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Plumage colour and pattern in

P.N. FERNS

School of Biosciences,Cardiff University,PO Box 915, Cardiff CF10 3TL, UK, e-marl: [email protected]. uk

Ferns,P.N. 2003. Plumagecolour and pattern in waders. Study Group Bull. 100: 122-129.

At least 16 of the hypothesesthat have beenproposed to explainthe evolutionof plumagecolour and pattern in birdsmay be applicableto waders- five straightforwardphysical explanations, and the restinvolving some form of communicationbetween . Eight of the latterinvolve communication between different (suchas predator and prey) and the rest involve communication between individuals of the samespecies (such aspotential mates). These hypotheses are reviewed and an additionalone based on socialselection proposed.

INTRODUCTION Tyndall blue is one of the coloursproduced by physical effects.It is alsoreferred to as incoherentRayleigh or Nie At least30 hypotheseshave been proposed to explainadap- scattering,though it is actuallyproduced by coherentinter- tive colorationin (Savalli 1995). The evidenceusually ference (Prum et al. 1998). This involves the reflection of consistsof little more than a few examples,and it is often shorterwavelengths of light by minute air bubblesin the possibleto cite just as many contradictoryones (Baker & feathersand the absorptionof longerwavelengths by under- Parker 1979). We tend to rely on our own judgementabout lying melanindeposits. No wadersshow pure blue but the what constitutes,for example,good camouflage, overlook- Ibidorhynchastruthersii has bluish-grey on the head ing how easyit is to make the facts fit our preconceptions and neck, and the Egyptian Pluvianusaegyptius has (see Fig. 1). Most mammalian and avian predatorshave blue-greywing covertsand tail feathers.These probably owe visionthat is very differentfrom our own,probably better in their colorationto Tyndall effectssince bluish pigments are the case of birds and worse in the case of mammals (Endler extremelyrare in birdfeathers. Iridescence occurs more com- 1978, Jacobs1993, Finger & Burkhardt1994). This makes monlyin waders.For example,it is responsiblefor theglossy it difficult to designgood experimentsto test many of the sheenon the back of many ,the Red-kneed ideasabout coloration, but this shouldnot discourage Dotterel cinctus and Black Himantopus wader workersfrom trying to do so. novaezelandiae,as well as the iridescent blue, green and brown of the mantle and wings in NorthernLapwings and TYPES OF PLUMAGE COLOUR SouthernLapwings V. chilensis.Typically, iridescenceis producedby severalevenly spacedand parallel layersof Plumagecoloration can be producedby physicaleffects as melaningranules, separated by keratin.Light is reflectedby well asby pigments,and there are examples of bothof these the top of eachlayer andthe interactionbetween the refrac- in waders.Melanin is perhapsthe mostfamiliar and wide- tive indexof keratinand the spacingof the layersdetermines spreadpigment occurring in feathers.It is derivedfrom the the colourproduced (Lucas & Stettenheim1972). aminoacid tyrosineand occursin at leasttwo quitediffer- Carotenoidsare the othermain groupof pigmentsfound ent forms- eumelaninand phaeomelanin. Eumelanin is re- widely in feathers.They are responsiblefor a rangeof sponsiblefor the browns,greys and blacksthat are present brightred, orangeand yellow colours.Most of the yellows in at leastsome of thefeathers in nearlyevery species of bird. and reds in wader plumageare producedby phaeomelanin The pigmentoccurs in granulesthat are restricted to the out- (Harrison1965, Lucas & Stettenheim1972). Indeed, the only ermostlayers of the featherkeratin. publishedevidence of carotenoidpigment in the feathersof Phaeomelaninproduces various shades of brown, chest- a wader, refers to an unidentified one responsiblefor the nut and red, includingthe bright red breedingplumage of greenish-yellowwing feathers of theNorthern Jacana many wader species,such as canutus, spinosa(Auber 1957). In waders,therefore, carotenoids are C. alpina, SandpiperC. ferrugineaand Bar- largelyrestricted to the iris, orbitalring, legsand . The tailed Limosa lapponica (Harrison 1965, Lucas & red colourof all of theseareas in oystercatchersHaematopus Stettenheim1972). Severalother species have orange-brown spp.is probablydue to carotenoids. or chestnutareas of feathering that are probably due to phaeomelaninbut in whichthe precise nature of thepigment TYPES OF PLUMAGE PA'I-rERN remainsto be established,e.g. NorthernLapwing vanellus(vent), American Recurvirostraamericana The transitionbetween differently colouredareas of plum- (head and breast),Red-necked Avocet A. novaehollandiae agecan be dividedinto threedifferent types - (i) gradual, (headand neck), BandedStilt Cladorhynchusleucocephalus (ii) abruptand irregular,and (iii) abruptand regular. In the (breast)and many (breast and/or belly). Another caseof a gradualtransition, the colours merge into one another, form of melaninis responsiblefor the yellowishplumage of andit is impossibleto definea preciseborder. For example, manyyoung birds (Lucas & Stettenheim1972) including the the orange-brownneck of the AmericanAvocet fades gradu- chicksof plovers. ally into the white of the rest of the body. Irregular,abrupt

Bulletin 100 April 2003 122 Ferns: Plumage colour and pattern •n waders 123

Fig. 1. Curlewdrawing from Thayer (1909). Althoughthe Curlewdoes have plumagethat is crypticagainst a backgroundof grass, it is possibleto infer that almostany plumagepattern is crypticby presentingthe bird againstan appropriatebackground.

transitionsare not especiallycommon, but are seenin the PHYSICAL FUNCTIONS OF COLOUR AND black wing tips of the Pied AvocetRecurvirostra avosetta, PATTERN and the white wing patches of the White-tailed Plover Vaneflus leucurusand Long-toedLapwing V. crassirostris. Thermoregulation Transitions that are abrupt and regular, i.e. that involve a suddenchange in colour along a straightor smoothlycurv- Dark coloursincrease the absorptionand emission of energy ing borderare commonin waders;for examplemost of the from solarradiation, whilst light onesdecrease it (Campbell head and neck bandsof plovershave bordersof this type. & Norman 1998). For this reason,Fjeldsfi (1977) has sug- Indeed,of the ninefamilies of waders,this type of transition gestedthat the dark dorsalplumage of somechicks from is commonon the headand body of eight of them (Rostra- damphabitats may be an adaptationto fasterwarming in the tulidae, Dromadidae,Haematopodidae, Ibidorhynchidae, sun,whilst the pale dorsalcolours of othersfrom arid envi- ,, Burhinidae (head only) and ronmentsmay protectthem by reflectinglight andheat. Red- ).Only in the largestfamily - the Scolopacidae neckedPhalarope Phalaropus lobatus chicks may be in the - are abrupt,regular borders largely absent(with the excep- former category, and Stone Curlew Burhinus oedicnemus tion of a few eye stripes).The overallpatterns that are sepa- chicks in the latter. rated by bordersof thesetypes may dependsimply on the shapeof a particulararea of the bodythat they highlight, e.g. Physical protection therump, or theymay have a specificshape - notablystripes and lines on the head and wings, and curved bandson the Melaninimproves the resistance of feathersto wearin a wide chin, breastand belly. range of species(Barrowclough & Sibley 1980, Bergman Otherpatterns, including those involving streaks and spots 1982).This probablyexplains why theflight feathersof most cannoteasily be categorisedin the aboveway sincethey do wadersare dark, even when the rest of the plumageis pale, not involve uniform blocksof colour and do not have very e.g. most coursersCursorius spp. In the caseof variegated preciseborders. These patterns are usually associatedwith feathers,the paler edgeswear fasterin waders(Hayman et crypsis. al. 1986).

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Radiation protection WoodcocksScolopax spp. and snipesGallinago spp.pro- vide classicexamples of blendingcoloration in which their Dark colours,especially those produced by melanin,protect mottledplumage makes them virtually invisibleagainst the feathersfrom damagingUV radiationthat might otherwise ground(Darwin 1871). Protectiveresemblance is no more acceleratethe rate of feather wear (Burtt 1978, Hayman et than blendingcoloration in whichthe resemblanceto some al. 1986). Suchwear is especiallylikely in the exposedtips specificfeature of thebackground environment is particularly of the primaries(Burtt 1978, 1986) and so theseare often notable.The resemblanceof WoodcockScolopax rusticola protectedby heavydeposits of melanin,and there is usually plumageto deadleaves, sticks and otherground vegetation a slightdecrease in the amountof melaninproximally, e.g. (Thayer 1909, McKelvie 1986), andRinged Plover Charad- mostlapwings and ploversof the genusVanellus. rius hiaticula plumageto stones(Cott 1940) are examples. The Ringed Plover is a classiccase of disruptivecamou- Sighting lines flage, with both the chick andthe adult cited (Thayer 1909, Cott 1938), and drawingsof the chick featuringin the clas- It has been suggestedthat eye stripes,with their sharpbor- sic work on animal coloration(Cott 1940). Both have black ders,can act as sightlines and henceimprove the accuracy and white bands acrossthe neck, with abrupt and regular with which birds can strike at mobile prey (Ficken & Wil- borders,that visually separatethe head from the body and mott, 1968, Ficken et al., 1971). In wadersthis is mostlikely thereforebreak up the familiar bird shape.However, for the to be of valueto ploversand many of themdo haveconspicu- chicksat least,this functionalinterpretation is disputedby ouseye stripes.However, Graul (1973) thoughtit unlikely Fjeldsfi(1977), simplybecause the neck is hiddenwhen dan- thatthis was the explanation for theirpresence in thisgroup. ger threatensand the chick crouches.On the basisof a com- parativeanalysis of adult plovers,Graul (1973) concluded Glare reduction that the mostlikely explanationof their headand breast pat- ternswas that they were indeeddisruptive. The latter study Light colouredplumage near the eye couldcause glare and treated speciesas independentdata points, and therefore thus interferewith vision, leadingto an advantagefor dark really needsrepeating using modern comparative methods. plumagein thisarea (Ficken et al. 1971,Burtt, 1984, 1986). Byrkjedal & Thompson(1998) pointedout that tundra Whilst many wadersdo have the eye surroundedby dark ploverspossess sharply contrasting black and white breed- feathersthere may be otherreasons for this (seebelow), and ingplumage that may serve to breakup thecharacteristic bird severalspecies that forage in habitatswith plenty of glare shapeagainst a backgroundof lichencovered tundra or alpine have white headplumage, e.g. BandedStilt Cladorhynchus habitat. American Golden Plovers Pluvialis dominica nest- leucocephalus,Long-toed and Calidris ing on suchareas suffer lower rates of predationthan do alba. those nesting on more uniform backgrounds(Byrkjedal 1989). This doesnot necessarilyconflict with the view that FUNCTIONS OF COLOUR AND PATTERN INVOLV- the dorsalbreeding plumage of the genus,and of many other ING INTERSPECIFIC COMMUNICATION waders,is crypticagainst similar backgrounds (Darwin 1871, Cott 1964). Crypsis The eye is a conspicuousfeature of birdsand its charac- teristicoutline is oftendisrupted by beingincluded in a dark Camouflageallows an animal to avoid communicatingits striperunning from beakto neck,e.g. Whimbrel Numenius presenceto predatorsand prey. It canbe dividedinto several phaeopus,or from oneeye to theother, e.g. Scol- categories- countershading,blending, protectiveresem- opaxrusticola, Ringed Plover (Cott 1964). The patternsof blance and disruptivecoloration. Woodcock,Ruddy Arenaria interpresand Kill- Most wadersshow countershadingto someextent, i.e. deer Charadriusvociferus have all been cited as furtherex- they are generallydarker on the back than they are on the amplesof disruptivecamouflage (Cott 1940, 1964).The fact undersides,with a gradualtransition between the two. This that woodcockis cited as an exampleof so many different compensatesfor the greaterillumination to whichthe back formsof camouflageillustrates the difficulty of definingthe is subjected,supposedly making the bird more uniform in varioustypes precisely. tone and allowing it to blend more easily with its back- ground. The winter plumagesof the GreenshankTringa Aposematism nebularia, Catoptrophussemipalmatus and tattlers Heteroscelusspp. all providegood examples. Such counter- Someforms of conspicuouscoloration, involving sharp bor- shadingis habitatdependent, being reduced in birdswhere ders and bright contrastingcolours, may serve to warn the groundis highly reflective,and consequentlythe under- experiencedpredators of distastefulnessor otherdanger. For sidesare well lit (Herfin 1976). This may be the explanation example,some brightly markedwaders such as the Red- of the reducedcountershading shown by somedesert dwell- wattledLapwing Vanellus indicus and have ing coursersCusorius spp. beenjudged to be distasteful(to a tigercub and man respec- Completely white undersidescan contribute to more tively), andothers such as the NorthernLapwing and Eura- efficient foraging. paintedblack underneathcatch sianOystercatcher Haematopus ostralegus mildly distaste- lessefficiently becausethe fish seethem sooner(G0tmark ful (to man) (informationcited in Cott 1947). Moreover,the 1987), andthe samemight be trueof waderswith someprey. BlacksmithPlover Vanellusarmatus has been observed giv- CommonRedshanks totanushave been shown to de- ing an aposematicdisplay in whichthe bird reactedto a fast pressthe surfaceactivity of Corophium(Selman & Goss- low approachby a LannerFalcon Falco biarmicusby fac- Custard1988), but it remainsto be determinedwhether being ingit with its wingspartly spread and calling loudly (Thomas white underneath reduces such disturbance. 1983). The suggestionwas that this ploverwas distasteful.

Bulletin 100 April 2003 Ferns: Plumage colour and pattern in waders 125

However, the Blacksmith Plover's wing spursprovide a and young. The broken wing trick, rodent run, incubation more obvioussource of dangerto an attacker. feigningand the fly-away trick (Simmons1985) all fall into this category.It is conceivablethat particularlyconspicuous Mullerian mimicry partsof the plumage,e.g. white rumpsand wing bars,might have evolvedfor this reason- they are certainlydisplayed Similarcoloration may be sharedby morethan one aposem- to goodeffect during some of thesedistraction displays - but, atic species,and this minimiseslosses to naive predatorsas of course,each speciesmay simplybe taking advantageof they learn to avoid distastefulor dangerousprey. All four of conspicuouscolours and patternsevolved for other reasons. the African speciesof Vanelluswith wing spursshare bold black andwhite markings(e.g. Fig. 3d), andthis could con- FUNCTIONS OF COLOUR AND PATTERN INVOLV- ceivablybe an unrecognisedexample of Mullerian mimicry. ING INTRASPECIFIC COMMUNICATION

Batesian mimicry Aggressive mimicry

Non-distastefulor non-dangerousspecies may mimic apo- Animalsmay mimic potentialhosts or prey to facilitatepara- sematicones. There are no completelyconvincing wader ex- sitism, , or to gain some other advantage.Male amplesunless Batesian mimicry is deemedto includemim- Buff-breastedSandpipers Tryngites subruficollis closely re- icry of any unpalatableorganism (e.g. Edmunds1974), in semblefemales (unusual in a lekking species),perhaps be- whichcase it canbe regardedas including mimicry of leaves causethis allows them to disruptmating pairs more easily and dead branches,and thereforeoverlaps with protective and obtainsneaky mating opportunities (Myers 1979). Sat- resemblance.Eight of the 11 African breeding speciesof ellite Ruffs Philomachuspugnax do not mimic females but Vanellus have bold black and white marks. Half of these lack have lessbright breedingplumage than other malesand to wing spursand it is conceivablethat they are Batesianmim- someextent kleptoparasitise the mating opportunities afforded ics of the others.However, they may havebony wing knobs by othermales' breedingterritories at leks (van Rhijn 1991). or just be aposematicdistasteful species. Deimatic behaviour Coloursand patterns designed to attractmates or increasethe Predatorsmay be put off by some form of shockor flash likelihood of obtainingthem throughsuccess in intrasexual colorationor by an intimidatory display that is suddenly competitionare both includedwithin the sphereof sexual revealedwhen a feeding,roosting or incubatingbird is dis- selection.For example,it hasbeen suggested that the silvery turbed. For example, the Willet displaysits conspicuous white tips of the undersidesof the tail feathersof all five underwingpattern when it lifts its wingsprior to takingflight speciesof woodcocksmay be used in courtship(Davison (Baker & Parker 1979). 1976), and may thus be a consequenceof sexual selection. Great males at leks with more white in their tails are Deflective coloration apparentlymore attractiveto females(H6glund & Lundberg 1987, H6glund et al. 1990, but seealso S•etheret al. 2000). Somemarks and displays may deflectattacks towards harm- Wood SandpipersTringa glareola andother waders display lessor lessharmful areasof the body. Brooke (1998) sug- their white rumpstowards rivals duringaggressive encoun- geststhat this is an unlikely explanationof flash marks in ters (Chojnacki& Stawarczyk1981). waderssince they are not obviouslylocated at the lessvul- Piersma & Jukema (1993) have suggesteda very good nerableextremities. However, the tips of the outertail feath- reasonwhy it wouldbe advantageousfor Bar-tailedGodwits ers arejust sucha location,and Forbe's Plover Charadrius to selectbreeding partners with the spectacularbright red forbesi,Killdeer, Common hypoleucos and breedingplumage exhibited by this species.These feathers snipesdo have conspicuousmarks situated there. appear during a moult that takes place on the northward migrationto thebreeding grounds. Although the cost of pro- Pursuit deterrance ducingthe feathersis small, someindividuals of low body massare apparentlyunable to afford it becauseof the simul- Somemarks and displays may be usedto attractthe attention taneousneed to storereserves for the migrationitself. Thus of predators,but to discourageattack, and perhapsdirect it bright red individualsencountered on the breedinggrounds towardsless fit individuals.The white rumpsand wing bars demonstrateboth a soundmigration strategy and efficient of wadersmay fall into this category,e.g. Red Knot (Baker foragingduring the courseof it. If migrationstrategy has any & Parker 1979). geneticbasis (as it doesin speciessuch as BlackcapsSylvia Unpredictablebehaviour may make it more difficult for atricapilla), red individuals demonstratethat they possess predatorsto catchprey. The jinking flight of snipesand some good genesin this respect.Efficient foragingmight allow sandpipersprobably falls into thiscategory (Piersma 1996a). more time to be devotedto parentalduties and thereforebe This behaviouroccurs mainly in speciesthat both rely on of directbenefit to thosechoosing red mates(Hoelzer 1989). cryptic plumageto avoid detection,and flush late; conse- Hasson(1991) suggestedthat feather decorations, such as quentlythey may needto take pre-emptiveevasive action. spots,notches and differently colouredtips could act as amplifiers of feather wear and damage. For example, the Pursuit invitation white tail tips of the wear more quickly than colouredones, making the differencebetween high quality Similar marksand displays may be usedto attractpredators, individualswith low ratesof wear, andlow qualityindividu- andinvite attack, thereby diverting attention away from eggs als with high ratesof wear, more apparent.As pointedout

Buffetin 100 April 2003 126 Wader Study Group Bulletin by Fitzpatrick(1998a), suchaccelerated wear is alsoa handi- cap, sinceit constrainsflight. Male Great Snipesoffer only matingopportunities to females,so the benefitof choosing unwomindividuals in this caseis mostlikely to be thatthey offer good genes. It hasbeen suggested that the uniformityof an iridescent colourreflects developmental stability (Fitzpatrick 1998b). This is becauseprecise control of developmentis neededif an individualis to lay downthe melaninlayers with sufficient regularityto producebright iridescent colours. It is possible that a similar argumentcould be appliedto phaeomelanin, but it is lesslikely to apply to eumelanin,since the latter merely requiresa massof pigmentgranules to producean even dark colour. Even better known is the idea that the degreeof asymmetryof a bilaterallysymmetrical character could indicatedevelopmental stability (M011er& Swaddle 1997). Some of the plumagecharacters already discussed, suchas the breastbands of plovers,could play a role in this respect,especially since many of themare displayed in a way Fig. 2. DisplayingLittle Plover Charadriusdubius with flank feath- that make any departurefrom symmetryobvious (Fig. 2). ers erected, showingthe prominenceand symmetryof the head and The advantageof selectingevenly colouredand symmetri- breast bands, as viewed by a potential mate. cal matescould be thatthey have a harmoniousgenome, and one that is more resistantto the disruptionof development throughsuch factors as parasitismand poornutrition. The contrastingneck collar of youngRinged Plovers, Lapwingsand Egyptian Plovers may help in the relocation Social selection of theyoung (Cott 1964,Fjeldsfi 1977), i.e. facilitatethe rec- ognitionof youngwhen providingparental care. It hasalso This form of selectionincludes colour and plumage patterns been suggestedthat individual recognitionof adultscould selectedby a wider rangeof conspecificsthan just sexual evolvethrough frequency dependent selection of plumage partners(West-Eberhard 1983). Suchplumage may serveto patternsif the advantagesof suchrecognition were strong informother individuals of safetyor danger,or helpto estab- enough.Experiments conducted with both breedingand lish rank or territoryownership outside the breedingseason. winteringRuddy Tumstones are consistent with this,though For example, the white tipped outer tail feathers of the do not proveit (Whitfield 1986, 1988). Killdeer and otherwaders emphasise the openedtail that is Anotherfactor that may help to explainthe abundanceof a preludeto movementor departureand therefore may help abrupt,regular borders between blocks of colourin plovers, co-ordinategroup movements and also act as a warningof andtheir rarity in (see earlier, and Fig. 3d-f), is danger(Davison 1976). Wing-raisingin advanceof take-off that they may serveto showup featherdamage and wear. may servea similar function,e.g. in Red Knot (Cott 1964). Suchdamage could occur during feeding, but is mostlikely Any signalsof this sortneed to be of demonstrableben- to be causedduring fights with otherindividuals. Plovers are efit to, and improvethe survivalof, the signalgiver as well equippedwith effectiveweapons in the form of strong,short as the signalreceiver if they are to be producedand main- bills, powerfullegs and in somecases spurs or bonyknobs tainedby socialselection. Brooke (1998) hasargued that this on the wings.Intraspecific encounters are much more likely is true of flocking speciesin which flash marks,especially to leadto featherdamage in ploversthan in sandpipers,since wing bars, are common. The first individuals to take off, the latter have only long, sensitivebills and feet to use as whena terrestrialpredator approaches, benefit by recruiting weapons.On the whole, territoriality and aggression(both other individualsto join them (thus protectingtheir rear), duringthe non-breedingand breeding seasons) are more in- while thosewho respondto the signal,benefit by not remain- tensein ploversthan sandpipers(based on informationin ing behind. Haymanet al., 1986,Piersma 1996a, b). Thisis perhapsbecause Stawaczyk(1984) suggestedthat displaysof the rumpin their shortbills meanthat they can only forageefficiently in wadersserve to reduceaggression between birds feeding areas where other birds have not reduced the surface activ- together,and that speciesfeeding in similar habitatshave ity of prey, andso they investmore effort in keepingintrud- similarrump patterns. For example,those with "Tringa"type ers away. rumpsprefer feeding in the water andthose with "Calidris" The regular borders of the head and breast bands of type rumpsat the water'sedge. There is no doubtthat many ploverseffectively reveal any featherdamage caused during speciesdo displaytheir rumpsduring suchencounters but fighting by becomingirregular. Birds of low statusmay this seemsmuch more consistentwith selfishlyobtaining acquireirregular patterns as they areexcluded from the best personalfeeding space than with signallingspecies identity feedingand roostingplaces through interactions with con- and hopingfor an altruisticresponse. Moreover, they may specifics.Other individualsmay then recogniseand avoid simplyhave inherited a commonrump pattern from a com- them, or take advantageof their patent inferiority. Such mon ancestor.An alternativeexplanation for suchwing bars inferiorindividuals are alsounlikely to makegood breeding and rumppatterns is that they help co-ordinateflock move- partners.This is certainlythe casewith CommonShelducks ments(Potts 1984), allowingtighter tums and thus reducing Tadorna tadorna,in which only thoseindividuals with the predation,or simply allow energysaving flight formations mostimmaculate red breastbands manage to produceany to be maintainedmore easily. survivingyoung (Ferns & Lang in press).

Bulletin 100 April 2003 Ferns: Plumagecolour and pattern in waders 127

Fig.3. Examplesofwaders with abrupt, regular borders between different blocks ofcolour on the head and neck, capable ofrevealing featherdamage incurred during fighting. (a)Eurasian - black chest band, (b) - black head and nape patch, (c)Black-winged StiltHimantopus himantopus- white eye patch, black head and nape, (d) Charadrius morinellus-white eyestripe, throat patch and breast band, (e) Spur-winged Plover Vaneflus spinosus - black crown, throat and chest, (f) Ringed Plover - whiteforehead patch, eye stripe, neck ring and chest. The ofoystercatchers aretheir most formidable weapon, whilst plovers may usetheir beaks, feet and wings. Despite having delicate-looking beaks, both Black-winged and Pied employ them when fighting(Cramp & Simmons1982).

Bulletin 100 April 2003 128 Wader Study Group Bulletin

CONCLUSIONS Blest, A.D. 1957. The function of eyespotpatterns in the lepidoptera. Behaviour 11: 209-256. Experimentaltests of the efficacy of camouflage,most of Brooke, M. de L. 1998. Ecologicalfactors influencing the occurrenceof 'flash marks' in wading birds. Functional Ecol. 12: 339-346. theminvolving birds preying on ,were carried out in Burtt, E.II. 1978. The behavioral significanceof color. Garland STPM the 1950s (Tinbergen 1974). These included testsof the Press,New York, 456 pp. efficacy of blendingcoloration (Kettlewell 1956), counter- Burtt, E.II. 1984. Colour of the uppermandible: an adaptationto reduce shading(Ruiter 1956), protectiveresemblance (Ruiter 1952) reflectance. Anim. Behav. 32: 652-658. and deimatic behaviour (Blest 1957). It is thereforenot sur- Burtt, E.II. 1986. An analysisof physical,and optical aspectsof avian prising that suchideas have becomewidely accepted,and coloration with emphasison wood-warblers.Ornith. Monog. 38: 1- 126. attentionhas turned to new issues.A searchof the expanded Byrkjedal, I. 1989. Nest habitat and nestingsuccess of LesserGolden- ScienceCitation Index from 1991 to the present(>12 years) Plovers. Wilson Bull. 101: 93-96. yielded only two paperson animal camouflage,neither of Byrkjedal, I. & Thompson, D.B.A. 1998. Tundra plovers. T & AD them on birds. Much more attentionhas been paid to con- Poyser, London, 422 pp. spicuouscoloration, including how warning coloration Campbell, G.S. & Norman, J.M. 1998.An introductionto environmental evolved (e.g. Harvey & Paxton 1981), why it is often asso- biophysics.Springer-Verlag, New York, 286 pp. ciatedwith gregariousness(e.g. Gagliardo& Guilford 1993) Chojnacki,I. & Stawarczyk, T. 1988. Wood Sandpipersusing tail-pat- as visual signalin aggressiveencounters. Brit. Birds 81: 466-468. and the complexityof its interactionswith distastefulness Cott, It.B. 1938. Concealingcoloration in animals.Photogr. J. 78: 563- (e.g. Rowe & Guilford 1999). These are not areasin which 578. studiesof wader colorationare likely to be especiallypro- Cott, It.B. 1940. Adaptive coloration in animals. Methuen, London, ductive,though the potentialrole of distastefulnessand wing 508 pp. spursin the conspicuouscoloration of someplovers and lap- Cott, It.B. 1947. The edibility of birds: illustratedby five years' experi- wings remainsintriguing. ments and observations(1941-1946) on the food preferencesof the hornet, cat and man; and consideredwith special reference to the Although sexualselection is currentlyunder intensein- theoriesof adaptivecoloration. Proc. Zool. Soc. Lond. 116: 371-524. vestigation,waders have been a relatively neglectedgroup, Cott, It.B. 1964. Adaptive coloration.In: A new dictionary of birds. (A. with the singleexception of the Great Snipe.This is despite LandsboroughThomson, Ed.) Nelson, London: 139-142. the fact that they furnishsome of the bestknown examples Cramp, S. & Simmons, K.E.L. (eds). 1982. The birds of the Western of marked sexualdimorphism, e.g. and Reeve, of re- Palearctic. Vol. 3. Oxford University Press,Oxford, 913 pp. versed sexual dimorphismin bill length, e.g. (re- Darwin, C. 1871. The descentof man and selection in relation to sex. JohnMurray, London, 693 pp. cently reviewed by Sandercock2001), and of sexualrole Davison, G.W.II. 1976. Functionof the tail patternin game-birds.Brit. reversal,e.g. .The wide variety of plumagecol- Birds 69: 371-372. our andpattern exhibited by wadersmeans that they arewell- Edmunds, M. 1974. Defence in animals.Longman, London, 357 pp. suited to comparativeinvestigations, and as their phylo- Endlet, J.A. 1978. A predator'sview of animal colour patterns.Evol. genetic relationshipsare becomingbetter known, modern Biol. 11: 319-364. comparativemethods can be used(e.g. Sz6kely& Reynolds Ferns, P.N. & Lang, A. In press.The value of immaculatemates: rela- 1995, Sandercock2001). tionshipsbetween plumage quality and breedingsuccess in shelducks. Ethology. Conspicuoussmall marks that remain hidden when a bird Ficken, R.W. & Wilmott, L.B. 1968. Do facial eye-stripesfunction in is feedingare widespreadin birds,yet we have little idea of avian vision? Amer. Midl. Nat. 79: 522-523. their true function. So many explanationshave been pro- Ficken, R.W., Matthiae, P.E. & Ilorwich, R. 1971. Eye marks in ver- posedfor the white rumps,wing bars and tail markingsof tebrates: aids to vision. Science 173: 936-939. waders(deflection marks, interspecific pursuit invitation and Finger, E. & Burkhardt, D. 1994. Biologicalaspects of bird coloration and avian colour vision including ultraviolet range. Vision Res. 34: deterrencesignals, intraspecific social signals), that consid- 1509-1514. erablecare will be requiredin designingexperiments to dis- Fitzpatrick, S. 1998a.Birds' tails as signallingdevices: markings, shape, tinguishbetween them. Nevertheless,it is relatively easyto length and feather quality. Am. Nat. 151: 157-173. both increase and decrease the size of such marks, and the Fitzpatrick, S. 1998b. Colour schemesfor birds: structuralcoloration and fact that wadersboth feed and breed in openhabitats where signalsof quality in feathers.Ann. Zool. Fenn. 35:67-77 their behaviour can be observedclearly, makes them ideal Fields'g,J. 1977. Guide to the youngof Europeanprecocial birds. Skarv candidates for studies intended to reveal the true function of Nature Publications,Denmark, 284 pp. Gagliardo, A. & Guilford, T. 1993. Why do warning-colouredprey live these signals. gregariously?Proc. Roy. Soc. Lond. B 251: 69-74. Giitmark, F. 1987. White underpartsin gulls function as huntingcam- ACKNOWLEDG EM ENTS ouflage. Anita. Behav. 35: 1786-1792. Graul, W.D. 1973. Possible functions of head and breast markings in I am gratefulto HumphreySitters for giving me the oppor- Charadriinae. Wilson Bull. 85: 60-70. tunity to speculateand to AndrasLiker for restrainingsome Ilarrison, C.J. 1965. The chestnut-redmelanin in schizochroicplumages. of my wilder ideas. 107: 106-108. Ilarvey, P.II. & Paxton, R.J. 1981. The evolutionof aposematiccolor- ation. Oikos 37: 391-396. REFERENCES Ilasson, O. 1991. Sexualdisplays as amplifiers:practical examples with an emphasison feather decorations.Behav. Ecol. 2: 189-197. Auber, L. 1957. The distribution of structuralcolours and unusualpig- flayman, P., Marchant, J. & Prater, T. 1986. Shorebirds;an identifi- ments in the class Aves. Ibis 99: 463-476. cation guide to the waders oJ'the world. ChristopherHelm, London, Baker, R.R. & Parker, G.A. 1979. The evolutionof bird coloration.Phil. 412 pp. Trans. Roy. Soc. Lond., Ser. B 287: 63-130. Ilerfin, I. 1976. Animal coloration.London, Hamlyn, 160 pp. Barrowclough, G.F. & Sibley, F.C. 1980. Featherpigmentation and Iloelzer, G.A. 1989. The goodparent process of sexualselection. Anim. abrasion:test of a hypothesis. 97: 881-883. Behav. 38: 1067-1078. Bergman, G. 1982. Why are the wingsof Larusf. fuscusso dark?Ornis Iliiglund, J., Eriksson, M. & Lindell, L.E. 1990. Femalesof the lek- Fenn. 59: 77-83. breedingGreat Snipe, media,prefer maleswith white tails.

Bulletin 100 April 2003 Ferns: Plumage colour and pattern •n waders 129

Anim. Behav. 40: 23-32. Ruiter, L. de 1952. Someexperiments on the camouflageof stick cater- HiJglund,J. & Lundberg, A. 1987. Sexualselection in a monomorphic pillars. Behaviour 4: 222-232. lek-breedingbird: correlatesof male matingsuccess in the great snipe Ruiter, L. de 1956. Countershadingin caterpillars:an analysisof its adap- Gallinago media. Behav. Ecol. Sociobiol. 21: 211-216. tive significance.Archs Nderl. Zool. 11: 285-342. HiJglund,J. & Roberts, J.G.M. 1990. Femalepreferences, male decision S•ether, A.A, Fiske, P., Killils, J.A & Gjul, J.M. 2000. Femalesof the rules and the evolution of leks in the Great Snipe Gallinago media. lekking great snipedo not prefer maleswith whiter tails. Anim. Behav. Anim. Behav. 40: 15-22. 59: 273-280. Jacobs, G.H. 1993. The distributionand nature of colour vision among Sandercock,B.K. 2001. What is the relativeimportance of sexualselec- the mammals. Biol. Rev. 68: 413-471. tion and ecologicalprocesses in the evolutionof sexualdimorphism Kettlewell, H.B.D. 1956. Further selectionexperiments on industrial in monogamousshorebirds. Wader Study Group Bull. 96: 64-70. melanismin the lepidoptera.Heredity 10: 278-301. Sayalii, U.M. 1995. The evolutionof bird colorationand plumageelab- Lucas, A.M. & Stettenheim,P.R. 1972.Avian anatomy.Integument. Part oration. Curt. Ornith. 12: 141-190. H. US GovernmentPrinting Office, Washington:341-750. Selman, J. & Goss-Custard,J.D. 1988. Interferencebetween foraging Lustick, S. 1971. Plumagecolor and energetics.Condor 73: 121-122. RedshankTringa totanus.Anim. Behav. 36: 1542-1544. McKelvie, C.L. 1986. The book of the woodcock.Debrett's Peerage, Sz(•kely,T. & Reynolds,J.D. 1995. Evolutionarytransitions in parental London, 208 pp. care in shorebirds.Proc. Roy. Soc. Lond. B 262: 57-64. M011er, A.P. & Swaddle, J.P. 1997. Asymmetry,developmental stabil- Simmons,K.E.L. 1985. Distractionbehaviour. In: A dictionaryof birds. ity, and evolution.Oxford University Press,Oxford, 291 pp. (B. Campbell & E. Lack Eds) T & AD Poyser,Calton: 144-145. Myers, J.P. 1979. Leks, sex and buff-breastedsandpipers. Am. Birds 33: Stawarczyk, T. 1984. Aggressionand its suppressionin mixed-species 823-825. wader flocks. Ornis Scand. 15: 23-37. Pierstoa, T. 1993. Red breastsas honestsignals of migratoryquality in Thayer, G.H. 1909. Concealing-coloration in the animal kingdom. a long-distancemigrant, the Bar-tailed Godwit. Condor 95: 163-177. Macmillan, New York, 260 pp. Pierstoa, T. 1996a. Family Scolopacidae(sandpipers, and phala- Thomas, D.H. 1983. Aposematic behaviour in the Blacksmith Plover. ropes).In: Handbookof the birds of the world. Vol. 3, (J.D. Hoyo, A. Ostrich 54:51-52. Elliott & J. Sargatal Eds.) Lynx Edicions, Barcelona: 444487. Tinbergen, N. 1974. Curious naturalists. Penguin, Harmondsworth, Pierstoa, T. 1996b. Family Charadriidae(plovers). In: Handbookof the 271 pp. birds of the world. Vol. 3, (J.D. Hoyo, A. Elliott & J. SargatalEds.) Van Rhijn, J.G. 1991. The Ruff. T & AD Poyser,London, 209 pp. Lynx Edicions, Barcelona: 384409. West-Eberhard, M.J. 1983. Sexual selection,social competition,and Potts, W.K. 1984. The chorus-linehypothesis of manoeuvrecoordination speciation.Quart. Rev. Biol. 58: 155-183. in avian flocks. Nature, Lond. 309: 344-345. Whitfield, D.P. 1986. Plumagevariability and territorialityin breeding Prum, R.O., Torres, R.It. Williamson, S. & Dyck, J. 1998. Coherent turnstoneArenaria interpres:status signalling or individual recogni- light scatteringby blue feather barbs.Nature, Lond. 396: 28-29. tion? Anim. Behav. 34: 1371-1482. Rowe, C. & Guilford, T. 1999.Novelty effects in a multimodalwarning Whitfield, D.P. 1988. The socialsignificance of plumagevariability in signal. Anim. Behav. 57: 341-346. wintering turnstoneArenaria interpres.Anim. Behav. 36: 408415.

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