstoexperienceSouthAfrica’s Cape *and Karoo endemics. Fax: +27-21-783 3903 Cell: 083-296-0147 E-mail: [email protected] Http//home mweb co za/kb/kbarnes : . . . 106-BullABC Vol6No2 Breeding biologyofRasoLark: Castell