Mate replacement and male brood adoption in Lapwings Vanellus vanellus TERJE LISLEVAND •*, GAUTE BiDGRiDNSTiDL •, INGVAR BYRKJEDAL2 & JO ESTEN HAFSMO • •Departmentof Zoology,AIl•gaten 41, N-5007 Bergen,Norway, e-maih terje.lislevand@zoo. uib. no; 2Museumof Zoology,Mus•plass 3, N-5007 Bergen,Norway Lislevand,T., Gronst½l,G.B., Byrkjedal,I. & Hafsmo,J.E. 2001. Mate replacementand male broodadop- tion in Lapwings Vanellusvanellus. Wader StudyGroup Bull. 95: 55-58. Mate replacementand male broodadoption has been reported in a rangeof bird species,but doesnot seem to havebeen reported before now in waders.We presentdetails of a casewhere a bigamousmale Lapwing Vanellusvanellus died at the onsetof egg laying, whereuponhis territorywith the two femaleswas divided betweenand taken over by two neighbouringmales. One of the replacementmales incubatedon the nest of his new mate, while the otherbehaved indifferently. Based on currentbrood adoptiontheory, it is sug- gestedthat the males'behaviour could arise from either(1) the chanceof gainingfuture fitness benefits, or (2) confidenceof paternityor (3) a combinationof both. INTRODUCTION 1998, from 20 March to 10 May, covering the period from territoryestablishment until late chick-rearing.We recorded The degreeof parentalcare by malesshould depend on their pair bondsby makingfield sketchesof the birdsthat showed certainty of paternity (Trivers 1972, Westneat & Sherman characteristicplumage markers (Byrkjedal et al. 1997) and 1993, Houston1995). Yet, observationsof replacingmales madeit possibleto separateall studiedindividuals. Territory adopting and caring for offspring apparently fathered by boundarieswere mappedby plotting the locationsof males anothermale existfrom at least 17 speciesof birds(Rohwer and their flight displayroutes. The main studyincluded 32 1986, Meek & Robertson1991). Parentalcare for the young territorial males with 46 nestingfemales in a total area of of othermales thus appears altruistic, and the adaptivevalue c. 20 ha. Figure 1 showsa map of the territoriesof the birds of this behaviourmay not be obvious. referredto in this paper and other birds nestingin the same Rohwer(1986) discussedwhether adoption is just misdir- field. ectedparental care not costlyenough to be selectedagainst Observationsof Lapwing behaviour were carried out (maladaptiveview), or a resultof naturalselection (adaptive daily between 08:00 and 15:30 from hides or a car at the view). In the latter case, replacementscould gain future perimeterof the fields,by watchingindividual birds continu- matingbenefits by increasingtheir breedingexperience, get ouslyfor standardperiods of 20 minutesthrough 15-45•-> tel- accessto limited resources,or increasethe probabilityof re- escopesand binoculars. Nests were foundduring the obser- matingwith the femaleby demonstratingtheir parental abil- vation bouts, or at other times by regularly searchingthe ity to her. Meek & Robertson(1991) pointedout that obser- fields visually for incubating birds. All observationsof vationsof broodadoption often lack quantitativeinformation copulationswere recorded,including those seen outside the aboutpaternal care, and arguedthat it is importantto distin- standardobservation periods. guishbetween full andpartial adoption based on the amount of care that is provided. Further they suggestedthat confi- RESULTS denceof paternityin somecases may play a role when re- placementmales are providing parental care. If so, what Male No. 30 (M30), who was mated to females Nos 22 and looks like full brood adoptionactually differs little from 27 (F22, F27), disappearedpermanently from the field on 30 normalpaternal care. or 31 March 1998. Subsequentlytwo neighbouringmales, Here we report a caseof mate replacementand apparent M36 andM34, eachtook over half the territoryof M30 along broodadoption in two maleLapwings Vanellus vanellus who with F22 and F27, respectively.Figure 2 showsthe phenol- took over the matesof a bigamousneighbour that was killed ogy of events,and the details were as follows: by a predatorat the onsetof his mates' egg-laying.Subse- M30 was unmateduntil 23 March, when F22 (primary quent observationsof the replacementmales may indicate female) appearedand settledon his territory. On 25 March, that their behaviourreflected confidence of paternity. F27 (secondaryfemale) was also present.M30 was seen copulatingwith F27 on 30 March,just a few hoursbefore he METHODS disappeared.He was last seenin the afternoonof 30 March. Feathersof a depredatedmale Lapwing, that we assumewas We studiedthe breedingbehaviour of Lapwingsin two grass M30, were found on a field about 150 m from his territory fields at Gimramyra, Sola, Southwest Norway, in spring at about14:00 the next day. On the dayM30 disappeared,the *Correspondingauthor. 55 Bulletin 95 August 2001 56 Wader Study Group Bulletin F40 / / / / F22 M36 ! ß F43 ! I F27 ! M30 M32 t / F24 M33 F13 ß F26 F20 F25 F21 M31 ß I I 100 rn Figure 1. Map showing the Lapwing territories where mate replacement was observed and other territories on the same field. Territory borders are indicated by solid lines and the number of the defending male (M) is presented within each territory.The broken line indicates the border of the area defended by the replaced male. Nest placement is shown by solid dots and the number of the associated female (F). A road (grey-scale line) runs along one edge of the field, but otherwise it is surrounded by other farmland. primary female (F22) had alreadylaid oneegg, while his sec- actedindifferently towardsthe eggsof F27 (Table 1), and ondary female (F27) was still in her pre-laying period. was never seenon this nestat othertimes of sporadicobser- By 31 March, the males M34 and M36, which held terri- vations. His total incubation effort was not lower than that tories on opposite sides of M30's territory, had divided of M36, however, as he spent39.6% of the time incubating M30's territoryas well ashis two matesbetween themselves. the clutches of his other two females. M34, who was already mated to two females, adoptedF27 Althoughhe died before mostof the eggswere laid, it is as his tertiary female, while M36 took over F22 to become possiblethat all eggsin bothclutches were fertilized by M30, his secondaryfemale. becausefemale birds are ableto storesperm for severaldays On 3 April, the nest of F22 contained3 eggs and, on 6 (Birkhead & M011er1992). The possibility,however, that April, 4 eggs.All four eggshatched on 2 May and all chicks someeggs had been fertilised by M34, M36 or other males were presenton 10 May, when they were checkedfor the last cannotbe discountedbecause no information on paternity time. F22 and M36 were seencopulating once, on 21 April. exists from the studied nests. In comparison,we observedtwo copulationswith his pri- mary female during the sameperiod (20 March-21 April). DISCUSSION M36 took part in the incubationon the nest of F22 as well as on that of his primary female (Table 1). As far aswe are aware,this is the first reportof male replace- On 31 March, M34 attemptedto copulatewith F27 twice mentand apparentbrood adoption in any shorebird.The two during 20 secondsat 12:35, but she refusedboth times. At male Lapwings clearly differed in the parental behaviour 12:43 the sameday, anotherneighbour (M32) attemptedto they exhibited towards the clutchesof their new females. copulate with her, but also in this case she refused. He re- However, as male incubation contribution in this species spondedby peckingat her and chasingher into the air. Then rangesfrom 0 to 90%, with an averageof about30% (Liker M36 attackedM32, and the copulationattempt turned into & Sz•kely 1999, own unpublisheddata), the two males' in- a territory dispute. cubationcontributions did not differ from the normalpattern. The nest of F27 was found containing two eggs on 3 There are at least two types of potential costsincurred by April, and four eggs on 6 April, suggestingthat the clutch caring for the offspring of other males: (1) reducedtime to was completedon 5 April. At 11:45 and 12:00, on 5 April, court other females and (2) reduced time to care for own M34 madethree attempts to copulatewith F27 duringabout offspring in other nests. We suggestthe following three 20 seconds,but wasrejected each time. At 10:30 on 21 April, hypothesesfor the behaviourof the replacementmale Lap- M34 flew over to F27 andtried to copulatewith her, but she wings: refused.The nestbecame heavily sprayedwith manureon 28 April and was subsequentlydeserted by F27. (1) Brood adoption was adaptivebecause of future repro- From the disappearanceof M30 until F27 desertedthe ductive benefits to the replacement males (Rohwer nest,no successfulcopulations with M34 were observed.He 1986). Lapwings seemto showrelatively high breeding Bufferin 95 August 2001 Lislevand et aL: Lapwing mate replacement 57 F27 F22 M30 IIIIIIIIIIIIIIIIIIIII IIIIIIIIllll IIIIIIIIIIIIIII IIIIII 20 01 10 20 01 I0 March April May DATE Figure 2. Phenoloõ¾of male 30 and the replacementnests. Periodswhen M30 was a bachelor(Ba), monoõamous(Me) and biõamous (Bi) are indicated,toõether with prelayinõ,eõõ laging,incubation and chickrearinõ periods for the females.The date that male 30 disap- peared is shown by a vertical line. site fidelity, and even mate fidelity (Thompsonet al. (3) Paternal care was contributed in relation to male confi- 1994, Parish& Coulson1998, own unpublisheddata). denceof paternity(Meek & Robertson1991). The fe- Thus,because of a relativelyhigh chanceof meetingthe malethat received help from the male wasseen copulat- female