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WESTERN

Volume 15, Number 4, 1984

BREEDING PHENOLOGY AND MID-SEASONAL SOCIAL BEHAVIOR OF THE SOOTY ON TEUR! ISLAND, JAPAN

ASA C. THORESEN• Biology DepartmenL Andrews University,Berrien Springs, Michigan 49104

The breeding biology of the (Alcidae) is representedin literaturefor two of the three species:Cepphus grylle, the and Cepphus columba, the (Asbirk 1978, 1979a and b; Cairns 1978, 1979, 1980, 1981: Drent 1965: Hyde 1936, 1937; Preston 1968: Storer 1952: Thoresen and Booth 1958; Winn 1950). Notations within larger compilations (Dement'ev and Gladkov 1951, Kozlova 1957) and a short paper by Nazarov and Labzyuk (1972) have been the only reportspublished on the habitsof Cepphuscarbo, the Sooty (or Spectacled) Guillemot.Austin and Kuroda (1953) recordeda populationof at least7000 Sooty Guillemotson Teuri Island, Japan, in 1949, which was at that time the largestknown aggregationof the genusanywhere in the world. Unfortunate- ly, this figure is difficult to substantiateand the present number on Teuri Island does not exceed 400 birds, includingnon-breeders (Environmental Agency 1973). Colonies twice the size inhabit Soviet islandsto the north (Nazarovand Labzyuk1972). I campedon Teuri Islandin June and July 1981, to observethe breedinghabits of this little studiedspecies. All three speciesof Cepphusnest as individualpairs, in smallgroups, or in largergroups -- up to 10,000 pairsfor the BlackGuillemot (Nettleship 1974) -- accordingto the availabilityof nestingcavities and abundanceof food sup- ply. The Sooty Guillemotranges from the coastsof northernJapan, Korea, and southern Kuriles to the shores of the Okhotsk Sea (Dement'ev and Gladkov 1951). The differsfrom the other two speciesin beingslightly larger,lacking white wing patches, and possessingwhite eyelids which merge with white facialplumage. As in the other two species,the Sooty has con- spicuouslyred feet and legs.The interiorlining of the mouth is fleshpink as opposed to the brightcoral red of the Black and Pigeon . WesTern Birds 15:145-160. 1984 145 SOOTY GUILLEMOT

STUDY AREA AND METHODS

Teuri Island (lat. 44ø4'N, long. 141ø3'E), is one of two islandslocated ap- proximately 38 km off the northwestcoast of Haboro, Hokkaido, Japan. Teuri is famous in Japan as a National Monument for seabirdsand is a well- known tourist attraction (Environmental Agency 1973). Teuri Island is approximately5.5 km2 and has almost 12 km of coastline, one third of which is suitablefor breedingseabirds. The islandrises gently at the north end from east to west and more abruptly at the south end to high points of approximately 100 m. The rock is composed of volcanicbreccia overlain with ash conglomerates.Several rocky stacksalong the western shoreline also provide nestingplaces for birds. A village of just over 1000 persons is located at the sheltered northeasternend of the island. The sea was remarkablycalm during June and July althougha few wet, foggy and windy days impeded observations.Air temperaturesvaried be- tween 16 and 20 ø C, and the sea temperaturesat shore were just a degree or two belowair temperature.Tidal effectwas practicallynil, with a differenceof lessthan 1 m between high and low throughoutJune and July. Teuri Island is the site of the largestknown colony of RhinocerosAuklets (Cerorhinca monocerata) where a minimum of 500,000 and a maximum estimation of 785,000 individuals breed (Environmental Agency 1973). Other breedingspecies include Black-tailedGull, Laru$ cra$$iro$tri$,40,000; Slaty-backedGull. Larus$chi$tisagu$. 400: , aalge. 700 to 800: Sooty Guillemot, Cepphu$ carbo, 380 to 400: and a few scattered Ancient Murrelets, $ynthliborarnphu$ antiquu$. (All figures represent individuals.) I camped on Teuri from 3 June to 31 July 1981, observingfor more than 700 hours. From within 25 to 50 m of the campsite 20 or more Sooty Guillemotscould be observed. An additional group of birds could be seen

Figure1. Part of the studyarea on TeuriIsland, Japan.

146 SOOTY GUILLEMOT easilywith binocularsto the south.To the north, beyondrock piles.the remaining300 plus birdswere countedeach day shortlyafter dawn and at intervalsthroughout the day. Attendance counts were made by counting everyhour all birdswithin view of the campsitearea on the seaand on land near nestingsites. Locations of nest cavitieswere determinedby observing the movementsof the birdsto and from the cliffs.Sightings of birdscarrying were used to determine locations of nest sites in which chicks were present. A rock blind was constructedfrom which the entranceto eight nestsknown to containchicks could be seen. Among the boulderpiles at the baseof the cliff20 nestswere locatedbut only 7 of thesewere shallowenough to permit access to their contents. Binoculars,notebook. tape recorder.a 16 mm motion picturecamera and a 35 mm motor-driven camera were used for recordingbehavior. The early matingbehavior was entirely missed. nevertheless social activities continued throughoutJune and July. Figure 1 picturesthe campsiteand part of the observationarea on Teuri. Figure 2 showsfour adult birds.

RESULTS AND DISCUSSION Breeding Chronology and Development of Young Storer (1952)indicated that the prenuptial (prealternate)molt of the Sooty Guillemot appeared to occur in January and February in northern Japan. This observationfits in well with the early onset of breeding activitieswhich take place on Teuri Island. Eggs were already hatching on 2 June 1981. On 5 June, five of seven accessiblenests contained eggs: three containedtwo eggsand two only one. Matutoshi Aotsuka. warden of birds on Teuri Island. informed me that the

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...

Figure 2. Adult Sooty Guillemots perched near a nestingarea One bird utters the alarm Scream from a resting position

147 SOOTY GUILLEMOT eggsusually hatched at aboutthe sametime everyyear and that, in 17 years of banding birds on Teuri, he had never found more than one Sooty Guillemot chickbeing fledged from a nest. Nazarov and Labzyuk (1972) also could find only one chick in each nest they examined. My observations showed that although two chicksmay hatch, only one fledges. In one nest the secondchick to hatch was found dead on the secondday with its head severelypecked. On 4 July 1981 the first fledgling was seen on the bay, where it was observeddaily until 20 July. Allowing 40 plus days for the nestlingstage (basedon recordsfrom three nests)and assumingthat the incubationperiod averaged 30 days, the first eggsof the Sooty Guillemot on Teuri probably were laid about 26 April and hatched 26 May. To the north Nazarov and Labzyuk (1972) found the earliesteggs on 8 May with the greatestnumber being laid after 20 May. Of a maximum population of about 400 individuals, no more than 200 were breedersin 1981. In otherwords, there may have been a maximumof 100 nestswith a lessernumber of pairs rearingyoung. Nestswere located under rock piles, in crevices,and under rocks higher on the slopes.Sixty percent of the nest sites, as determinedby observingbirds flying to them, were more than 20 m above sea level (see Figure 3). Nest siteswere often defendedlate in the seasonby adultswithout eggs or youngbeing raised in them. Preston (1968) noted this behavior also in the Black Guillemot on Kent Island in all five years of his study. Throughout June and July, I observeddaily 5 to 10 non-breederswhich were stillin mottled-greybelly plumage. These immature birds displayed with the other membersof the colony.Kozlova (1957) and Nazarovand Labzyuk (1972) have also noted that young birdsfrequently retain white featherslate into June. The eggs of the Sooty Guillemotsresemble in appearancethose of the other two species.The two eggsof a singleclutch are not alwaysmarked alike, a feature also noted in the Pigeon Guillemot (Thoresenand Booth 1958). However, Asbirk (1979b) commented that the two eggs from the sameclutch of DanishBlack Guillemots always have the sameground color and the same pattern of spots.Ten eggson Teuri averaged60.37 x 41.70 mm with a range of 57.60 - 63.80 x 40.3 - 43.8 mm. These were smaller than 14 eggsmeasured by Nazarovand Labzyuk(1972) who on more north- erly islandsfound a rangeof 61.1 - 66.8 x 41.1 - 45.2 mm. Nine eggsat late stagesof incubationhad an averageweight of 55.57 g with a range of 50.0 - 60.1 g. Chickswere fed at varyingperiods during the day. Early morningand late evening feedings were more frequent than midday feedingsin 20 nests observed.Three to eight feedingsper day, with an averageof five, were observedon four differentdays, from dawn until sunset.Small chickswere usuallyfed fish 4-6 cm long. Occasionallya fish, too large for a chickto swallow,was eitherleft at the nestsite or carriedaway againby the parent. The mostcommon fish seenbeing brought to the nestwere sandlance (Am- rnoclytessp.), rock blennies (Pholissp.) and small .Three 20 cm sandlance weighingbetween 28 and 29 were droppedat one nest. (A single 4.0 cm sand lance weighedonly 2.0 g). As is well known, Cepphusfeed

148 SOOTY GUILLEMOT upon practicallyany small fish they are capableof catching.For example, Follett and Ainley (1976), in a study of the Pigeon Guillemot in central found representativesof 10 families of fish including 19 genera and 24 speciesto form the prey of that species.The Sooty Guillemotis pro- bably just as adaptablein its diet. The chicksof Sooty Guillemots,upon hatching,look just like the young chicksof the other two species.They have a full coveringof sooty-black down. The legs and feet are pink, turningblack in a day or two. The bill is also black with a prominentwhite egg-tooth on the top mandible,while at the tip of the lower mandible a smaller egg tooth is also present. These featuresmatch those of the other speciesof Cepphus(Sealy 1970). Both egg teeth graduallywear off, but in the three chicksobserved to fiedging,a rem- nant of the upper one remained up to the 40th day. A singlechick hatched with a body weightof lessthan 40.0 g, reacheda peak of 605 g by Day 38, and declinedto 545 g the day before fledging. Body feathersand remigesbegan to show on Days 12 and 15 after which the belly feathersdeveloped a mixtureof white and sootyblack. The head, neck and dorsumincluding the wingsand tail were a uniform sooty-blackby fledgingtime. The eyelidswere white and an area aroundthe eyes,destined in maturityto becomewhite, remainednaked until closeto fledgingwhen it filled in thinly with fine grey feathers.The feet and legsupon fledgingwere black or dark grey. Figure 4 picturesa juvenile in the nest cavity the day before it fledged.

lOOm

50m --

25m 60 per cent above 20 m

Figure3. Profileof TeuriIsland cliffs showing distribution of Sooty Guillemotnests above sea level.

149 SOOTY GUILLEMOT

One fledglingwas observedfor 16 days from 4 July through 19 July, feedingalone very closeto shore.It wasa remarkablytame bird often allow- ing my approachto withina few meters.When firstsighted it wasmidway out in the bay amongadult-plumaged birds which kept threateningit and driving it awayfrom the group.One adultdived repeatedly after the youngone until both were out of sightbehind rocks at the bay entrance.At that time the feet and legsof the fledglingwere noticeablyas darkin coloras a nestling's.After 12 days its plumage had changedfrom slaty to brown. Dement'evand Gladkov (1951) also describedthe brownishcolor of the juvenal plumage in Cepphus carbo. Nazarov and Labzyuk (1972) noted that in August the juvenilesbecome brown. Also by 12 days the feet and legshad becomea brownish-redand by 19 July they were almostas brightred as an adult's. The bird neverattempted to fly in the 16 daysit wasobserved. The fledgling, unlikethe maturebirds, always swam with its neckwithdrawn. It alsoboldly defended itself. On one occasionI saw the fledglingattack a bathingBlack- tailed so vigorouslythat it ploughedup onto the gull'sback, causing the gullto fly away.Fledging of threebirds in observednests occurred on 20 July (Day 45), 21 July (Day 44) and 29 July (Day 40). As evidencedby missingwing feathers in fiveadults, and the greyingof the back of the head and neck plumagein four birds,the annual prebasicmolt beganat the beginningof July. All four birdsseen to be in molt were still feeding young. Colony Attendance Towardthe end of the firstweek of July a noticeableswitch in the pattern of attendanceoccurred. Figure 5 showsa gradualshift in attendanceto later in the day. This unexplainedchange of patternin colonyattendance by the

Figure4. A 44-day-old Sooty Guillemotnestling in its nestcavity the day beforeit fledged.

150 4-20 JUN 14 10 7 8 8 8 9 8

2O

• 4 21 JUN-11 JUL • / 14 7 15 8 7 6 7 7 < 30

• 2 o

o 1

12 --20 JUL 40' 7 6 5 9 11 10 13 14

10-

z 21-30 JUL 4 8 9 ]0 9 8 9 13 20 3

6 8 10 12 ]4 16 ]8 20 HOUR OF DAY

Figure5. Colony attendanceof Sooty Guillemotsat intervalsduring June, July and August 1981. Figuresat the top of each graph representnumber of countsaveraged for each 2-hour period. Colony attendanceincludes birds on land and on the water close to shore.

151 SOOTY GUILLEMOT

Sooty Guillemotswas unlikethe uniformattendance patterns throughout the breedingseason demonstrated by the Pigeon Guillemot (Drent 1965), and the data presented by Asbirk (1976b) and Cairns (1979) for the Black Guillemot. In June, birds arrived in large numbersat dawn and were active on the sea and at the breedingsites until 1500 to 1600 after whichtime only a few scatteredindividuals were observablewithin 0.5 km of shore. By 20 June, a detectablelowering of numbersoccurred between 0900 and 1100 eachday. By noon a largepercentage of the populationreturned to the rocks and cavityentrances to defend eitherempty or occupiednest cavities. By 12 July, only the few birdsfeeding young were ever closeto land before 1000. Most other birdsreturned at about 1300 and stayeduntil 1900. Sunsetat this period was between 1915 and 1930. A few were still at their perchesnear their nests until 2000. Slight variationsoccurred with the weather but in general the weather appeared to have little effect on activity. The low numbersof birdscarrying fish during the latter half of July indicatedthat the change in colony attendancehad nothing to do with growingdemands for food by young. Behavior The habitsof the Sooty Guillemotclosely resemble those of the other two speciesof the genus. Sooty Guillemotson Teuri were very sensitiveand suspiciousbirds. Kozlova (1957) also noted their shyness. I partially attributedtheir caution to the alarm calls and frequent panic flightsof the Black-tailedGulls. Incubatingbirds would flushat the slightestsound such as a fallingrock within 10 m. However, in an area immediatelybelow a tourist observationplatform near the top of the cliffson Teuri, one pair showed little concern for the presenceof man. There they seemed to be conditionedto people. Sooty Guillemotswhen not disturbedalmost alwaysmade a direct flight into the nest when carrying fish to their young. If a fish-carryingbird did hesitateit was chasedby a gull (sixout of sevenobservations) attempting to snatch the fish.

Discussion of Behaviors The sounds produced by the Sooty Guillemot were found to be less intense than those of the Pigeon Guillemot. For example, the strong "seeeooo" of the alarm or warning scream of the Pigeon Guillemot is reduced to a thinner sounding"seeee" in the Sooty Guillemot (Figure 6c). The "tsit" or "chip" sound (Figure 6d) is similar in all three species of Cepp!•usand is given at varying intervals,even in flight. The contextsand interpretationsof behaviorsobserved are summarizedin Table 1. The trilled call (Figure 6a and b) lacked the "seeeooo"addition in the middle of the call usuallyheard in Pigeon Guillemotsand in thisrespect more closelyresembled the descriptionsgiven for the Black Guillemot (Preston 1968, Storer 1952, Thoresen and Booth 1958, Drent 1965). Asbirk (1979a) refers to this call in the Black Guillemot as the "Nest song," which I believe rightlyidentifies it with nest territoryownership. Squat-peepingor Hunch-whistleis one of the most common social displaysseen in all three speciesof guillemots(Figure 7a). Some observers

152 SOOTY GUILLEMOT have interpreted it as an aggressivedisplay (Asbirk 1979b, Drent 1965, Preston 1968). However, my observationson the Sooty Guillemot did not always reveal an aggressive action. Squat-peeping was sometimes demonstratedby a singlebird in a group or at the nest site when an intruder landed nearby. In all of my hundredsof observationsof Squat-peeping, Strut-circling by a second bird accompanied it. Strut-circling was characterizedby frequent Head-dipping while swimmingaround the squat- peeper. Squat-peepingmay be a signof being mated both in the Sooty and the PigeonGuillemot. Numerous observations on both speciesindicated that when a mated bird, sittingnear its nest entranceor on the water below the nest site, was approachedby an intruder the former began to Squat-peep. This attracted the mate if it was within calling distance. When the mate arrived it respondedby circlingthe squat-peepingbird. This demonstration usually encouraged the intruder to leave without attack. Otherwise the arrivingmated bird displacedthe intruderby Strutting,Hunthing or attack. Twitter-waggle(see Figure 7b) is an aggressivedisplay common to all three speciesof the genusalthough Drent (1965) interpretedTwitter-waggle in the PigeonGuillemot to be an appeasementaction. In the Sooty Guillemot, the action was strongly aggressiveand frequently performed by individuals amonggroups on the water or on land. Birdsjostling for the highestposition on the rocksdisplayed Twitter-waggle constantly. It was alsoa majorpart of aquatic displays and was always a mechanism for increasing distance betweenbirds. On one occasionI watched, for 15 minutes, a singleSooty Guillemot continuouslyTwitter-waggle towards a group of communally

1 2 3 4 SECONDS

Figure6. Sonographsof (a) the Trilledsong of Cepphuscarbo (songvaries from 4 to 5 secondsin durationand alwayslacks the centralupslur most often includedby C. col- urnba). (b) the Trilled song of C. colurnba. (c) the Scream ("seeeee") of C. carbo, followedby four "tsits"or "chips."and (d) the "tsit"or "chip." the mostfrequent call heard in C. carbo. These "chips"are portrayedhere as a serieslasting more than 2 seconds.Most often "chips"are given well spacedand are heard in varyingsituations -- even m flight.

153 SOOTY GUILLEMOT bathingBlack-tailed . This bird was obviouslyattempting to drive the gullsaway, althoughthe gullsappeared to ignore it. Frequently, Twitter-wagglebegan by a bird distantlyremoved from a group which would swim quicklytoward the group, pickingon, it seemed, any individual that would turn and Twitter-waggleback towards it. An attackinglunge and fight often followed with the two birds splashing-- "Leap-frogging"(Asbirk 1979a, Preston1968) -- and divingjust below the surface.The rest of the groupjoined the subsurfacetwisting and turningas individuals,ending with skitteringover the surfacein all directions.This actiondispersed the groupstemporarily. The fightersmay continueto duel or they may fly from the scenein aerial chase. In the PigeonGuillemot, Drent (1965) calledthe water phaseof this actionthe "Water Dance", and the aerial chasethe "Duet Flight". However, the terms"Water Duel" and "Duel Flight" are preferred becausethey describethe activitiesmore accurately.Milling around on and under the water is not a dance, nor is an aggressiveaerial chase a duet, sincethe term "duet" impliessong. Duel Flight in guillemots resultsfrom an initialflight encounter started with Twitter-waggle.It should not be confusedwith a pair of birdsmerely flying together which is a common phenomenon among water birds in general. Duel Flight is an active duel between two birds in which the birds fly high and low frequentlycrossing each other'sflight paths. In the Sooty Guillemotthis duel sometimesended by fightingin the water amonggroups of otherguillemots as much as 0.5 km away from the initial encounter. The fight usually triggered communal subsurfaceWater Duelling by the new group: a confusionwhich tended to break up the fight. While in the air a bird being chasedmay turn its head and open its beak towardsthe chaser,but in mostencounters observed, Duel Flightwas merely a contest to outfly the other. Most frequently the duel ended when con- siderablespace developed between the two birds.In more than 100 sightings of Duel Flightamong Sooty GuillemotsI never witnessedactual contact in the air, suchas tail twigging,or sudden 180 ø turns with falls into the sea as are commonlydisplayed by the PigeonGuillemot. Erect Display as seen in the Sooty Guillemot is apparentlythe same as "Neck Stretch," as Nelson (1982) calls it, in Ceppi•u$ colurnt•a. I have also observed a similar stance in Tufted Puffins (Luncla cirri•ata) and Rhinoceros Auklets, which occasionallystand for a minute or more with their bills pointed upward. Accordingto D. Nelson (pers. comm.) Luncla, Fratercula, Ceror/•inca and Ceppi•u$ colurnt•aall vocalize during Erect Display. No vocalizationswere noted in C'epp/•u$carrio although I may have missedthe sounds.In the (Fraterculaarctica) the attitudeis accompanied by frequent Head-flicking,but in the Sooty Guillemot Head-flickingis rare and is much lesspronounced (Figure 7d). A strutterwaddied on land or when on water swam excitedly,toward the bird to which it displayed.Strutting accompanied by holdingthe wingsstiffly over the body (Wing-flagging)indicated a strongeraggressive action. This posturehas alsobeen describedin the BlackGuillemot which when on land embellishesthe action with a distinctivehigh steppinggait (Preston1968). Wing-flaggingdisplay may be moremeaningful in the BlackGuillemot which flasheswhite underwings.The Sooty Guillemotlacks white underwingsbut 154 SOOTY GUILLEMOT does occasionallyflag its wingswhen struttingand momentarilyas a flight- intention signal. In a nonsocialcontext the Sooty Guillemot may hold its wingsover the body for balancewhen walkingover rocks. Hunching is also an aggressiveapproach toward an intruder and is demonstratedby all three speciesof C'epp!•us(Figure 7c). The intruder usuallymoves away; otherwisea lungingattack occurs. Headbobbing,a rare display, I interpretedas a threat in the Sooty Guillemot. Headshaking, a side to side motion, as describedby Preston (1968) in the Black Guillemot, was not seen in the Sooty Guillemot.

Figure7. Displaysof the SootyGuillemot: (a) Squat-peepingor Hunch-whistle,(b) Twitter-waggle.(c) Hunching.and (d) ErectDisplay with Head-flicking.

155 SOOTY GUILLEMOT

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156 SOOTY GUILLEMOT

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157 SOOTY GUILLEMOT

Preston (1968) describedHeadturning display in the Black Guillemotas a turningof the billover or intothe scapulars.Pigeon Guillemots also Headturn (Nelsonin press).This displayoccasionally occurred in the SootyGuillemot. However, in over 300 observationsI was uncertainonly a few timesthat turn- ing the head toward the rear and tuckingthe bill in the scapularswas not associatedwith .Otherwise, Head-turning may be a signalfor ap- peasementtoward a Twitter-waggler. Bill and Head-dipping are habitscommon to all alcids,as well as to some other waterbirds,and are no lessfrequent in the Sooty Guillemot.I observed a singlebird activelyfeeding close to shore, and obviouslyHead-dipping to locate prey before diving to catch it. From about 2 m above, I could also see the fish in the clear water, which left me with no doubts as to the function of Head-dippingin that instance,for the bird peered under water to the right and left until it spieda fish then dashedafter it. However, disturbancesabove or below water also increasedthe frequencyand length of Head-dipping among Sooty Guillemots. For example, a cormorant swimming under a group of Sooty Guillemotsprecipitated bouts of Head-dipping. Increased Bill-dippingfrequency, a lesserbut more rapid responsewith only the bill in- volved often indicatedimpending flight.

SUMMARY A maximum of 400 birds made up the Teuri Island colony of Sooty Guillemotsin 1981. No more than half the populationdefended nestsand some of thesedid not rear young. Althoughtwo chickswere often hatched, no pairs were found to rear more than one chick. Three chickshatched at about 40 g and reachedas much as 605 g at 40 to 45 days of age before fledging. One fledglingwas seen daily for 16 days feeding alone close to shore.During this time itsplumage changed from sootyto mottledbrown, and its legsand feet from dark grey to red. Althoughbehavior patterns were similarto thoseof other speciesof Cep- phus, some displayswere lessenergetic than thosedemonstrated by related speciesat the samephase of the breedingseason. Behaviors accompanied by vocalizationsand other displayswere identified. Colonyattendance gradually changed to laterin the day as the seasonpro- gressed.No explanationwas discoveredfor this change.

ACKNOWLEDGMENTS Thanksare due to Dr. HisashiAbe of the Universityof Hokkaidofor ob- tainingthe necessarypermit for me to work in Teuri Island and for kindly hostingme at the Universityin Sapporo.Yutaka Watanuki gave unselfishlyof his time to work with me on logisticsand settingup camp on the island. Without his help this study would not have been possible.Matutoshi Aothuka, warden for birdson Teuri Island, also assistedby bandingchicks and by providingother information.Thanks are also due my wife, Shirley, who accompaniedme in the field and assistedwith recordingof data. An- drewsUniversity provided travel funds.

158 SOOTY GUILLEMOT

Zaravko and Bozana Stefanovic translated Russian literature and the helpfulcriticisms of DougNelson, Clare Lloyd and SpencerSealy greatly im- proved the initial drafts of this paper.

LITERATURE CITED

Ainley, D.G. & T.J. Lewis. 1974. The historyof FarallonIsland marine bird popula- tions, 1854-1972. Condor 76:432-446. Asbirk, S. 1978. Tejsten C'eppl•us grylle som ynglefuhl i Danmark. Dansk OrnithologiskForening Tidsskrift 72:161-178. Asbirk, S. 1979a. Some behaviourpatterns of the Black Guillemot C'eppl•usgrylle. Dansk OrnithologiskForening Tidsskrift 73:287-296. Asbirk, S. 1979b. The adaptivesignificance of the reproductivepattern in the Black Guillemot, C'eppl•usgrylle. Videnskabelige.Meddelelser dansk naturhistorisk Forening. 141:29-80. Austin, O.L. & N. Kuroda. 1953. The birdsof Japan: Their statusand distribution. Bull. Mus. Comp. Zool. 109:280-737. (1972 reprint). Cairns,D. 1978. Some aspectsof the biologyof the BlackGuillemot (C'eppl•us grylle) in the estuaryof the Gulf of St. Lawrence. M. Sc. thesis, Univ. Laval, Quebec. 91 pp. Cairns, D. 1979. Censusing hole-nesting by visual counts. Bird-Banding 50:358-364. Cairns, D. 1980. Nestingdensity, habitat structure, and human disturbanceas factors in Black Guillemotreproduction. Wilson Bull. 92:352-361. Cairns, D. 1981. Breeding, feeding, and chick growth of the Black Guillemot (Cep- piousgrylle) in southernQuebec. Canadian Field-Naturalist95:312-318. Dement'ev, G.P. & N.A. Gladkov. 1951. Birds of the Soviet Union, Vol. 2:196-281. Transl. by IPST, Jerusalem, 1968. Drent, R.H. 1965. Breeding biology of the Pigeon Guillemot, C'eppl•uscolurnba. Ardea 53:99-160. EnvironmentalAgency. 1973. Researchon birds and environmentalconditions on Teuri Island. EnvironmentalAgency, Japan. Pp. 63-81. (In Japanese). Follett, W.I. & D.G. Ainley. 1976. Fishescollected by Pigeon GuillemotsC'eppl•us ½olurnba(Pallas), nesting on Southeast Farallon Island, California. California Fish and Game 62:28-31. Hyde, L.B. 1936. Life cycle of the Black Guillemot(C'eppl•us grylle). 1st Ann. Rep. Bowdoin Sci. Star. 14-16. Hyde, L.B. 1937. Life cycleof the Black Guillemot (C'eppl•usgrylle). 2nd Attn. Rep. Bowdoin Sci. Stat. 30-33. Kozlova, E.V. 1957. , Suborder Alcae. Fauna of USSR: Birds. 2:1-140. Transl. Israel Progr. Scient. Transl. 1961. Kuroda, N. 1963. A survey of sea birdsof Teuri Island, Hokkaido with noteson land birds. Misc. Rep. YamashinaInstit. Zool. Ornithol. 3.5:61-81. Nazarov, Y.N. & V.I. Labzyuk. 1972. Some data on the biologyof the C'eppl•us ½arbo in the southern Primorye. Nauchnye Doklady vysshei shkoly. BiologischeskieNauki 15(3):32-35. (in Russian). Nelson, D.A. 1982. The communicationbehavior of the Pigeon Guillemot. C'½ppl•us colurnba.Ph.D. thesis,Univ. Michigan, Ann Arbor. 159 SOOTY GUILLEMOT

Nettleship, D.N. 1974. coloniesand distributionsaround Devon Island and vicinity. Arctic 27:95-103. Preston,W.C. 1968. Breedingecology and socialbehavior of the Black Guillemot, Cepphusgrylle. Ph.D. thesis,Univ. Michigan, Ann Arbor. Sealy, S.G. 1970. Egg teeth and hatching methods in some alcids. Wilson Bull. 82:289-293. Storer,R.W. 1952. A comparisonof variations,behavior and evolutionin the seabird genera Uria and Cepphus. Univ. CaliforniaPubl. Zool. 52:121-222. Thoresen, A.C. & E.S. Booth, 1958. Breeding activitiesof the Pigeon Guillemot, Cepphus columba (Pallas).Walla Walla Coil. Publs. Dep. Biol. Sci. 1-36. Winn, H.E. 1950. The Black Guillemots of Kent Island, Bay of Fundy. Auk 67:477-485.

Accepted 28 December 1983

Sooty Guillemot Sketch by Keith Hansen

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