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THE A QUARTERLY JOURNAL OF

VOL. 101 JANUARY1984 No. 1

BREEDING AND OF THE (PINGUINUS IMPENNIS): ANECDOTAL EVIDENCE AND CONJECTURES

SVEN-AXEL BENGTSON Museumof Zoology,University of Lund,Helgonavi•en 3, S-223 62 Lund,Sweden

The Garefowl, or Great Auk (Pinguinusimpen- Thus, the sad history of this grand, flightless nis)(Frontispiece), met its final fate in 1844 (or auk has received considerable attention and has shortly thereafter), before anyone versed in often been told. Still, the final episodeof the natural history had endeavoured to study the epilogue deservesto be repeated.Probably al- living in the field. In fact, no naturalist ready before the beginning of the 19th centu- ever reported having met with a Great Auk in ry, the GreatAuk wasgone on the westernside its natural environment, although specimens of the Atlantic, and in Europe it was on the were occasionallykept in captivity for short verge of extinction. The last few pairs were periods of time. For instance, the Danish nat- known to breed on some isolated skerries and uralist Ole Worm (Worm 1655) obtained a live rocks off the southwesternpeninsula of Ice- bird from the and observed it for land. One day between 2 and 5 June 1844, a several months, and Fleming (1824) had the party of Icelanderslanded on Eldey, a stackof opportunity to study a Great Auk that had been volcanic tuff with precipitouscliffs and a flat caught on the island of St. Kilda, Outer Heb- top, now harbouring one of the largestsgan- rides, in 1821. nettles in the world. The men went ashore on Notwithstanding the extremeshortage of de- a sloping ledge and, in Newton's (1861) nar- tailed field observationsof living Great , ration, the following took place: "As the men there are numerouspublished accountsof voy- clamberedup they saw two Garefowls sitting agers having seen and collected the speciesat among numberlessother rock- ( troile seaor on its breeding grounds.Similarly, there and Alca torda), and at once gave chase. The is an abundance of records from archeo- Garefowlsshowed not the slightestdisposition logical excavations, and the total literature to repel the invaders,but immediatelyran along dealing with the Great Auk is truly impressive. under the high cliff, their headserect, their lit- In 1855Professor Japetus Steenstrup published tle somewhatextended. They uttered no the first monograph(in Danish), and exactly30 cry of alarm,and moved,with their shortsteps, yr later Symington Grieve's excellent book, about as quickly as man could walk. Jon "The Great Auk, or Garefowl (Alca impennis, (Brandsson),with outstretched arms, drove one Linn.).Its History,Archeology, and Remains," into a corner, where he soon had it fast. Sig- appearedand wasdedicated to Steenstrup,"the urdr (Islefsson)and Ketil pursued the second, fatherof Garefowlhistory." Another rich source and the former seized it close to the edge of of informationis Naumann's(?03) "Naturge- the rock, here risen to a percipicesome fathoms schichteder V6gel Mitteleuropas," which con- high, the water being directly below it. Ketil tains hundreds of literature references ,to the (Ketilson) then returned to the sloping shelf Great Auk. whence the birds had started, and saw an lying on the lava slab, which he knew to be a • An invited review.--J.A.W. Garefowl's. He took it up, but finding it was The Auk 101: 1-12. January 1984 FRONTISPIECE.Great Auk (Alca impennis).From an engraving in C. B. Cory's "Beautiful and Curious Birds of the World" Part II, February 1881. This engraving was presented to the American Ornithologists' Union by the Nuttall Ornithological Club to commemoratethe latter's centennial celebrationin October 1973. 2 $VEN-AXELBENGTSON [Auk, Vol. 101 broken, he put it down again. Whether there 16th and 17th centuries,probably refer to the was not anotheregg is uncertain.All this took colony on off the east coast of placein much lesstime than it takesto tell it." (see Grieve 1885). Quite possi- Thesewere the lastliving membersof the Great bly it may alsohave bred on other islandsalong Auk ever heard of; later reports of sightings, the east coastof (although see on both sides of the North Atlantic, could nev- Peters and Burleigh 1951), as birds were fre- er be sufficiently documented.The two Eldey quently encounteredon the fishing banks and birds were turned over to a dealer, but the ul- bones have been found as far south as , timate destiny of the skins is unknown. Their althoughnowhere in suchquantities as on Funk bodieswere alsosaved, and someof the organs Island (for a review see Greenway 1958). Un- are still preservedin the collectionsof the Mu- doubtedly the prehistoric distribution was at seum of Zoology at the University of Copen- times much wider (Salmomonsen 1945), but the hagen, the only pickled specimensin exis- exactrange is difficult to evaluatesolely on the tence. basisof findings of bonesin subfossildeposits; Most writers have, quite understandably, being a primarily sea-livingbird, the GreatAuk been preoccupiedby the decline and disap- surely strayed over large areas outside the pearanceof the Great Auk. This paper focuses breeding season. on bits and piecesof information that can be Whether or not the Great Auk bred in Green- used in an effort to draw a picture of its ecol- land cannot be determined, although it is ogy. There is not much reliable first-hand in- claimed to have done so in the 16th century on formation to be found in the literature on any skerriesin the AngmagssalikDistrict (Salmon- aspectof its life history (often none at all), so sen 1967). However, Salmonsen (1950-1951, some speculationis an unavoidable necessity. 1967) may well be correctin suggesting(on the Naturally, many of my conjecturesconcerning basis of various evidence) that the Great Auk the Great Auk's ecology are strongly influ- was a regular visitor along the low-arcticparts encedby what we know to be true of the ecol- of western between Septemberand ogy of the extantspecies of the family Alcidae. January,when mostly younger birds migrated In the final section of the paper, I discussthe northward from the breeding grounds near reasons for the extinction of the Great Auk, Newfoundland. suggestingmajor environmental changes as an In the Great Auk bred on a few iso- alternative, or at a least contributing factor, to lated skerries and rock islands off the south- the commonlyheld opinion that man alone was western coastand possiblyalso in a few other responsible. places.It also seemscertain that it bred at least occasionallyon the island of St. Kilda, in the DISTRIBUTION Orkneys, and possiblyalso on Shetlandand the Faroe Islands. It was certainly regularly ob- The early publishedaccounts frequently (and served around these groups of islands,and on erroneously) referred to the Great Auk as the Faroesthere are place names that indicate breedingin "the arcticseas of both continents that the siteswere usedfor driving the flight- where it is almost constantlyresident" (Bona- less Great Auks ashore. parte 1828; see also Temminck 1820, Dumont It must be taken for a fact that, at the time 1826, Thienemann 1838; all cited in Steenstrup when the Funk Island colony still flourished 1855). Steenstrup(1855) disposedof this mis- (i.e. in the 16th and 17th centuries), the Great understandingand made it quite clear that it Auk had a very limited distribution on the was a speciesof the cold-temperateparts of the eastern side of the North Atlantic and that the North Atlantic, in historical times mainly oc- numbers must have been relatively small. In curring on the western side of the Atlantic. The prehistorictimes the Europeandistribution was distribution seems to have been roughly the much wider and the subfossil records are ex- same as that of the (Sula bas- tensive (see Greenway 1958). Numerous bones sanus). In historical times, however, the west- of the Great Auk have been found in kitchen ern breedingrange of the Great Auk may have middens from northernmost (the Var- been very restricted.Many of the accountsgiv- anger District; see Olsen 1967) and southward en by voyagersand fishermen,who reported through western Europe into the Mediterra- massslaughter of breeding Great Auks in the nean (Pleistocenedeposits in ; see Violani January1984] GreatAuk Ecology 3

1974).Along the Norwegiancoast alone there "Fauna Groenlandica," Fabricius (1780) men- are about 40 sites where postglacialdeposits tioned Cottusscorpius, Cyclopterus lumpus, and (2,000-13,000 yr old) contain remains of the other of the same size as being taken. Great Auk, often in large quantities and in- The two speciesmentioned by nameundoubt- cluding youngbirds (seeGreenway 1958, Ol- edlyoccurred in the shallowwaters near where sen 1967, Hufthammer 1982). A recent mor- the auks bred, but Grieve (1885) was probably phometric study of Scandinavian bones correctin assumingthat the "other " revealeddistinct geographical variation in some were more important.The Icelandiczoologist osteologicalcharacters, and alsosome variation Saemundsson(1936: 655) stated that the Great in time (Huffhammer 1982). This indicates that Auk wasfeeding on ,other small fishes separatepopulations of the Great Auk existed or spawn,and probably also . These in Europe in prehistoric times and that some and other scattered remarks are not of much northward migrationsoccurred, as it seemsun- help in understandingthe feedingecology or likely that the speciesbred in northernmost the GreatAuk--they couldapply to any - Norway, despite its rich representation in eatingalcid. In a recentand very fascinating kitchen middens. study,however, Olson et al. (1979)attempted to assess the food of the Great Auk on Funk

FEEDING HABITS AND FOOD Island.They assumedthat the carcassesof auks slaughteredand eatenon the islandhad been The Great Auk was the largest(ca. 70 cm tall) discardedand left there to decay among the member of the contemporary alcid community, heapsof bonesthat were later found on the and the only flightlessone. It was reported to island.Thus, by analyzingsoil samplesfrom be an expert swimmer ("left a six-oaredboat siteswhere large quantities of GreatAuk bones far behind"; Grieve 1885)and diver. The wings were accumulated,they hoped to find fish re- were reduced to a size smaller than those of mainsoriginating from the digestivetracts of the allied, but much smaller, (Alca the birds. In the National Museum of Natural torda),and they were usedfor subaqueousflight. History they found a cratecontaining a field The flightlessnessof the Great Auk and of the sampleof Great Auk bones,collected by F. A. (Spheniscidae) of the southernseas Lucas on Funk Island in 1887, and from the soil is often given as an exampleof evolutionary attached to the bones a number of fish remains convergence.In this contextit may be recalled could be retrieved and identified to species. that the smaller extinct Lucas auks Most of the remains came from 140-190-ram- (Mancallacaliforniensis and M. diegense)had even longspecimens of the menhaden(Brevoortia cf. more -like wings than thoseof the Great tyrannus;Clupeidae), but there were also re- Auk and thus were even more -like mains of shad (Alosa;sp. Clupeidae), (Miller and Howard 1948). (Mallotus villosus;Osmeridae), three-spined The family Alcidae includesspecies that feed stickleback ( Gasterosteusaculeatus; Gasterostei- almostexclusively on (e.g. the murre- dae), Moronecf. saxatilis(Percichthyidae), a flat- letsSynthliboramphus), fish-eaters (Uria and Alca), fish (Pleuronectidae), and some indetermin- and intermediates(e.g. Fratercula).The plank- able teleosts. This list of prey species and ton-feedershave a relativelysmall body weight ecologicaland distributionalinformation on the and a large ratio of bill-width to gape (gape fish speciesled Olson and his colleaguesto being the distancefrom the commissuralpoint make some tentative suggestionsabout the to the tip of the culmen), whereasthe fish-feed- feeding habitsof the Great Auk: While on the ers may be small or large in size but have a breedinggrounds at Funk Islandit wasusually small bill-width/gape ratio, the Great Auk feeding in shallow waters (max. 18 m) and being at the extremeend of the scale(B•dard within 2 km of the shore. Moreover, it selected 1969). In fact, the Great Auk was so specialized relatively large prey (70-190 mm long; max. asa fish-feederthat it sacrificedits ability to fly about 300 ram) of fat specieswith a high caloric to becomeeven more adapted to pursue its prey value; the latter is typical for alcidsin general under water. (Harris and Hislop 1978). The old literature records, however, do not In the North Atlantic the large speciesof al- contain much reference to the specific food cids overlap considerably in their choice of choice(or feeding habits)of the species.In his food, but they select different size-classesof 4 $VEN-AXELBENGTSON [Auk,Vol. 101 prey in relation to their respectivebody sizes straints on its choice of nesting sites. The (Harris 1970, Swennen and Duiven 1977). It breeding skerries or islands had to provide seemsthat the GreatAuk fitted this pattern very suitable landing places,where the birds could well, taking the samespecies of fish as the oth- scrambleup a gently sloping ledge or where er fish-feedingalcids, but with a preferencefor they could get ashore by riding on the surf. large prey individuals. Once on land the Great Auk was reported to move awkwardly, but, topographypermitting, BREEDING BIOLOGY it seemedquite preparedto move away from the shoreline and nest some distance from the There are exceedingly few details available water, as on Funk Island. When leaving the concerningthe breeding habits of the Great breeding ledge it "has been known to drop Auk. Here, I have compiled what little infor- down some two fathoms off the rock into the mation there is in an attempt to reconstruct, in water" (Newton 1861). Although it has been broad and conventional terms, the breeding suggestedseveral times that the GreatAuk may strategy or ecology of the species.The discus- have nested also in some mainland sites, it sion is largely molded upon modern studiesof seems more likely that it was confined to out- other speciesof alcidsbut is limited by the few lying, more-or-lessisolated, and inaccessible "facts" about the Great Auk. Thus, I have good skerries and islands. excusesboth for speculatingand for not doing The recordsfrom Funk Island convincingly SO. testify to the gregariousnessof breeding Great Behavior.--Auksare decidedly gregariousin Auks; the colony must surely at one time have their habits, some speciesmore than others. been both large and dense (see Grieve 1885). Sightingsof Great Auk frequently referred to Compared with Funk Island, the population more than one bird, or small parties in coastal aroundIceland was probablysmall (Steenstrup waters. Their behavior was describedby New- 1855 and others), although there, also, the ton (1861) as follows: "they swam with their speciesbred in colonies:they "had their nests heads much lifted up, but their necks drawn in and eggsin common"(•lafsson and Palsson ... [they] never tried to flap along the water, 1772). At least in historical times the situation but dived as soon as alarmed ... [they] some- on Funk Island was exceptional,perhaps also times uttered a few low croaks." He also added in prehistorictimes. It hasbeen suggestedthat that "the colour of their mouths is said to have the colony size of different speciesis been yellow, as in the allied species."Several positively correlated with foraging distance other writers briefly remarked that the species (Diamond 1978; see also Lack 1968, Gaston and was often seen bobbing, or vigorously shaking Nettleship 1981). This would be consistentwith its head. Head movements, the yellow mouth, smallcolonies in the flightlessGreat Auk. Only and the large oval white patch on either side where the conditionswere exceptionallyfa- of the head between the and the eye, as vorable [i.e. island topographysuitable, protec- well as the markings on the beak, suggestthat tion from predators(including man) sufficient, the Great Auk may have indulged in socialand and available inshore food resources abun- courtshipdisplays similar to thosedescribed for dant], could a breeding place supporta large other, related speciesof auks (seeConder 1950, colony. Fisher and Lockley 1954). Time of laying.--The only reference to what Breedingsites.--As stated before, there are only might be called the date of land-comingis that a few known breeding places.Funk Island is a of Martin (1698), who visited St. Kilda in 1697 flat and low (14-m) granite rock island about and who statedthat the Great Auk "appearsthe 800 m long and 400 m wide, where today dense first of May, and goesaway about the middle coloniesof other speciesof seabirdsbreed (see of June." Now it should be remembered that Tuck 1961, who also presents habitat photo- thesedates are 11 dayslater by our presentcal- graphs). In contrast, Eldey, off southwestern ender. Moreover, it is not clear whether the Iceland, is a high (ca. 80-m) basalt rock where datesrefer to the birds comingon land or just the Great Auk bred on a broad ledge sloping to birds observed around the island. If the lat- into the sea below the northern cliffs of the ter is true, the Great Auk arrived much later island (see Fisher and Lockley 1954). The and departedearlier than did the other species flightlessnessof the speciesclearly put con- of auks breeding there. Assuming that the January1984] GreatAuk Ecology 5 statement refers to observations of birds on erby et al. 1958;there are some80 eggsknown land, it implies that the Great Auk must have from museum collections)]. Individual and sea- accomplished egg-laying, incubation, and sonal variation in egg size is a typical feature fledging (i.e. sea-goingof the young) in a pe- of Alcidae and may be an adaptive responseto riod of 6-7 weeks,starting around 12 May. This changes in environmental conditions (Birk- would mean that laying commencedslightly head and Nettleship 1982). The volume of the earlier or at about the same time as in the Ra- egg was ca. 300 cm3 (calculated from Worth zorbill, (Uria aalge),and Atlan- 1940),which is considerablymore than for the tic (Fratercula arctica). However, one eggsof the Razorbill(ca. 81-83 cm3;Lloyd 1979) should perhaps not put too much confidence and the Common Murre (ca. 96 cm3;Mahoney in the information from St. Kilda, where the and Threlfall 1981). No wonder that the Great Auk probably was not even a regular of the Great Auk were frequently collectedfor breeder, and certainly occurred in very small consumption,especially as they were probably numbers at the time of the statement. Accord- also, like eggs of murres, rich in yolk and had ing to the old annals,the Icelandicseabird fow- high calorific contents (see Tyrova 1939, Ku- lers traditionally visited the skerries and is- roda 1963). Steenstrup(1855) quoted Baron La- lands where the Great Auk bred about 24 June hotant, who spoke about large birds called to collecteggs and birds. We know that the last "moyacks"(presumably Great Auks) that bred pair breeding on Eldey had an egg in the first along the northeasterncoast of North America week of June 1844. When the crew of a vessel and laid eggs "half as big again as a swan's, visited the nearby Geirfuglasker(a skerry de- and yet they are all yolk, and sothick, that they stroyed by a series of volcanic eruptions in must be diluted with water before they can be 1830),however, they raided the Great Auk col- used in pancakes." ony for several days at the end of July and in Incubation.--Presumablyboth sexespartici- the first week of August in 1808, and the men pated in incubation, as they both had one are reported to have killed many birds and col- brood-spot each (Faber 1826), just like the lected both eggs and young (Newton 1861). A murres but unlike the Razorbill and Atlantic certain spreadin the date of laying (within and Puffin, which have two brood-spots,although between years) has commonly been found in they also lay one-egg clutches.The incubation most alcid speciesand colonies. Some of this period has been estimatedto be 39 + 5 days, variation is thought to be due to extrinsic fac- but was probably around 44 (Worth 1940). For tors (weather) and some to age differencesof comparison,the Razorbill's egg takes about 35 the birds involved. It is also a general habit of days to hatch (Lloyd 1979) and the Common auks to replace an egg that is lost (Kartaschew and Thick-billed (Uria lomvia) murres about 1960),which extendsthe laying period. In this 30-34 days(Mahoney and Threlfall 1981, Gas- context it is interesting to record that, accord- ton and Nettleship 1981). ing to Martin (1698), the Great Auk is said to Fledging.--Fisher and Lockley (1954) sug- have been the only seabirdspecies on St. Kilda gestedthat the fledging period of the Great Auk that did not lay a secondegg when the first may have been as short as 9 days; in Uria and was lost. Although the data from Iceland are Alca the chicks leave the nesting ledges at an far too scantyto permit any conclusion,I am age of about 3 weeks. The estimated fledging inclined to agree with Saemundsson (1936), time is based on Martin's statement (see above) who suggestedthat laying startedat about the that the Great Auk on St. Kilda completed the same time as in the Razorbill. In southern Ice- land-basedreproductive activities in 6-7 weeks land the Razorbill, Common Murre, and Atlan- and that incubation lasted about 40 days (see tic Puffin begin egg-laying at the end of May Worth 1940). No other information is available, (Timmermann 1938-1949). but a relatively short fledging period is not un- The egg.--The Great Auk laid a clutch of one, likely, as I will argue below. It also provides the shapeof the egg was ovate pyriform, and an explanation(not necessarilya good one) for the ground-color and markings on the shell the fact that nobody ever gave a detailed and varied in the same manner as in eggs of the convincing description of a Great Auk chick, Razorbill. The average size was about 124 x 76 and none is known to be preservedin museum mm, although size varied greatly [length 110- collections (although there are ca. 80 skins of 140 mm, breadth 71-84 mm (Bent 1946, With- full-grown birds)--the chicks spent but a few 6 $VEN-AXELBENGTSON [Auk,Vol. 101

dayson land, and, while at sea,they may have some other species are independent when been difficult to catch. fledged) and the family could have followed Discussion.--Aukecology is, for obvious rea- the movementsof the prey species,whichmay sons, mostly concerned with events that take often have been migratory pelagicfishes. place at the breeding sites;the life at seais far The scanty recordsavailable are reconcilable more difficult to study. Often the breeding with the fledging strategy outlined above. It strategiesof alcid speciesare describedand appearsthat the Great Auk may not have come comparedin terms of an interplay between ashoreuntil shortly before egg-laying started feedinghabits [food choice, feeding range, food (Martin 1698),which is in sharp contrastto the resources,parents' capacity to carry food to the most closely related species.The combined in- chick(s),etc.], fledging period (growth-rate pat- cubation and fledging period may have been ),and nest-siteselection (protection against somewherebetween 43 and 53 days (p. 5), or , adverse weather, etc.). When the about the same as for the much smaller Razor- Great Auk still existedsix other speciesof the bill (ca. 55 days) and murres (ca. 50-54 days); family Alcidae also occurred in the North At- for the smallestspecies, the Dovekie, it is 52 lantic [viz. , Common Murre, days(Evans 1981). Among species of the family Thick-billed Murre, Black ( Alcidae, the fledging period varies consider- grylle), Dovekie (Alle alle), and Razorbill], al- ably, not only betweenspecies, but alsoto some though their breeding rangeswere only par- extentbetween individuals of the samespecies. tially overlapping.In severalrespects the Great Chicksof Synthliboramphusare truly precocial Auk was the odd member of the assemblage, and leave their nestswithin 2 daysof hatching and not only becauseit eventually went ex- (Sealy 1973), whereas for Alca and Uria the tinct. It was the most highly specializedof all fledgingtime is about20 days(Birkhead 1977a), for a , being the largest(ca. 5,000 g; for the Dovekie 27 days (Norderhaug 1970),for estimatedby B•dard 1969)and the only flight- the BlackGuillemot 36 days(Kartaschew 1960), lessone. This probablymade it a very efficient and for the Atlantic Puffin about 36-40 days fish-feeder (like the penguins), but also im- (Ashcroft 1979). posedcertain constraintson breeding perfor- It has been suggestedthat the length of the mance. For instance, its foraging radius was fledging period is positivelycorrelated with the limited aslong asthe centralplace was the egg degree of protection of the nest site, species or the chickon land, and suitablenesting sites breeding on exposedledges, such as murres, that provided both plenty of food at the right having a shorter fledging time than those nest- time and safety from predatorsmay not have ing in crevicesand , such as , been that common.Because of its body size,the Black , and Dovekies (Fisher and Great Auk may have been able to bring quite Lockley 1954: 252, Cody 1973; but see Lack large meals to the chick each time one of the 1968). It remains to be demonstrated, however, parents take the trouble to climb ashore.A full- that the chicks are more vulnerable to such fac- grown bird, however, usually selectedlarge torsas predation and hard weatheron land than prey (p. 3), whereasthe small chick probably at sea.More recently,the length of the fledging required smaller-sizedfood items, which may period has been discussedin terms of the par- have been more costly to collect. Moreover, a ents ability to bring provisionsand the type full-grown GreatAuk may have requiredabout and abundanceof available food (Sealy 1973, 1,000g of fish per day for its own maintenance; and a number of later authors).Providing food an adult murrethat weightsabout • the weight both for themselvesand for young in the nest of a Great Auk needsabout 200 g (Sanford and may place a considerablestrain on the parents; Harris 1967, Marsault 1975). All this taken to- for instance,the energy expendituresof House gether suggeststhat the Great Auk ought to Martins (Delichonurbica) rearing young are 3.59 have minimized the amountof time spent on times the basal metabolic rate, or about twice incubationand fledging of the chick. The total as much as for other stages(Bryant and Wes- energetic costsof producing the offspring can- terterp 1980). So the parents should (it would not be negotiated,only the time pattern of the seem)carefully "consider"the implicationsof expenditures.By getting the chick sea-borne central-placeforaging theory (Andersson1978, the parents could have fed it more easily (al- Orians and Perason 1979, Schoener 1979). For though they may not have done so; chicks of alcids that feed on unpredictable food re- January1984] GreatAuk Ecology 7

sourcesor that must fly long distancesto collect although we should not take Lahotant's state- food for the chick, an early departure to sea ment about the yolk in Great Auk eggs(p. 5) seemsadvantageous (Sealy 1973). The problem too seriously. The Great Auk did lay a large facing the flightlessGreat Auk was that it could egg, however, ensuring a large total amount of not cover any large distancesto collect food calories.Chicks of alcids depend on the yolk and at the same time maintain a sufficiently sacfor a few daysafter hatching,and chicksof high feeding rate of the chick on land. More- Uria do not achieve homeothermy until 9-10 over, it was a large-sized speciesand required daysof age (Johnsonand West 1975).Once their a lot of food. An early fledging, so that the own metabolismis in full working order there chick could follow the parents to the food, is alsoa metabolic increase.If this can be extrap- would thus be a good strategy to adopt, espe- olated to apply also to the Great Auk, it adds cially if the chick alsoquickly becameindepen- another arguement in favor of a 9-10-day dent and aquired its own food. The suggested fledging period; the chick left the nestingledge fledging period of 9-10 days seemsshort, but very soon after it achieved adequate thermo- may neverthelesshave been true. regulation, but before its energy demands in- To producean "advanced"chick, a relatively creasedmarkedly. large and/or nutritionally rich egg is a prereq- Why did the Great Auk not provide even uisite. Among alcids, the precocialspecies lay more for the newly hatched chick by produc- the relatively largesteggs, weighing about20% ing an even larger egg? The simplest answer of adult body weight in the murrelets (Sealy would be that it could not, that it would im- 1975), 12-14% in Uria and Alca (Birkhead 1977a), pose too much strain on the female. The size and 13 and 19% in Atlantic Puffin and Dovekie, of an egg is determined by both intrinsic and respectively(Kartaschew 1960). In the Great environmental factors--the quality of the fe- Auk the egg may have weighed about 325 g, male and the amount of food and time avail- or about 6-7% of adult weight. The newly able. In alcids (as in many other, possiblyall, hatched chick may have weighed around 200 birds) egg size declineswith season,which can g, comparedwith 62 g in the Razorbill (Lloyd be interpreted as an adaptive trade-off between 1979)and 82 g in the Thick-billed Murre (Gas- egg size and laying date, as discussedfor the ton and Nettleship 1981). Chicks of Uria and Thick-billed Murre (Birkhead and Nettleship Alca approximately double their weights dur- 1982). If the female had been capable of pro- ing the first 8-10 daysposthatching. Assuming ducing a larger egg, she would have had to that this held true also for the Great Auk, its build up a larger energy reserve,which prob- chick weighed 8-10% of adult weight when it ably would have delayed the laying date and supposedlyfledged. This would placethe Great certainly would have lengthened the incuba- Auk very closeto the murrelets (Synthliboram- tion period, but would not necessarilyhave phus),which have precocialchicks, as the chicks shortened the fledging period. The date of of the semi-precocialspecies (e.g. auklets, puf- hatchingwas probablycritical to breeding suc- fins, and small guillemots) fledge at 65-90% of cess;starvation among alcid chicksis frequent- adult weight, and the intermediatespecies (Uria ly invoked in explainingbreeding failure. From and Alca)weigh 20-25% of adult weight (Sealy the meagre recordsit seemsthat the Great Auk 1973). It should be noted, however, that there commencedegg laying at about the sametime is usually a great deal of variation in fledging as, for instance, the Razorbill and the murres. weight with date of hatching,between years, Becauseof its slightly longer incubation peri- and between colonies (see Gaston and Nettle- od, it hatched a week or 10 days later than the ship 1981). other speciesmentioned, but, assumingthat it There is a general, positive relationship be- adopted the fast fledging strategy suggested, tween the yolk content of an egg and devel- the GreatAuk chickmay have been feeding by opmental maturity at hatching (Heinroth 1922, itself a few days before the bulk of chicks of Nice 1962), and an increase in proportion of other speciesleft the nesting ledges. That an yolk and yolk lipid level, solids, and caloric early laying and fledging may have been cru- content and a decrease in water content are cial is also indicatedby the statement(Martin claimed to be correlatedwith degree of precoc- 1698) that the Great Auk did not replace the ity (Ricklefs1977, Carey et al. 1980;but seeWil- egg if it was lost, although other alcids do re- liams et al. 1982). This is true also for alcids, place lost eggs. Being a large-sized and pre- 8 SVEN-AXELBENGTSON [Auk, Vol. 101 sumably long-lived bird, the Great Auk could Sometimes,when the weather so permitted, the probablyafford not to investtoo muchin a year crews would "draue a great number of the that did not turn out as it should. Although fowles into their boatsupon their sayles,"or nothing is known about its longevity and rate "driue them on a plank." Grieve (1885) quotes of reproduction, it is not unreasonableto as- one early visitor, who in about half an hour sume that the Great Auk may have taken 4-7 loaded his two vessels with 4 or 5 tons of dead yr to reachmaturity and that survival rate was "Penguins," not counting those that the crews high. For instance,the Razorbill doesnot breed had consumed fresh; i.e. about 1,000 birds. No for the first time until 4-5 yr old, and, although matter how large the population was, the num- only 0.13of the young reachbreeding age, adult bers taken must have implied that the popu- annual survival is 0.90 or more (Lloyd and Per- lation was being overexploited. The same was rins 1977). Very similar results have been ob- undoubtedly true, although on a smaller scale, tained for the Common Murre and Atlantic Puf- at the few Europeanbreeding sitesknown from fin (Birkhead and Hudson 1977, Harris 1983). historicalrecords. On the breeding islandsoff Individual GreatAuks may often have reached Cape Reykjanes,southwestern Iceland, the to- an age of 20-25 yr and possiblydid not breed tal population of Great Auk possiblyonly num- every year. In contrast to the other North At- bered a few hundred birds (or less) at the end lantic alcids, the species did not breed in the of the 18th century, but between 1813 and 1844 northernmostregions, which may indicate that at least about 75 birds are known to have been it was more sensitive to late and cold seasons killed. Despite the comparatively moderate than the others. Like the closelyrelated species numbers killed, the specieswas probably al- (Razorbill and murres; Southern et al. 1965, ready beyond the point of rescue,although not Birkhead 1977b, Lloyd 1979), the Great Auk until 1835 do we meet with an author who ex- probably exhibited a high degree of nest-site plicitly expressedconcern for the species'sur- and mate fidelity. vival (Nilsson 1835). For conveniencewe may separateprehistoric DECLINE AND DISAPPEARANCE and historictimes when consideringman's role in the decline of the Great Auk. Setting the When the Great Auk was finally exterminat- time-boundary at about year 1500 (though there ed off Iceland during the first half of the 19th are some older historical records), we have al- century (in North America probably before ready seen that the specieswas rare in Europe 1800),its fate had long been sealed.Most of the and had a very limited breeding distribution literature consists of records of subfossil bones on the western side of the Atlantic. This in it- found in kitchen middens, "last observations," self made the Great Auk highly vulnerable to and massslaughters and ruthless collecting of extinction,and the recordsunequivocally point the specieson its breeding grounds.It is there- in the direction of over-exploitation by man. fore not surprising that almost every writer In prehistorictimes the speciesin all probabil- maintains that the Great Auk was exterminated ity had a much wider distribution on both sides by man. When the Europeans(re-)discovered of the North Atlantic (pp. 2-3), and the fossil Newfoundland in 1497, a period of intensive records testify that it was hunted by Indians exploitation of the rich fishing grounds there and Eskimos in North America (Salomonsen started, and each year an armada of 300-400 1945) and by Scandinavians,Icelanders, Far- French, Spanish, Portuguese,and British ves- oese,and othersin Europe.The questionis, did selsvisited the area. It becamecustomary to call the prehistoric hunters also over-exploit the in at rich seabird coloniesto reinforce the sup- Great Auk and thereby cause(or contribute to) plies with fresh meat. On what must have been its decline, which must have taken place prior Funk Island, the fishing crews collectedGreat to 15007 For them the situation was different Auksby the thousands,and the birdswere salt- from that of the voyagers raiding the colony ed and barreled or boiled and eaten on the spot, on Funk Island, becausethe hunters had to rely using the fat from some of the birds for fuel on the Great Auk (and other ) for sub- (see accountsin Steenstrup 1855, Grieve 1885). sistence,and prudence in exploitation seemed On Funk Island there are still remains of huts a necessity(although admittedly some sailors and pounds made of stones, into which the may have savedtheir lives by collectingGreat flightlessbirds were driven to be slaughtered. Auks). For instance,in the Faroesthe collecting January1984] GreatAuk Ecology 9 of seabirds has been of economic importance Great Auks breeding on Funk Island have even in the present century, but there are no changed their distribution since then. Tuck indicationsthat this extensivefowling by mod- (1961: 24) suggeststhat the Great Auk was pos- ern huntershas had any negativeeffects on the sibly more vulnerable to meteorologicaldisas- number of birds or has been responsiblefor ters,less tolerant of low temperatures,and less any marked population fluctuations(N•5rre- catholic in its choice of food than murres. vang 1977,pers. comm.).The Faroesefowlers What evidence is there for major environ- knew their birds from experienceand "moni- mental changesthat couldconceivably have af- tored" their numbers, imposed regulations fected the abundance of the Great Auk? Cli- when needed,and only rarely and accidentally matic fluctuationsin the North Atlantic region did they taketoo many birdson a certainledge manifest themselves in the amount of sea ice or part of a colony. One may, perhaps,argue drifting southwardfrom the polar seas,and cold that the suggestedprudence of the prehistoric periods seem to occurabout every 2,500 yr. The huntersonly appliedto the mostabundant, and latestcold period, known asthe "," consequentlymost important,. prey species. The started in the 13th century or slightly earlier, Great Auk was probably nearly always out- and lasted at least until the beginning of the numberedby otherspecies of alcids,and being present century. It was characterizedby cold so large and rare, it may in fact have suffered summers, harvest failures, famines, and local a sortof "negative"apostatic selection; i.e. being human or at least changes in the taken in preferenceto the smallerspecies. The distribution of settlements (see John 1977). Great Auk did not suddenly disappear when Scandinavian colonized the Faroes, man entered the arena and began to hunt for Iceland, and parts of Greenland between 800 it. Rather,for thousandsof yearsman and bird and 1000 and established settlements also on lived together,and the total numberof prehis- the coasts of and Newfoundland. Al- torichunters was probably not fewerthan those ready at the beginning of the 1400'sthe west- people killing the bird in historic times. For ernmost settlementswere gone, presumably as instance, in Norway, where there are numer- a result of a climatic deterioration. In northern ous archeologicalfinds of Great Auk remains Europe the climatic conditionsalso causedde- in kitchen middens, the earliest depositsdate clines in human populations. 12,000-13,000yr B.P.and the youngestare about By far the best historicalrecords of weather 1,500-1,800yr old (Olsen 1967, Hufthammer conditions in the North Atlantic come from the 1982).It is noteworthy,however, that the rich Old Icelandic sagas, annals, and chronicles, depositsfrom Medieval time in Norway (ca. going back for about 1,000 yr. The amount of 1050-1550) do not contain any bones of the sea ice around the coasts of Iceland seems to Great Auk. In my opinion, the decline of the have increasedin the 12th century as the cli- Great Auk commenced long before man is mate deteriorated.Apart from a period of im- known to have caused havoc in breeding col- proved conditions in the first half of the 15th onies in the mid-16th century and onwards. century, a major improvement did not occur Remarkablyfew alternativeexplanations for until the late 1800's(Bergthorsson 1969). From the decline and extinction of the Great Auk 1200 to 1600 there are fairly frequent reports have been advanced. Several writers have of severe sea-ice conditions, and from then on pointed out that the speciesfrequently nested the records are more detailed and indicate even at sites that were vulnerable to geological de- worse conditions (several papers in Einarsson struction(e.g. Steenstrup1885). This is certain- 1969; see also Eythorsson and Sigtryggsson ly what happenedto the rock Geirfuglaskerin 1971). In some years the ice also reached the Iceland (p. 5), but it only made the breeding southernmostparts of Iceland, and the Great birds move over to the adjacentEldey, and the Auks breeding islandswere undoubtedly com- consequenceswere, of course,negligible com- pletely surrounded and blocked by pack ice. pared with thoseof major ecologicalchanges. The old records contain many referencesto For instance,even a rather small change in sea failures of the grassharvest, and also mention temperaturemay have profoundeffects on the that somespecies of birds were unable to "bring abundanceand distribution of prey species.As out their broods." There were also more fre- a casein point, Olson et al. (1979) note that quent visits by polar (ThaIassarctosmari- some of the fish speciespresumably eaten by timus),and the harp seal (Pagophilusgroenlan- 10 SVEN-AXELBENGTSON [Auk,Vol. 101 dicus), which does not occur in these waters spaceof the herring (Clupeaharrengus) stock is today, was abundant in someyears, to the ben- a good example. Alcids may respondto dete- efit of the hunting islanders. riorating conditions (cooler climate and less Thus, there is good evidence that a climati- food) by not breeding or by laying eggs and cally severeperiod precededand coincidedwith hatching chicks that then often die from star- the period when man was dogging the Great vation. Recently, for example, changesin the Auk. In the absence of more detailed infor- food situation of the large puffin colonies on mation about the rate of decline of the bird Lofoten, northern Norway (believed to be at populations, hunting pressure,and the envi- least partly due to overfishing by man) have ronmental changes,we cannot separatethe ef- causedmass starvation among newly hatched fect of hunting and that of climate. There is chicksfor a long run of years(Mills 1981, 1983). good evidencethat climatic changesdirectly or Many alcidsare, however, long-lived birds, and indirectly affect alcid populations (e.g. Tuck a given colony can probablytake a number of 1961). One such example is Tuck's account of nonbreeding years without experiencing any the history of Common Murres and Northern marked population decline. Besides,common Gannets on Funk Island. The former species and widely distributed speciesare probably was apparently abundant during Cartier's visit successfulin some parts of their breeding range to the island in 1534 and also in 1874, although and, therefore,are more likely to recoverfrom insignificantnumbers were reporteda few years hard times. The Great Auk was possiblynever later (1887). Since about 1885, and particularly very numerous and was restricted to a relative- since 1920, the rise in temperature has caused ly narrow climatic zone, not breeding in the the amount of sea ice to decrease and Arctic regions. Moreover, the colonies were the cold surfacelayer of the sea to diminish. possiblyoften rather small, and, being a large From 1936 to 1959 the number of breeding but flightlessbird, the Great Auk probably re- Common Murres on Funk Island increased from quired a combination of a safe breeding place about 10,000 to 500,000, and Tuck (1961) ar- surrounded by rich supplies of food to repro- gued that this dramatic increaseas well as pre- duce successfully.These traits in the life his- vious declines were responses to climatic tory of the Great Auk probably made it more changesand ecologicalphenomena associated vulnerable to climatic changes (expressing with them. Similarly, the abundanceof North- themselvesin various ecological phenomena) ern Gannetshas changedon Funk Island from than are other speciesof North Atlantic Alci- large numbers in 1534, none in the 19th cen- dae. Of course, it also became more vulnerable tury, 7 pairs in 1936,nearly 2,800 pairs in 1959, to the destructive activities of man. to 4,051 pairs in 1972,according to recent counts I wish to end this paper by re-emphasizing (Tuck 1961, Nelson 1978). The changesof the that my discussionof the ecologyof the Great Northern Gannet, and of its main prey, the Auk is based on very few indisputable facts. mackerel(Scomber scombrus), are alsoparalleled Also, the final section is not intended to acquit by changesof the marine environment. Many man of his guilt in the extermination of the more examples from both sides of the North Great Auk, but to point to other possible con- Atlantic could be cited to show that alcids and tributory reasonsfor the declineand extinction other speciesof seabirdshave responded to cli- of the species. matic ameliorationsin recent times. The point I wish to make is that ups and downs in late- ACKNOWI,EDGMENT$ Pleistoceneclimate very probably had effects I am grateful to Mrs. Ulla Holmberg, who assisted on the distribution and abundance of prehis- in the literature search, to Dr. Pehr H. Enckell for toric populationsof alcids;possibly the effects encouragingdiscussions, and to Dr. Anne Karin Huf- were more pronouncedon the large and spe- thammer, who allowed me to cite her unpublished cialized Great Auk than on the other species. thesis. I also thank Dr. John A. Wiens for the invi- Alcid populationnumbers are ultimately de- tation to write this paper and for patience and lin- termined and regulated by the abundance of guistic scrutiny. available food (Ashmole 1963, Rowan 1965), and LITERATURE CITED even very small changes in sea-water temper- ature may have large effectson the abundance ANDERSSON,M. 1978. Optimal foraging area: size and distributionof prey organisms.In the east- and allocation of search effort. Theor. Pop. Biol. ern North Atlantic, the fluctuations in time and 13: 397-409. January1984] GreatAuk Ecology 11

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