BREEDING BEHAVIOR

A Lek's Icon The courtship display of a Guianan Cock-of-the. Rock

Famous œor their œabulous plumage but little studied, the unique breeding behavior oœthis most spectacular cotinga is revealed œorthe first time

Pepper W. Trail

of neotropicalbirds whose mem- HEbersCOTINGAS include somecomprise of theafamily most beautiful, most grotesque,most behav- AtlanticOcean •,•o iorally bizarrebirds in the world (Snow, 1982). Like Howard Hughes and Greta Garbo, many cotingasenjoy a paradox- Figure !. The Guianan Cock-of-the-Rock ical notoriety:they are famous,but mys- feeds mosth'on fruit high in the tree-topsof terious. Family members include the - (• '• • Gu•ana neotropical forests. They also consume In- Amazonian Umbrellabird (Cephalop- sects and lizards. So }*'here's the beak? terus ornatus), whose gleaming black i i, Sunname i pompadourmakes it one of the world's .I., I'1• ' D,sputed I I I- most extravagantlyornamcnted birds, ' I '.T?r'tor¾ •f•.•%'•',111 , sightone can barely convince oneself that and the White Bcllbird (Procnias alba), one is lookingat a bird at all (Figure I). which produces,gram for gram, the Fieldstudies conducted over the past five loudest bird sound in the world. Al- yearsat the Raleigh Falls-VoltzbergNa- thoughfamiliar to ornithologistsevery- ture Reserve in Suriname, South Amer- where,they remain little-studied. Threat- StudySite ica, revealthat the matingbehavior of the ened by the devastationof their rain Guianan Cock-of-the-Rock is as elabo- forest habitat, these and other wonderful- rate as its plumage. ly-namedcotingas such as the Screaming The male Guianan Cock-of-the-Rock Piha (Lipaugus vociferans), the Bare- is neitherinvolved in any aspectof nest- necked Fruitcrow (Gymnoderusfoeti- ingor parentalcare nor does it somuch as dus), and the Handsome Fruiteater (Pi- defend food sources or nest sites with or preola formosa), may never receive for females.Instead, males spend virtual- detailed scientific investigation. rescent-orangemales are bedeckedfrom ly all of their time in courtshipdisplay. The most spectacularmember of this their helmet-like crests to their balloon- This courtshipis highly social, being spectacularfamily is theGuianan Cock- ing puff of ruff featherswith an impres- conductedat a denseaggregation of dis- of-the-Rock (Rupicola rupicola). Fluo- sive array of display plumes. At first playingmales called a lek. The clustered

Volume 39, Number 3 235 Certainmales in the displaygroup attract and successfullymate with females, whereasothers fail completely.In 1981, for example,61 malesdefended display territoriesat the lek, but only 26, or 43%, performedmatings, while the top male accountedfor 30% of matingsall by him- self (Figure 7). Why certain malesare preferred remains unknown. Observa- tions of marked (color-banded) individ- ualsreveals that courtshipin the Guianan Cock-of-the-Rockinvolves a prolonged processof samplingpotential matesby females.In the Voltzburgstudy popula- tion, the typical hen GuiananCock-of- the-Rockvisited the lek on six days. Dur- ing this time she visited three different males a total of nine times, but usually mated with only one. y IIE FEMALEGUIANAN Cock-of-the- Figure 2. Thefluorescent orange males with their brilliant helmet-likecrests aimoat glow fit the Rock approachesthe Ick in the leafy greenishjungle gloom.Nearly all male lek specieshave striking adorstmettt.• or ttttttsaaladapta- tions usedsolely to signalfemales. Males .•picallyremain perched above their courtsuntil the subcanopyof the forest, 10 or more me- arri*•al of a female at the lely. ters up, where her dark brown plumage hidesher in thejungle gloom(Figure 8). males glowing orange in the shadowy al malesper year. Duringthis time. more The malesare continuallyalert for female greenlight of the rain forestis a dazzling than 3500 courtshipsequences and 400 arrival and respondto it with a spectacu- and unforgettablesight (Figure 2). matingswere observed.With a singleex- lar "greetingdisplay," which is alsousu- Although the social organizationof ception,all matingswere performedby ally the first signto a field observerthat a males on the lek may appearchaotic, it individuallycolor-banded males, and in femalehas entered the Ick. The normally is, in fact, rigidly structured.Each male approximatelyone-third of the cases,the silentmales burst into ringingchoruses of defendshis own small display territory female was banded as well. raucous,crowing calls and drop from (Trail, 1985A). The display area is cen- Like other birds with lek mating sys- theirresting perches ( 1-2 metersfrom the tered on a cleared "court" on the forest tems, suchas the Sage Grouse(Centro- ground)down onto their courts. After hit- floor (Figure3). Thesecourts rarely mea- cercusurophasianus) (Wiley, 1973), and ting the groundwith a thump,each male sure more than I-2 meters wide and in- the White-bearded Manakin (Manacus stands erect and violcntl5 beats his clude the adjacent defended perches. manacus) (Lill, 19741, the Guianan wings, flashing the dramatic, usually They containno food or other resources Cock-of-the-Rockis highly polygynous. concealed, black and white primary needed by females. The species' lek servessimply as the rendezvouswhere the sexes meet and mate. Followingmating, femalesnest unaid- ed and, exceptfor randomencounters at the fruit treeswhere both sexes feed, they do not interact with males again until their next breeding attempt. Nests are placed in rocky areas where caves and cleftsprovide shelter for the massivemud constructions(Figures 4 and 5). Protect- ed from the weather, these nests are reusedfrom year-to-year.Any necessary repairsare madeby the femalewith mud andvegetable fibers in the weeksprior to breeding(Figure 6). Not until this study was the complete sequenceof courtshipbehavior in the Guianan Cock-of-the-Rock known. Tan- talizing fragmentary descriptionshad, however, been previously published (Gilliard, 1962, Snow, 1971). The fol- lowingaccount is basedon morethan 24 Figure3. Uponarrival of thefemale. the male Guianan Cock-of-the-Rock lands on his court with monthsof field work over five breeding a loudsquawk and begins his greeting diaplay -- violentlybeating his wings and emitting seasonsat a lek thataveraged 55 territori- resound#tgraucous calls.

236 American Birds, Fall 1985 Figures4 and5. Theauthor (bottom of photos) prowdes the scale by which to measure thecliff face. Nests are concealed inor onrock clefts and in high caves, where they are protectedfrom the weather and reusable from year-to-year. The cock-of-the-rock is a somewhatsocial nester so that sometimes nests are builtwithin a few yardsof each otheron the samerock face. feathers(Figures 9 and 10). In additionto male. She lands on one of his defended tent: the crest fully expands, the chest being a real show-stopper,this wing- perches, 1.5 meters or less above the thrustsout, the filamentous fringes on the beating blows loose debris from the ground,thereby initiating a courtshipvis- secondarywing covertsdeploy, and the court,clearing the surfacefor thecoming it (Figures I l and 12). She has, at least puff of rumpfeathers fluffs out into a soft displaybout. The greetingdisplay may temporarily,restricted her courtship sam- and inviting cushion.An importantfea- involve a seriesof one or more flights pling to a particularmale by enteringhis ture of thisdisplay is that the male keeps betweenperches and the ground,accom- breedingterritory. his back turned to the female at all times. paniedby wing-beatingand loudchorus- The subdued nature of the Guianan This presentshis wing fringefeathers and ing. This vocalizationis audiblefor 100- Cock-of-the-Rockpre-copulation period rump puff to their best advantage.The 200 meters. Additional females ot•en contrastssharply with the wild calling male remains silent and motionless in this arrive within the next few minutes. andwing-beating of the greetingdisplay. posture,only occasionallygiving short The pandemoniumof the greetingdis- Males hunker down on their courts, vertical hops, rapid glancesback at the play usually lastsfrom one to five min- crouch low on their tarsi, and often rest female, and brief mutteredgrunts when utes, although it may continue much their chestson the ground. The male's the tension becomes unbearable. longer early in the breedingseason or displayplumage erects to its greatestex- Fromher low "stand-off'position, the when a large group of females (four or more)arrives simultaneously. As thevio- lent activity dies down, femalesmove to low perchesclose to the males' ground courts. Now the males assumethe static, crouchedposture of full courtshipdis- play. From perches2-6 metersup, the female Guianan Cocks-of-the-Rock are ableto surveythe displayof manyof the densely-clusteredmales simultaneously, without"committing themselves" by en- teringan individualmale's territory. The easeof suchscanning may be an impor- tantbenefit gained by the femalesof lek- breedingspecies. Scanning is energyef- ficient as it eliminates the need to travel betweenwidely-spaced males before se- lecting a mate. Eventually,often after repeated chases by both territorial and non-territorial Figure 6. The massivemud and vegetablefiber constructionholds a clutchof one or two eggs. males,the hen moveslow enoughto en- Theseare a pale brownor buffground color with lilac-gray blotches and spots overlaid with olive ter the defendedterritory of a specific brown.

Volume39, Number3 237 PERCENT OF TOTAL

1o :#111,,,,......

•IT•IAL I• Figure 7. Mating distributionat the Voltzbergstudy lek. 1981. The bars representthe percent of total matings(N= 138 matings)performed by each territorial male on the lek (N=61 males). Thir,ty-fi'veterritorial males(57%) did not mateat all in 1981.And onemale wasresponsible for an astounding30% of all matings. femalemay now hop down ontothe court exact function of this oddly-touching itself, initiating a ground visit and creat- tactile perceptionis uncertain. Does it ing the opportunityfor close-rangeinter- testthe male's ability to maintainhis rig- actionswith the displayingmale (Figure id display posture?Does it enable a fe- 13). Ground visits vary in durationfrom male to overcome her intimidation or fear little more than a second to more than two of the normallyaggressive male? Or does Figure9. Duringthe greeting displa_,; a male minutes,although visits longer than 30- it signalthe male that the female is ready cock-of-the-rockmay fly backand forth be- 40 seconds are unusual. Since the dis- to mate? This physicalcontact between t•een one of his defendedperches and the ground several times. playingmale is alreadyfacing away from the male and female before mating ap- the female, she typically lands behind pearsto synchronizethe pair for copula- adolescentyearlings are blotchyin ap- him. If she happensto land in front ol tion. However, it is not alwaysrequired: pearance,awkward, and erraticin behav- him or to the side, he quickly swivelsto a significant number of matings occur ior (Figure15). Althoughthey never at- faceaway again. If possible,he erectshis without any preliminarytouching. tempt to defend display territories, plumage still further and maintainshis Duringher presence on a male'sterri- yearlingsregularly practice courtship be- postureeven more rigidly (Figure 14). tory,a femaleperforms a seriesof short havior, sometimes toward females, but This new. pre-copulatory phase of groundvisits, hopping back and forth be- even more frequentlytoward crouching courtshipusually involves a fascinating tweenstand-off perches and the court. adult males. They even mount adult physicalprobing of male by female. She males(Figure 16), who are remarkably hops warily forward and touches the tolerantof the yearlings,possibly owing motionlessmale, either restingher chest DsV• complications10%OF^I•I• arecourtship introduced epi- to the strongselection pressure on males in the pillow of his rump ruff or pecking by the bumbling arrival of a year-old to maintainthe rigid courtshipcrouch. at his rumpand wing fringe feathers.The male cock-of-the-rock.These typically

Figure I0. Theblack and whiteprimao'feath- ers, hardly evidentwhen the male ts at rest. add even more fiamboyaneeto the males' greetmg display. The violent wing-beating also .•ert•s to blow loose debris from the Figure8. Hiddenin thejungle canopy, the female is ableto surveythe denseIv clustered males court.Pepper M. Trail. copyright¸ National beforeselecting an individualmale GeographicSociety

238 American Birds, Fall 1985 Figure13. Afemale pays a groundvisit to a particularmale. In response,he erects his plumage still further and maintainshis rigid posturefacing away.from her.

glancingover his backat her. Becausehe lently, breaking free within a few sec- is facingaway from the female,the male onds. The female Guianan Cock-of-the- mustcircle completely around in orderto Rock is quite capable of avoiding mount, and the female often flushes dur- unsolicitedmatings, thereby exercising Figure 11. Thefemale mayvisit several males ing the male'sapproach. These attempt- control over her choice of a mate. at the lek, but usuallymates with onlyone. ed mountsand otherpre-copulatory be- Copulationusually occurs on thecourt haviorsstimulate nearby males to beat itself (Figure 17), althoughit may take The yearlings'misdirected courtship be- their wings and give distinctivescream- place at a low stand-offperch. Mating haviorfrequently disrupts, and occasion- ing vocalizations,the "copulationalert typicallylasts 10-15 seconds,and is con- ally even terminates,female courtship call." Thesepiercing calls appearto be summatedwith vigorouswing-beating with a particularmale. Courtshipvisits threatbehaviors, sometimes flushing the andthrusting by the male. It is accompa- are also frequentlydisrupted by threat femalefrom the court, and functioning as niedby the shrillchorus of "copulation displays,displacements, or directattacks a low risk meansof interferingwith the alertcalls" from the mating male's neigh- on the female(or the displayingmale) by final courtshipstages. If the female re- bors, which may attractthe attentionof adult males, in most cases territorial mainson the courtdespite the hopsand otherfemales in the area, and unques- neighbors(Trail, 1985B). short feints of her male and the calls and tionably attractsthe attentionof the re- If thesedisruptions are avoided,or at wing-beatingof his neighbors,she is searcher.The female usuallyterminates least contained,pre-copulatory interac- probablyready for copulation. the matingby hoppingout from beneath tions between the male and female con- The female Guianan Cock-of-the- themale and moving to a stand-offperch tinue. After a female has remained on his Rock must cooperatefor copulationto to preen. About one-half of the females courtfor longerthan 15-20 seconds,the occur.When males attempt forced copu- returnfor a secondmating before laying male usuallybegins to makesmall hops, lationwith visitingfemales, seizing and their one or two egg clutches,typically grapplingwith themwhile attemptingto returningto the same male unlesstheir mount,the femalesalways struggle vio- first mating was disrupted.

Figure 12. A female initiatesa courtshipvisit by landingon a defendedperch. The malesin the immediatearea of the arena respondby turningtheir backsand crouchingin a rigid displayposture. In contrastto the greeting Figure14. Duringa groundvisit, the female may peck at themotionless male's wing fringe or rest display, males will remain almost silent and her chestin his rumpruff. Whatpurpose this servesis not clear,and copulationoften occurs motionlessthroughout this phase of courtship. withoutthis preliminary touching.

Volume 39, Number 3 239 ACKNOWLEDGEMENTS This research would not have been possiblewithout the cooperationand lo- gistical supportof the SurinameForest Service and STINASU, The Foundation for Nature Preservation in Suriname. I thank all my Surinamefriends, and espe- cially Hank and Judi Reichart,for their unfailing help and hospitalityover the years. Invaluable contributionsto data collectionand sanitymaintenance at the Voltzberg were made by Denis Clark, Greg Farley, Kurt Fristrup,Liz Kellog, Brian McCafiery, Debbie Smith, and Gary Tabor. To themall, a toast:the cus- tomary rum and Ovaltine. Steve Emlen sparkedmy interestin matingsystems, Figure 15 f left). Thoughbumbling male year- and providedadvice and encouragement lings have no lek territory of their own, they throughoutthe work. Finally, I thankDe- frequentlydisrupt the lek and add to the gen- bra Koutnik, who looked at thousandsof eral chaosby practicing courtshipbehaviorß rejectedslides and readthousands of re- Figure 16 (above)ßOlder male cock-of-the- jected words, for her limitlesspatience, rock are remarkablytolerant of theyearlings, care, and insight. who. confused,often mount males as well as Financialsupport was providedby the females in their attemptsto mateß National Science Foundation (BNS 79- Oncefemales lay theireggs, they do !iger), the CrimsonFruitcrow (Haemato- 11231), the National GeographicSoci- not returnto the lek until they are ready derusmilitaris), andthe Purple-breasted ety, the Henry Fund of the National for anothernesting attempt. Meanwhile, Cotinga (Cotinga cotinga) are fascinat- Academyof Sciences,the GeorgeHarris the malescontinue their display,cease- ing, but they await study. Foundation, the Frank ChapmanFund, lesslyadvertising for sexualparmers. The cotingasare primarilyfruit-eaters and Sigma Xi. Asfar asis known. the social complex- and are dependentupon large areasof ity of the courtshipof theGuianan Cock- undisturbedjungle in which to forage. LITERATURE CITED of-the-Rockis the mostextreme of any Neotropicalforests are especially vulner- cotinga.Even the closely-related Andean able to man's acceleratingdestruction. GILLlARD, E.T. !962. On the breedingbe- Cock-of-the-Rock(Rupicola peruviana), With the large-scalealteration of these havior of the cock-of-the-rock(Aves, Ru- doesnot form suchlarge leks and does forests,the ancestraldisplay arenas of picola rupicola). Bull. Amer. Mus. Nat. Hist. 124: 31-68. not seemto haveso rich a pre-copulatory theseand other neotropicallekking spe- LILL, A. 1974. Sexual behavior of the lek- display (Snow, 1982). However, our cies are threatened. Without vast neo- forming White-beardedManakin. Mana- knowledgeis still scanty. Surely the tropicalforest habitat, the beautyand in- cus manacus trinitatus. Z. Tierpsychol. courtshipof suchspectacular, sexually tricacies of these species' courtship 36: 1-36. dimorphic speciesas the Long-wattled wouldpass away, neveragain to astonish SNOW, D.W. 1971. Noteson the biologyof Umbrellabird (Cephalopterus pendu- and delightus. the cock-of-the-rock,Rupicola rupicola. J. Ornith. 112: 323-333. SNOW, D.W. 1982. The Cotingas.Cornell University Press,Ithaca, N.Y TRAIL, P.W. 1985A. Territoriality and dominancein the lek-breedingGuianan Cock-of-the-Rock. National Geographic Research, Vol. I: !12-123. ß 1985B. Courtshipdisruption modifies mate choice in a lek-breedingbird. Sci- ence 227: 778-780. WILEY. R.H. 1973. TerritorialiWand non- random mating in SageGrouse, Centro- cercusurophasianus. Anita. Behar. Mon- ogr. 6: 87169.

-Departmentof Ornithologyand Mammalogy,California Academy of Sciences, San Francisco, CA 94118ß

Figure 17. Mating lastsabout 10 to 15 secondsand usuallyoccurs on theground. About 50% of thefemales return to matefor a secondtime with the samemale beforelaying their clutches.

240 American Birds, Fall 1985