Virst r d f Cap t (C 's fo Nrta me'ic
J. Brian Patteson alongthe axisof the Gulf Stream.We con- on the water no more than 15 m from the sideredthe water along the shelf edge to be M•ssHatteras. We observedthe bird closely P.O.Box 772 a blend of Gulf Stream water and Shelf as it rested on the water and studied it in water. flight on several occasions,as it would Hatteras,North Carolina 27943 Ihis blcndedseawater had been presenl flushwith the flockwhen we approached in the areafor severaldays and is some- within 10 to 15 m, and then resetde on the (eraall:[email protected]) what unusualfor mid-August,when the watera shortdistance away. After 20 min- Shelfedge south of CapeHatteras is often utes of continuous observation,the bird inundated with clear blue Gulf Stream flew off and was not relocated. 6eorgeL. Armistead water. Ihe blcnded water contained exten- sive wind-rowsof gulf weed (Sargassum DESCRIPTION AND IDENTIFICATION 523 EastDurham Street spp.) and was teemingwith baitfishand The Cape Verde Shearwaterwas clearly larger predatoryfish, includingDolphin smaller(by about20 per cent)and darker Philadelphia,Pennsylvania 19119 (Coryphacnahippurus), Wahoo (Acanthocy- above than the adjacentborealis Cory's biumsolanderi ), and White Marlin ( Tetrap- Shearwatersbut was otherwiseroughly (email:[email protected]) tums albidus). Many (Ariantic) Cory's similarin plumage,being countershaded, Shearwaters(Calonectris diomcdca borealis) brown above and mostly white below. and SootyTerns (Sternafuscata) fed along While at rest on the water. the bird'ssize, ABSTRACT these extensiveweed-lines, along with headcolor, and the color and pattern of the This papcr documcntsthe first North lesser numbers of Audubon's Shearwaters bill leto it an appearancestrikingly differ- Americanrecord of CapeVerde Shearwater (Puffinuslhcrminieri) and Bridled Terns ent from Cory'sand indeed from other (Catoncctriscdwardsii), a singlebird pho- (Stemaanacthctus), typical constituents of shearwaters with which we are familiar tographedoff North Carolina15 August the pelagic drift community.A single (Figures1-5). 2004, and providescontextual commcnts GreaterShearwater (Puffinus gravis) had Thecolor of thehead was clearly darker, on taxonomy,distribution, and fieldidenti- put in a briefappearance, and in tryingto a neutralgray as opposedto the warmer fication of Atlantic Catoncct•is taxa. relocatethat bird, we carefullyscrutinized brownor grayish-brownof the Cory's.The eachflock of Cory'sShearwaters as we trav- headlooked both smaller and more angu- FIELDENCOUNTER eled to the northeastalong the weed-line. lar than thoseof the Cory's,which have Overcastskies made it possibleto seewell larger,more rounded hcads, and its darker CONTEXT in all directions. color contrastedmore sharplywith the On 15 August2004, the authorsand 37 At 1042 EDT,Patteson spotted the Cape white of the lowercheeks and throat,giv- others aboard the Miss Hatteras observed a VerdeShearwater resting among a groupof ing the bird a more clcan-cutlook with Cape Verde Shearwater (Calonectris about 20 Cory's Shearwaters,and he colorsmore contrasting,less diffuse than edwardsit)near 34 ø 52.1' N, 75ø 22.2' alerted Captain Spurgeon Stowe to thc palerCory's Shearwater. The headand approximately49 km (26 nauticalmiles, approachthe flock more closelyand to bill werenot asdark as would be expeclcd 30 statute miles) southeast of Hatteras alerteveryone aboard to look for a slightly in Grcater Shearwater,and the bird did not Inlet, North Carofina.The waterdepth is smaller,darker bird in the flock.Though appearcapped, at leastwhen at rest. about 200 m at this location, near what is neitherauthor had previousfield experi- The rather slim, slender bill was consideredto bc the edgeof the Continen- enceof th•sspecies, Patteson had studied markedlyless bulbous than thoseof the talShelf. The sea surface temperature at the museumspecimens, and both authorshad Cory's;its color was dusky olive-gray at the time of our encounter was recorded as seenphotographs of it, anda closerlook at base, with a darker, blackish subterminal 26.9ø C. The minimumwater temperature the bird made them confident of its iden- bandand gray tip. The bill showedno pale recordedthat day was 23.7ø C, and the tity.Cameras were quickly brought to bear, ycllowishcolor, unlike the Cory's.At a dis- maximum was 29.1ø C farther offshore, so as to document the bird while it rested tance, the wide subterminal band made the
468 NORTH AMERICAN BIRDS Figure1. TheCape Verde Shearwater (left}off North Carolina stood out in the flockof about 20 Corfs 5hearwaters by virtueof its smaller size, colder plumage tones,sharper contrast of upperparts withunderparts, and smaller, shallower bill,which lacked the yellow tones of Cory's,being a more dusky olive in color. Allphotographs taken 15 August 2004. PhotographbyJ. Brian PatZeson.
bill lookdark-tipped. While thebird rested on thewater, •ts neck appeared rather thin, andthis gave the bird a somewhatdelicate aspect. comparedto Cory'sin the samefield of When bird took flight (Figures 6-9), view, but this was not noted in the field. its smaller size became even more obvi- The bird wasclearly in molt of both the ers (on an ATY bird), but this is not posi- ous, and though the bird was in what contourfeathers and the remigesand their ble in the held" appearedto be prebasicmolt (with both coverts. This full molt had commenced rel- Porter et al. (1997) describe six identifi- body and wing feathersin the midst of ativelyrecently, as •ndicated by the gapin cationfeatures to lookfor in differentiating being replaced), the upperparts as a the innerprimaries (pl-p4 weredropped), CapeVerde Shearwater from Cory'sShear- whole were clearlydarker than thoseof the missing distal greater upperwing water: the Cory'sShearwaters. The pale areaon coverts(exposing the white basesto the ß Bill noticeablythinner than Cory•, and the rump was less extensivethan in secondaries),and the disheveled look of grayor pinkish-graywith a blacksubtermi- nearby Cory's and contrasted more the plumagein the neck and back.Peter nal band (looking black-tippedat a dis- sharplywith the darkerupperparts. This Pyle studiedphotographs of the bird in tance),quite unlike the largeyellow (or mark is rather variable on Cory'sShear- flight and suggestedthat the broad, ivory)bill of Cory's; water;on this CapeVerde Shearwater, it roundedtips to the outerprimaries, the ßUpperparts darker and grayer brown than wasa thin pale,whitish crescem, lacking apparentabsence of retained(juvenal?) Cory's,with a dark 'W' (or 'M') often in warm color and nol as broad as on secondaries,and the probablepresence of noticeableacross the upperwings; Cory's,which are usually a dingy,pale off- retained lesser or median upperwing ß A clean demarcauon between the dark white, or evenbuff in color.In flight, the covertspoint toward a bird in its thirdcal- upperand whitelower parts of the head, bird appeareddarkcr ovcrall than Cory's elldaryc•T • •lAo• /--ACV.•t lo•ct') except for some pale patchesin the old). He writes:"An SY bird, roughlyone appearance; upperwing, where the shafts of the yearold, wouldbegin the primarymolt in ß Smallerand slimmer than Cory's,with a remigeswere exposedby moltedupper- June (assuminga schedulesimilar to that longertail, smallerhead, and slightly nar- wing coverts(see below). The underwing of Cory's)and be moltingp6-p7 by mid- rower wings: appearedsimilar to Cory's,being whitish August,would have browner and more ß Uppertail-covertstend to showconsis- with a brown border in the marginal pointedprimary ups, and would not show tentlymore white than Cory's; and coverts The uppertail coverts were older feathersof a previousgeneration. In ß Flightsimilar to Cory's,but with perhaps darker than in most Coryg. Subsequent hand, it might be possibleto assessthe lessdeep wing-beats and the wingsheld examinationof photographstaken of this retainedcoverts to seeif they arejuvenal slightlymore forward,with the hand at bird revealed a long-tailed appearance feathers (on a TY bird) or dehnitive [eath- right anglesto the bodywhen gliding.
VOLUME 58 (2004) NUMBER 4 469 We found all of these characters to fit with the North Carolina bird, aside from the fifth item, which we believe to be vari- able•n bothspecies, based on studyof pho- tographs,specimens, and birds in the field. When observedclosely. then. Cape Verde Shearwatershould not presentgreat diffi- cultyin identification.Porter et al. (1997) attestthat the first CapeVerde Shearwaters they encounteredlooked so differentfrom Cory• thatthey were initially puzzled as to whatthey were seeing, and theylikened its overalllong-tailed, narrow-winged appear- anceto Wedge-tailedShearwater (Pt•ffint•s pacificus).When seenpoorly or at a dis- tancehowever, identification could present a challengebecause Cape Verde Shearwater is comparablein structureand plumageto two commonspecies in the North Atlantic, Figure2. Cape Verde Sheanvater atcenter. Photograph byGeorge I. Armistead. Cory• and GreaterShearwaters.
DISCUSSION
STATUS AND DISTRIBUTION CapeVerde Shearwater is one of the least- studied species of North Atlantic tubenoses.The populationhas been esti- matedat 10,000pairs and is known only to breedon six islandsin the Cape Verde archipelago(Hazevoet 1995), although the "culling" of several thousandnestlings eachyear by local fisherman(Hazcvoet et al. 1996) could representa significant Figure3.Cape Verde Sheanvater atleft. Photogroph byGeorge I. Arm•steacl. threatto thisspecies, and its actualpopula- tion maybe smallerthan is currentlyesu- Santo,and the Desertas).It is mostly and Guinea-Bissau(Borrow and Demey mated. Cape Verde Shearwatersarrive at absentfrom watersaround the breeding 2001), and the specieshas been observed breedingislands beginning in late Febru- islands after November and before Febru- during its breeding months from sea- ary,with layingin Juneand July and fiedg- ary (Hazevoet1995). Dispersalat seahas watches in and around Dakar since at leasl ing in October and November (Hazevoe! not beenwell studied,but expeditionsto 1968 (Gaston 1970, Baillon and Dubois 1995), a schedulesimilar to, but slightly Senegalin Octoberof 1995and 1996found 1991, Marr and Porter1992, Allport 1995, earlier than, that of borealisCory's that it to be numerousoff thepeninsula of Cape Mart et al. 1998) and in adjacentwaters breed to the north, in the Azores, the Verde (within sight of land), and large (Brown 1979). Berlengas,the Canaries,the Salvages,and numberswere observedfeeding around Movementsof CapeVerde Shearwaters the MadeiranArchipelago (Madeira, Porto fishingtrawlers there (Porter et al. 1997). in the non-breedingmonths are essentially Thereare scattered winter reports of single unknown. It is surmised that the birds dis- birds off western Africa from Mauritania persesouth from the CapeVerde Islands
Figures2,3, 4. Ata distance, andat certain angles, when the Cape Verde Sheanvater (right, in Figure 4) wasseen sitting with Cory's, its smaller size, darker bill, and slightly darker plumage recalled GreaterSheanvater---or theeven smaller Manx Sheanvater, occasionally seenoff NorthCarolina inAugust. Greater Sheanvater isin fact larger than Cape VerdeSheanvater, with a darker(black) bill and a neatblack cap.
•m, Figure4. PhotographbyJ. Brian Patteson.
470 NORTH AMERICAN BIRDS into the southern North Atlantic 2004). and northern South Atlantic (Bor- More recently,Sangster et al. row and Demey2001). Awayfrom (1998) havesuggested that differ- Africa and related islands, we find ences between borealis and nomi- few reliablereports of this species. nate diomedeamerit species-level On 18 February1992, threeshear- distinction,but othersources sup- watersstudied off Argentinaat 38ø port subspecificrank (Wink et al. 36' S, 53ø 30' W were identified as 1993, Heidrich et al. 1996). Mor- Cape Verde Shearwaters(Curtis phologically,the forms are difficult 1994). In May andJune 1997, three to distinguish, and apparently CapeVerde Shearwaters were col- somegene flow occursbetween lectedoff the coastof Brazil (Petry the two taxa (Randi et al. 1989). et al. 2000), apparentlythe first Moregermane for the considera- documented occurrence for the tion of field identification is that Western Hemisphere,along with the Mediterranean-nestingnomi- winter sightingsoff Bahiaand Rio nate form (sometimes referred to deJaneiro/Sao Paulo, Brazil (Olmos as Scopoli's Shearwater) is a 2002; Olmos, pers. comm.). In smaller bird than borealis and thus North America,the only published closer in size to edwardsii. Even mentionof thisspecies is of a single the largest specimensof Cape bird, thoughtto be a likely candi- Verde Shearwater, however, are date for Cape Verde Shearwater, significantlysmaller than thoseof seenin a heavyshoreline migration the smallest Scopoli's(Hazevoet of Cory'sand Greater Shearwaters at 1995). Newell and TonyMart (in CapePoint, Buxton, North Carolina litt.) found that specimensof edwardsiiwere at least 10 per cent (Davis1993); this sightrecord pre- Figure$. Atmedium and close range, the dusky color of the bill and dark subtermi- smaller than those of cliomedea, cededthe recognitionof edwardsii nalband were apparent on the Cape Verde Shearwa•er. Despite its molt of body as a full species.We know of no feathers,the darker gray-brown crown and hindneck looked darker tban the that the depthof bill wasdifferent North Americanspecimens of Cape upperpartsofadjacent Cory's Shearwa•ers andcontrasted more sharply with (cliomedea = 12.5-13.5 ram; Verde Shearwater in museum col- thewhite underparts. PhotographbyfieorgeL. Armistead. edwardsii = 9.5-9.9 ram), and that lections. bill color and plumagecolors of Litre hasbeen published about the ages not fledgeuntil late in Octoberor earlyin nominatebirds were invariablyvery dose of Cory'sShearwaters, or the relativepro- November(D. Newell, pers.comm.), but to those of borealis but not to edwardsii. ponionsof their ageclasses, observed in no other publishedthoughts on agesof Thereare at leastfive extantspecimens of summer in the western North Ariantic. birds observed at sea are available. nominateCory's from eastern North Amer- Becauselarge numbers of Cory'sin varying ica (e.g., Levine 1998), but our limited states of molt are present through the TAXONOMY OF ATLANTIC reviewof specimenmaterial suggests that warmer months in and around the Gulf CALONECTRIS mostwestern North Atlanticspecimens are Streamoff the Carolinas,we have assumed Althoughwe hadexpected the detection of of the largerborealis (see also Lee 1995). theseto be birds not yet old enoughto thisspecies off North Carolina(see Brink- Birdsof the nominaterace, unlike borealis breedor possiblyadults that are not breed- ley 2000), we werenevertheless surprised andedwardsii, vary greatly in size,in a dine ing--all breedingcolonies are too distant at just how differentit was from Cory's fromlargest birds in the westernMediter- for foragingadults to makeregular trans- Shearwaterand further surprisedthat il ranean to smallest in the east (Hazevoet Atlanticflights to feedyoung. Mougin et al. had been consideredconspecific with 1995). Dick Newell and Richard Gutierrez (1997) reportedthat about 10 per centof Cory's.The first ornithologiststo describe (pers. comm.) suggestthat nominate breedingadult borealis in colonieson Sel- edwardsii,Oustalet (1883) and Alexander Cory'saverage smaller, more extensively vagemGrande do notbreed annually; most (1898, who called it Puffinusmarianae), paleon the underwing,and slightly darker absences(58%) arefor a singleseason, but bothaccorded it statusas a full species,as aroundthe head,with a lessbrightly pale somebreeding Cory's were found to be did Godman(1910) in A Monographof the yellowbill than borealis,but all of these absentfor up to sevenyears. Because of the Petrels.Later authors(e.g., Peters1931) charactersoverlap with someborealis, both strong natal philopatry in the species demotededwardsii to subspecificstatus, in specimensand in the field. The field (Rabouamet al. 1998), it is unlikely that thoughwithout evidence for therecatego- identificationof Cory'sShearwater taxa is suchhiatuses involve birds simply nesting rization.Murphy (1924) alsodid not rec- the subjectof much discussionon the elsewhere. Because of our limited know- ognizeedwardsii as a separatespecies but Internetand in birdwatchingpublications ledgeof moltschedules in Calonectris,and noted that "many ornithologistswould (Gutierrez 1998, Fisherand Flood 2004). becausethese "sabbatical"periods away unhesitatingly"do sobased on itsmanifest from the nestinggrounds are apparently differences,and Bourne (1955) concurred. DETECTION BIASES AND common,conjecture about movements of Hazevoet(1995) wasthe firstornithologist OTHER CONSIDERATIONS CapeVerde Shearwaters that mightbring in thetwentieth century to re-recognizethe Public birdwatchingexcursions in North some individuals closer to North American distinctivenessof edwardsiias a species, Carolina'spelagic waters differ from scien- waterswould be premature.Cape Verde basedon morphology(Granadeiro 1993) tific surveysof seabirdsin thatlittoral and Shearwatersseen off of Senegalin early and vocalizations (Bannerman and Banner- ContinentalShelf waters tend to gel less Octoberare in an advancedstage of pri- man 1968,Bretagnolle and Lequette 1990), scrutiny from birding boats. In recent mary molt and have been considered both of which differ from those of borealis years,pelagic efforts have focused more on subadultsor nonbreeders,as juveniles do and nominate Cory's (see also Soldat raregadfly petrels and storm-petrels, which
VOLUME 58 (2004) NUMBER 4 471 Figures6, 7,8, 9. Inflight, the active molt of coverts andremiges was apparent inboth the Cape Verde and theCory's Shearwaters. Inprofile, the Cape Verde Shear- waterwas dwarfed by the Cory's and often looked longer oftail and narrower ofwing; the wings looked narrower especiallyatthe base, but this could have been an effect ofmolting secondaries. Some of the impressions of shapevaried with flight style and attitude, as well as the angleof observation. Depending onthe lighting, the bird'soverall tones above seemed tovary from nearly as warmbrovm as Cory's to ratherdark, more like Greater Shearwater,and the appearance ofthe head might appearwashed out or even capped, though never so cleanlycapped asa Greater Shearwater.
Figure6. PhotographbyJ. Brian Porteson.
Point des Almadies,Senegal: recent news.Bulletin of theAfrican Bird Club 4: 55. BariIon,E, and Dubois, P 1991. Seawatch- mg from CapeVerde, Senegal. Birding World 4: 440-442. Bannerman, D., and W. Bannerman. 1968. becomeactive in salvagingstorm-wrecked Birdsof the AtlanticIslands: History of seabirdspecimens, particularly after hurri- the birdsof the CapeVerde Islands. Vol- canes,so that we may better understand ume 4. Oliver and Boyd, Edinburgh, the statuses of Calonectris shearwaters in UnitedKingdom. North American waters. Borrow,N., and R. Demey.2001. A Guide to the birdsof westernAfrica. Princeton Acknowledgments UniversityPress, Princeton, New Jersey. occurmostly in ContinentalSlope waters We wishto thank PeterPylc, Dick Newell, Bourne, V• R. P 1955. On the status and fartheroffshore. Consequently, little time Fabio Olmos, Richard Gutierrez, Richard appearanceof the racesof Cory'sShear- has been allotted to shearwater flocks, Porter,and E A. Buckleyfor theirvaluable water. Ibis 97: 145-149. whichtend to occurmostly on or nearthe contributionsto thispaper. We wouldalso Bretagnolle,V., and B. Lequette.1990. ContinentalShelf between spring and fall. like to thank SpurgeonStowe and the Structural variation in the call of the The samplingof pelagicbirds off of North crew of the Miss Hatteras as well as all Cory's Shearwater (Calonectris dio- Carolina has also been biased towards other participantsof the August15, 2004 medea,Aves, Procellariidae).Ethology morespring and early-summer trips, a time pelagictrip. 85: 313-323. when shearwaters are not as cmnmon as Brinkley,E. S. 2000. The next new ABA theyare m latesummer or fall. It is quite Area birds: Atlantic Pelagic-the Gulf possiblethat Cape Verde Shearwaterhas Literaturedted Stream.Birding 32: 136-145. escapeddetection on previousoccasions Alexander.B. 1898. An ornithological Brown, R. B. G. 1979. Seabirds of the whenlarge flocks of shearwatershave been expeditionto the Cape Verde Islands. Senegalupwelling and adjacentwaters. observed.Prior to the mid-1990s, most Ibis (7) 4: 74-118. Ibis 121: 283-292. seabirdersknew little if anythingabout Allport, G. A_ 1995_qeawatching from Curtis, W. E 1994. Further South Atlantic CapeVerde Shearwater, and an odd-look- ing shearwatermight have been passed off as a Greateror a Coryõ. A moreconcerted effort to studyshear- watersfrom August to Octobermight yield moresighungs of CapeVerde Shearwaters at a time when Cory'sand GreaterShear- watersreach peak numbers in Shelfwaters. It is alsopossible that tropical cyclones that originate in the eastern North Allantic could entrainsome CapeVerde Shearwa- ters and displacethem westward.Early August 2004 was a time of considerable tropical storm acuvity in the North Atlantic,and it is conceivablethat the Cape Verde Shearwater we observed was dis- placedby sucha storm.It is our hopethat more recordsof this specieswill cometo light as more observersbecome aware of the species and its identification: we encourageornithologists and birders to Figure7. CapeVerde Shearwater atleft. Plmto9roph byMo9nus Penmark
472 NORTH AMERICAN BIRDS in Brazil. Atlantic Seabirds 4: 77-80. Oustalet,E. 1883. Descriptiond'esp/:ces nouvellesd'oiseaux provenant des ties du Cap-Vert. Antiales des Sciences Naturelies(Zoologie) 16: 1-2. Peters,J. L. 1931. Check-listof birdsof the world.Harvard University Press, Cam- bridge,Massachusetts. Perry,M. V., L. Bugoni,and V. S. da Silva Fonseca.2000. Occurrenceof the Cape Verde Shearwater Calonectris edwardsii on the Brazilian coast. Bulletinof the British Ornithologists' Club 120: 198-200. Porter, R., D. Newell, T. Marr, and R. Joliffe. 1997. Identification of Cape Verde Shearwater.Birding World 10: 222-228. Rabouam, C., |.-C. Thibauh, and V. Bre- tagnolle. 1998. Natal philoparryand close inbreedingin Cory'sShearwater (Calonectris cliomedea). Auk 115: 483-486. Figure8. Photographby6eorge L.Arm[stead. Randi, E., E Spina,and B. Massa. 1989. records. Sea Swallow 43: 19-28. coast of North Carolina. Chat 59: Geneticvariability in Cory'sShearwater Davis, R. J. 1993. The spring migration: 113-171. (Calonectris cliomedea). Auk 106: SouthernAtlantic Coast Region. Ameri- Levine,E., editor.1998. BullõBirds of New 411-417. can Birds 47: 403-405. York State. Cornell University Press, Sangster,G., C.J. Hazevoet,A. B. van den Fisher,A., andB. Flood.2004. A Scopoli's Ithaca, New York_ Berg,C. S. Rosdaar.1998. DutchAvi- Shearwateroff the Islesof Scilly Birding Marr, T.. D. Newell, and R. Porter. 1998. [uanal list: species, concepts, taxo- World 17: 334-336. Seabirdsoff Senegal.Bulletin of the nomic instability, and taxonomic Gaston,A. J. 1970. Seabirdmigration off AfricanBird Club 1: 22-29. changesin 1998. Dutch Birding 20: Cape Verde, Senegal,in April, ]968. Mart, T_, and R. Porter. 1992. Spring 22-32. TheSeabird Group Report - 1970. seabird passageoff Senegal.Birding Soldat, E. 2004. Seabirdsskull gallery. Godman,E du C. 1910. A Monographo[ World 5: 391-394.
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