THE AUK:

A QUARTERLY JOURNAL OF

ORNITHOLOGY.

VOL. L. OCTOBER,1933. NO. 4.

THE PROBLEM IN .

BY A. H. CHISHOLM, C. F. A. O. U. (Plate XI.) IT Is an odd fact, and one to be lamented,that Australianshave donelittle sustainedwork amongtheir country'srepresentatives of a very remarkablefamily of , the . This relative failuremay be duein part to economicreasons and to our ex•ensive distances.It may be due alsoto the conmpetitivelure of other extraordinarybirds with whichthis "last, lonecontinent" abounds. As an anomaly,however, I fancy it is due largely to our embar- rassingvariety of cuckoos. Australiacontains no fewerthan .fourteenspecies of thesebirds, rangingfrom robustcreatures as large as pheasantsto beautiful little birds scarcelylarger than sparrows,and all but one are parasitic. Sydneyitself is surelythe mostcuckoo-haunted city in the world,since in any normalspringtime one may seeor hear ninespecies of cuckoosupon its fr•ges, andsome of themocca- sionallynear the centerof the city. I imaginethat i/all these birdsbelonged to onespecies, migratory for preference,they would offer a sharperchallenge to nimble wits. As matters are, their very varietyis disarming;it causesthem to blendunostentatiously with the generalbird-population. However that may be, what watcher of wild birds in Australia wouldcare to think of this continentwithout its cuckoos?They are not, as one may say, neighhourlybirds. They are for the mostpart undistinguishedin form and plumageand flight, and 385 I

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UPPER--WHITE-BROWED SCRUB-WREN FEEDING YOUNG FAN-TAILED CUCKOO. LOWER--I•UFOUS FAN-TAIL FEEDING YOUNG . PHOTOGRAPHEDAT SYDNEY•AUSTRALIA• B1 r A. H. CHISHOLM. 386 CHISHOLM,TheCuckoo Problem in Australia. [•c•t. not one of them couldfairly be termed a songster. Yet there is somethingappealing about theseleathered outcasts: something admirablein the bland defiancethat carriesthem through all tribulationsin a hostileworld and enablesthem to populateevery portionof the continent,from the jungles,forests and heath-lands of the coastalareas to the great lonely spacesof the interior; and, moreover,there is somethingwistful in their voices,which, how- ever irritating whenheard all throughthe night, possessan "airi- ness" that never permits them to becomeprosaic. One shotfid,I think step warily when striving to interpret -voices. It may be sufficientlyobvious that a bird singing heartily, and with every indicationof good cheer, is in fact ex- pressingpleasure; but it doesnot necessarilyfollow that a bird whosecustomary notes fall plaintively upon our hearingis indeed feelingforlorn. And yet, is it not a striking fact, that although the voicesof Australiancuckoos vary so widely, every one of them conveysa strongsuggestion of melancholy? Listento thesewails and trills and screams,and almostyou will be persuadedto believethat the senseof dolouris not merely a human interpretation:that althoughthese may be mating-calls, the cuckooshave acquiredover the centuriessome consciousness of being outcasts,and are expressingvocally the lonelinessof the non-normal.• Listen in particular to the trilling wail of the Fantailed Cuckoofalling through darknessand continuingwith the dire insistence that has caused its author to be termed the "Brain-fever Bird"; or listen to the gaspingnotes of the Brush Cuckooissuing from a jungle at midnight;or, again,listen to the high-pipingmonotone of a BronzeCuckoo emulating the shrilling of a high wind: listen to any or all of thesecries and you cannot avoid the conclusionthat here is Loneliness,utter and inescapable; here, in the voicesof birds, is the spirit of Masefield'sSeekers: "There is no solaceon earth for us, for such as we ." I would not have it thought, however,that every cuckoovoice in Australiais entirely dolorous. The ,for instance, can not be creditedwith melody,but there is a certain heartiness,

• Perhaps there is some evidence here to support the theory of exponents of the theory of territory in bird-life that song is prompted by, or has been developed upon, territorial considerations.--A. H. C. ¾1•L] CHISHOLM,TheCuckoo Prob•m in Australia. 387 perhapsan element of "earthiness"in its curious,throaty, as- cendingcall. This bird is, moreover,a definiteharbinger of spring in southernAustralia, and manypeople who knownothing of its loosedomestic habits are familiarwith and cordiallywelcome the salutation that has caused this cuckoo to be known as the "Scale- Bird." No enterprisingboy who takespart in the Bird Call com- petitionsconducted annually in Sydneywould dream of omitting the chant of the Pallid Cuckoofrom his repertoire. I suspect thispopularity to be duenot somuch to the qualityof the cuckoo's call as to its settingin the chorusof early spring;were the same deliberatewhistle heard only at night it wouldbe votedeerie. Further north, in sub-tropicalareas, the Koel, or Black Cuckoo, is equally persistentas a harbingerof spring, a fact to which Brisbanenewspapers bear witness each September, for they never fail to receivethen, reportsfrom rural areas to the effect that "Last night I heard my first Cooee-Birdfor the season." Here againit is probablethat relativelyfew peopleknow of the bird's domesticmisdeeds; it is the appealingvoice that grips them. The voice of the Koel is indeed one of the most notable of bird- utterances,•ts chief feature a full-throated "Cooeeee" and an equallyresonant "Too-wong"--melodiously contralto calls which by reasonof their vowelstress contain a suggestionof "the moan of dovesin immemorialelms." It has been suggestedthat the distinctivelyAustralian cooee had its origin in the voiceof this bird. Be that as it may, the Koel did in fact furnishthe nameof one of 'slargest metropolitan suburbs, Toowong; for to this localitylong ago the "Cooee-Birds"came abundantly to feedupon cockspur berries, and in the processof tellingtheir name to all the hills,unwittingly contributed a geographicallabel. Voiceagain is the dominatingfactor in the popularrecognition of the Channelbill,which, two feet in length,is easilythe largestof Australiancuckoos. This bird, too, is a migrant,but no harbinger of spring;it drifts down the easterncoast with the comingof summer,and by reasonof its screamingprelude to the heavyrains of the tropicsit is frequentlyknown as the "Storm-Bird." This great bird is, to speakmildly, the least appealingof the cuckoos. One needhave no personalobjection to the deceptionit practices in loistingits familyresponsibilities onto magpiesand Currawongs, 888 CHISHOLM,The Cuckoo Problem in Australia. [oct.[Auk and neednot hold the bird to blamefor its top-heavysuggestion of the hornbills;but one cannotreadily forgiveit that appalling scream,a blusteringoutburst that has not even the savinggrace of revelry.To listento the Channelbillis to mournthe proba- bility that severalyoung magpies, singers in the making,died to make room for this uncouthgiant. Many birds of Australia, as is the casein other countries,are esteemedbecause of their sociability. It will be clear that this doesnot obtain with the cuckoos,even allowingfor the element of wistfulnesswhich I have suggestedis present in the notes of many species. And yet the hand of man, destroyerof so many irreproachablebirds, is rarely raisedagainst a cuckoo. I do not supposethat this freedomfrom molestationis due to the skulking nature of the variousspecies, or even to publicignorance of their murderoustendencies; it is due rather to the fact that cuckoosdo not directly affect man or his products, whereasif they were occasionallyfruit-eaters, like some of the ,or were edible,like the pigeons,they would be much lessabundant than they are. With bird-studentsthe outlook is different. We are impelled at times to give seriousthought to the menace of the cuckoos, recognisingthat their birth-rate implies a commensuratelylarger death-rateamong other insectivorousbirds, and recognisingalso that intenseparasitising may gravely decimatethe numbersof a restricted species. What, for instance,of the Rock-Warbler, a bird found only in the sandstoneareas near Sydney? Is it likely to be endangeredby the ravagesof the Fantailed Cuckoo? suggestthat in such caseswe may well have faith in Nature, realising that even if excessiveattention by cuckoosseriously decimateda species,the consequentshortage of nestswould react against the cuckoosthemselves and causethem to "break in" new fosterers. Realisingthis, we may peepinto a honey-birds'nest and, seeing there an eggslightly different from the others,we may reflectthat here is a murderer in the making, and that both sentimentaland economicinterests would be served by removing this egg and savingthe lives of unbornhoney-birds; but upon further thought (unlesswe be merely egg-collectors),we will not interfere. Full Vol.1933 L]J CHISHOLM,ß TheCuckoo Problem in Australia. 389 often, too, we may comeupon a robustyoung cuckoo luxuriating in a flycatchers'nest, the bodiesof the baby flycatcherscold in deathbelow, and the misguidedfoster-parents working themselves thin in the interestsof their changeling,and againwe may feel an impulseto right this wrong;but again,if we are discreet,we will set asidethe merelyhuman view and refrain from meddlingin a dramathat is, in plain fact, no concernof ours. Far better to let the uncannyprocess run its course,to mark carefullyand marvel at all developmentsassociated with that menacingegg, and to endcavourto trace throughthese factors the originand historyof avian parasitism. Is there,after all, any need to lookfar for the beginning ofthis remarkablehabit? Are not its early stagessuggested by the behaviour of particular birds today? I think here of two Aus- tralian species,widely dissimilar. The Large-billedScrub-Wren, a jungle denizen,consistently lays its eggsin disusednests of the Yellow-throatedScrub-Wren; I have found eggsunder thesecir- cumstanceson many occasions,and have only twice seenthe real nest of the Large-bill. Secondly,the Blue-facedHoneyeater has so stronglydeveloped the practiceof re-furnishingold nestsof the Babbler,Magpie-Lark, etc., that its originalnest, a saucer-shaped structure suspendedamong leaves, is rarely found today. What do thesecases imply? Surely the evidencesuggests that in courseof time the Large-billedSernb-Wren and the Blue-faced ,perhaps by reasonof successivegenerations inheriting tendenciestowards nest-stealing, may loseeither the desireor the ability to build nests,thereby beeomlngwholly dependentupon other birds for homes. It must inevitably happen, if the drift extendsthus far, that there will not be sufficientdisused nests to go round, upon which the homelessbirds must either oust other birds or drop their eggsin with other clutches. And once the habit of depositingeggs in occupiednests of otherbirds is developed with someconsistency, surely we are in sight of completepara- sitismI It seemsto me, however,that the origin of parasitismis not the mostappealing problem associated with cuckoos. How muchmore fascinatingis it to study the incidenceof the habit, to mark how thesestrange birds have beentaught to be cautiousby their very 390 C•ISUOLM,The Cuckoo Problem in Australia. [oct.A•k dupes,and to follow the dramatic careerof the youngcuckoo in the nestI Why is it, to begin with, that birds generallyreeoguise the cuckoomenace only up to a certainpoint? When, for instance,a I(oel enters the territory of Friar-Birds, these truculent and noisy honeyeatersattack the cuckooso fiercelythat they some- times beat it to the ground; yet when the I(oel stealsher eggs into Friar-Birds'nests those eggs are contentedlybrooded and the youngI(oels that appearlater are rearedwith thoroughsolicitude. And so it is with other losrefers in relation to other cuckoos. It may be urged, of course,that birds do not reeoguisecuckoos as cuckoos--asborrowers of nests--but attack them merelybecause they are territorial intruders. If this be so, why do many birds fly into a frenzy at the mere call of a cuckooduring the breeding seasonand pay no heed to it at other times? I cannot take this dellcatepoint to any definiteconclusion, my only suggestionbeing that the potentiallosrefers attack cuckoosbecause they reeognise them, in somedegree, as meddlersat nests,without appreciating what that meddlingportends. Followinghard upon the anomaly cited above is the puzzle as to how the intrudingegg is depositedin a nest. This is oneof the mostdebated points in cuckoolore; therehas been much argument aboutit, and the endis not yet. Whateverbe the easein Europe, there can be little doubt that somecuckoos in Australiasit upon the chosennest to lay and othersdeposit the eggwith the beak. Direct depositionis, of course,the "natural" method. I take it that this courseis alwaysfollowed by the large Channelbill,which patronisesthe sturdy,stick nests of crows,magpies and Currawongs, and alsoby the I(oel, whichfayours chiefly the commodious,open nests of friar-birds, orioles and fig-birds. We have, indeed, a record of a Channelbillbeing seento sit upon a nest, and several recordsof I(oels being seen to do likewise; and in each ease the euekoo'segg was subsequentlyfound in the nest. Possiblysome of the smaller cuckoosoccasionally sit upon the nest to lay, but this is a sheerimpossibility in mosteases. I believe, therefore,that as a rule the female cuckoo (of the smallerspecies), inspects the nest in advance,and if it be either too small or too fragile to enter, she lays upon the ground,takes CSOLa, TheC,ekoo rrob. 391 the eggin her beak, fliesquickly to the "marked" nest, clingsto the side or some other convenientsupport, and drops the egg gentlyinto the chamber,after whichshe seizes one of the fosterer's eggsand fliesoff, droppingthe stolenegg as sheflies. There are recordsin Australia of cuckoosbeing shot while carrying eggs-- their own eggs--andof othersleaving eggson the groundwhen disturbed. There appearsto be a popularimpression that cuckoosare lazy and carelessbirds--inconsequential creatures that deposittheir eggsin haphazardfashion and leavethe continuanceof their race to chance. Actually, there is probably more energy,more resolu- tion, and more individualityinvolYed in the exerciseof the para- sitic habit than in the building'of a nest and rearingof young;and as for the chargeof carelessness,you have only to look well into the subjectto realisethat lapsesare relatively few, that they are due almostentirely to stressof circumstance,and that they are in fact calculatedto placea healthycheck upon Cuckoos when the numbers threaten to become too numerous. It will be well, however,not to go to the other extremeand acclaimthe cuckoosfor supposedhigh skill in selection. The credit lies rather with the more intelligent of the fosterers;for thesebirds, by desertingdamaged nests and rejectingunsuitable eggs,have actually "trained" the parasiticbirds to their present skill. Applaud the cuckoosfor their adaptability if you will, sincethey have overcomeall obstaclesto their parasiticprogress, but save a word of commendation for the effective manner in which the little fosterershave applied the pressureof natural selection. It might perhapsbe arguedthat the largenumber of fosterers patronisedby certain Australian cuckoosindicates marked loose- nessin selection;for the Pallid Cuckoohas been shown,on the basisof merely oneegg-collection, to have "borrowed" the nests of no fewer than 81 speciesof birds, the two commonBronze Cuckoos64 specieseach, and the Fantailed Cuckoo43 species. Actually, however,each cuckoo fayours a few particular fosterers, and only whenthe supplyof suchnests falls belowthe demanddo they turn to other kinds. There is a theory, somewhattimidly advanced,that .a female 392 CHISHOLM,TheCuckoo Problem in Australia. [oct.Auk cuckoowill give first choiceto the kind of nest in which sheherself was born. This propositionis hedgedwith difficulties,but it seems to me on the whole a reasonableassumption. Such an action wouldappear to be a natural one--on the part of an "unnatural" bird! What are we to assume,however, in the case of cuckoos which"fluke" their way into this troubledworld in unusualnests? Does it follow that environmentalleanings will cause them to endeavour to make those unusual fosterers less unusual? Suppose,too, that a female Fantailed Cuckooborn in a tobin's nest had for mate a male born in a honeyeater'snest--what then? At a guess,I should say that this would make little difference, sinceit is doubtful (and especiallyso in the light of the suspicion that cuckoosare polyandrousor promiscuous),whether the male exercisesany influenceon the choiceof nest or colour of eggs. Supposeagain that a femaleRobin-Cuckoo mated with a Honey- eater-Cuckoo,A Wren-Cuckoo, and a Flycatcher-Cuckoo,and that each male exercisedsome influence in respectof nestsand eggs--whata pretty tangle the lady would be in! And what a sad waste of all her "inherited training" in the principlesof natural selection! For surely this law would be strained to breaking- point--it couldnot, for instance,achieve harmony in egg-colors-- if it were continuallydisturbed as a result of "mixed marriages" among cuckoos! The late H. L. White, who got together Australia'slargest collectionof birds' eggs,was firmly of opinionthat each speciesof cuckoohas favorite fosterers,that theseare not numerousin any case,and that whenopen nests are usedthere is a broad,and some- times striking, similarity betweenthe egg of the cuckooand that of the regularfosterer. "There is no doubt in my mind," he wrote, "that Australiancuckoos which lay in opennests usually select as foster-parentsthose birds whoseeggs nearly approachtheir own in colouration." He had in his collection scores of clutches that apparently refuted this view, but thesehe describedas "chance" combinations,leaving perhaps90 per cent that harmonised. It is probablethat Mr. White's view was basedlargely on the Pallid Cuckoo, which exhibits a strong preferencefor open nests and which lays a pink egg, so like many honeyeaters'eggs that it is sometimesdifficult to distinguishthem. This, it may be said, Vol.1933 L]J CHISHOLM,TheCuckoo Problem in Australia. 393 is an eloquentinstance of natural selection;the fosterers,being ableto seethe eggs,have gradually eliminated unfavorably colored onesand "trained" the cuckoosto egg-harmony.Why, then, is the color-harmonyequally striking in the caseof the Black-eared Cuckoo,which has only two regularfosterers, the SpeckledWarbler and the Red-throat, both of which build domednests? In each casethe eggof the Black-earedCuckoo, so unusualand attractive in its reddish-browncolour, so closely resembles that of the fosterer that it may be separatedonly by rubbingoff the pigment,which in the fosterers'eggs is ingrainedin the shell. Somefew other points of interestin regardto cuckoos'eggs, with the H. L. White collection as a basis,remain to be stated. The Channelbill(4 fosterers),and the Koel (11 fosterers),patronlse only open nests, and the Black-earedand Chestnut-breasted Cuckoosonly domednests; all other cuckoosuse both openand domednests. Of the 81 fosterersrecorded for the Pallid Cuckoo, however,72 build open nests,including 34 honeyeaters,whereas the Fantailed and BronzeCuckoos show a generalpreference for domednests. The doubtfulhonor of beinghost to s/x speciesof cuckoos(in variousparts of Australia), is held by the Red-backed Wren; severalother birds,notably robins and fantails, have acted from time to time as host to five speciesof cuckoos. In additionto having the largestnumber of dupes,the Pallid Cuckooholds the recordfor extremes,since it rangesfrom nestsswaying perilously in the tree-topsto othersbuilt right on the ground,and, moreover, its egg has been found in the nest of the Magpie-Lark, a bird as largeas a pigeon,and in that of the tiny Emu-Wren,whose body is scarcelymore than two incheslong. An elusivelittle problem,upon which Australianshope to con- centrateshortly, is involvedin the questionas to whetherany femalecuckoo, having found suitablefosterers, takes any further interestin her eggsor youngin the variousnests. I inclineto the view that she does,but only vaguely. Since the cuckoohas no broodingto do, shemight as well exercisevigilance as do nothing; and certainlyshe does "stick around,"for if a nestcontaining a cuckoo'segg is disturbedand a secondone is built, you may look with confidencefor a cuckoo'segg in the new nest. Possiblythere is a hint upon this point to be gainedfrom the fact that there is 394 0ttI•tOLM,The Cuckoo Problem in Australia. loach. usuallymore than oneyoung Channelbill in a crow'sor a magpie's nest. Dr. W. Macgillivray deducesfrom this fact, and marvels accordingly,that the youngcuckoos (while still blind and naked), are able to distinguisheach other and thus eject only their foster- brethren. Surelythis is askingtoo much,even of suchamazing birdsas cuckoos I I wouldprefer to assumethat the adult Channel- bill revisits the nest and carries out the ejections. Indeed, it seemsvery doubtfulif youngChannelbills ever throwout eggsor young under any circumstances.Crows and magpies,unlike smallerbirds, are well able to feed both their own offspringand youngcuckoos, and (againunlike smaller birds) there is room in the nestsfor both:wherefore, it appearsprobable that the infantile "touchiness"has disappearedin this case. Anyway, there are several recordsof fosterersrearing both their own young and Channelbill Cuckoos at the same time. Ejection of eggsor young by blind and naked baby cuckoos of the smallerspecies has, of course,been witnessed on various occasionsin Australia. No one hasseen an adult cuckooassisting in the ejection,and we do not believe(in spite of a European suggestionon the point), that this is ever the case,the baby cuckoosbeing quite well equippedfor fightingtheir own battles. Whether the mother cuckoosassist in the feedinglater is another matter. We have at least one Australiancase of a cuckoobeing seento visit a nestand feeda youngcuckoo, and two soundobserv- ers have given particularsof youngcuckoos that had left the nestbeing fed by adult cuckoosas well as by the fosterers. I am convinced,however, that theseodd casesare merely exceptions that prove a rule, and that the smallercuckoos, at all events, customarilyleave the feedingof their young entirely to other birds. Recentbreeding seasons have beenbountiful ones for cuckoos aboutSydney, due probably to heavyrains and consequentlush- nessof vegetation. We have,in fact, seenso many of thesepara- sitespreying upon other birds from late Augustto late January, that the old questionhas arisenas to whether the cuckoosare worth the mortality they entail. A studentof cuckoosin England suggesteda few yearsago that therewere approximately 1,250,000 cuckoos'eggs laid in the UnitedKingdom each spring, at an average ProVU 395 rate of 10 to eachpair of birds. If this be broadlycorrect, imagine how many cuckoos'eggs are depositedeach year in Australia, with its vastly greater area and twelve more speciesof avlan parasites;and imaginein turn the countlessnumber oœ other birds that arebeing sacrificed every year by the adultcuckoos removing eggsand the infant cuckoosslaughtering nestlingsl On the other hand, however,the cuckooshave a placeoœ their own in natural economybecause oœ their fondnessfor caterpillars. An amazingindication oœ the capacityoœ the parasiticbirds in this respectwas given by a youngBronze Cuckoo which was kept in an orchardin ;this bird, no largerthan a sparrow,ate at onemeal over 300 caterpillarsoœ the codlin-moth(taken from a bandageon a fruit-tree),and it maintainedthe healthyaverage oœ260 to each roeall All •.hlngsconsidered, therefore, it may be that the Cuckoos justify their existenceon an economicbasis; and as for the ethical aspect,even if we wonderwhy Nature developedthe lopsided processof avian parasitism,we need not necessarilyfollow the Englishcurate who madea practiceoœ shooting cuckoos because "they are suchimmoral birdsI" "Daily Telegraph" Sydney,Australia.