Swinhoe's Storm-Petrel

first northamerican photographic record

HICNAELO'BRIEN,* J. BRIANPATTESON,t DESCRIPTION GEORGEL. ARHISTEAD,and GRAYSONB. PEARCEõ Size,Structure, and Molt. The bird mostclosely resembled a Leach's Storm-Petrel.It wasof roughlythe same length as a Leach'sor Band- rumpedbut oftengave the impressionof beingslightly larger than birdingnAugust trip8, 1998,off Hatteras,the authors North were Carolina,participating aboard inathe pelagic Miss either. Its wingswere relatively long with an obviousbend at the Hatteraswith CaptainSpurgeon Stowe and 29 passengers.Winds carpaljoint or "wrist."It appearedproportionally longer-winged werelight from the southeast and seas calm. Over most of theprevi- thaneither Band-rumped or Leach'sand seemed to holdits wings in ousweek, strong northeasterly winds had createda strongcurrent a relativelyoutstretched position, much more akin to Band-rumped that apparentlypushed the Gulf Streammuch farther offshore than thanLeach's. Compared to Leach's,the wingswere narrower in the usualand brought cool water well south of CapeHatteras. Indeed we "arms"but longerand broaderin the "hands"and were not so did not run into warm water until 54 l•n out, about 16 l•n farther sharplypointed at the tips (Figures1, 2, 3). The net effectwas of seaward than usual, but when we arrived at the Gulf Stream'swest- morewing area in proportionto thebody than on a Leach'sor Band- ernwall, the seabirds were numerous. By early afternoon, the waters rumpedand, when the primarieswere spread,the wingslooked southeastof Hatterashad proven highly productive, with studiesof almostpaddle-shaped, very unlike Leach's or Band-rumped.In pho- Herald(Trinidade) Petrel (Pterodroma [a.] arrninjoniana)and South PolarSkua (Catharacta maccormicki), large concentrations of shear- tographsof the Swinhoe'swith a Band-rumped(Figure 4), the Swinhoe'sappears remarkably slimmer-bodied, which suggests that waters(Calonectris diomedea and Puffinusspp.) and Black-capped Petrels(P. hasitata),and a recordcount of Band-rumpedStorm- the fieldimpression of largersize in the Swinhoe'swas at leastpar- Petrels(O. castro)for that port. tiallyartifactual, probably owing to greateroverall wing area. None At about15:15 ED$•, shortly after we startedto headback shore- of usever had a firm impressionof tail shapein thefield, but pho- ward,we flusheda smallgroup of Oceanodromastorm-petrels off tographsseem to showa tail that is slimmerthan that of a Leach's the water,induding one with entirelydark uppertailcoverts and andwith a shallowernotch (Figures 1 and2). Althoughthe slim tail rump. Giventhe recentspate of Swinhoe'sStorm-Petrel records in gavethe bird a long-tailedlook in directflight (Figure 5), whenthe the northeasternNorth Atlantic (Bretagnolleet al. 1991,Cuhitt rectricesand primarieswere spread and the full wingarea revealed, 1995) and a sightrecord from North Carolinawaters (Brinkley the bird actuallylooked quite short-tailed (Figure 1). The flight 1995), togetherwith the fact that dark-rumpedLeach's Storm- featherslooked full, with no obviouslymissing feathers, though in Petrels(O. leucorhoa)have yet to be documentedin the Atlantic somephotographs (Figures 1 and 5) the outerprimaries look more Ocean basin (see below), we suspectedthe bird might be a wornthan the inners, suggesting that the bird was midway through Swinhoe's.We pursuedthe bird to the southwestfor about 11 km primarymolt. Judgingfrom photographs(Figures 6, 7, and8), the overa 40-45minute period in anattempt to obtainphotographs and primarycoverts seem to befull aswell. Foradditional images of this betterviews. The bird remainedin flightfor theentire observation, individual,consult Patteson's website at http://www.patteson.com. but CaptainStowe occasionally brought us to within about 25 Coloration.The overallcolor was dark grayish-brown, darkest on metersof the bird, allowingreasonably good views. During this the uppertailcoverts and rump and slightly paler on theupper back time, we obtainedabout 150 photographsof the bird and noteda and nape.The tonewas similar to that of a Leach'sbut obviously combinationof plumage,structural, and flightcharacters that con- palerthan that of a Band-rumped.In photographs,the head appears firmed the identification as Swinhoe's Storm-Petrel. On several to be contrastinglygrayer (Figures 8 and 9), thoughthis was not occasionswe flushedother storm-petrels and, for briefperiods, had notedin thefield. The pale upperwing covert bar or "carpalbar" was Wilson's(Oceanires oceanicus), Leach's, and Band-rumpedstorm- veryobvious, as on a Leach's,and it broadenedmarkedly toward the petrelsflying alongside the Swinhoe's for directcomparison. leadingedge, as on that species(Figures 2, 5, 6, and 8). Fromabove, The bird wasinitially found at 34ø37'05"N, 75ø18'30- W, about the outer severalprimaries appeared to have somewhite toward 68.6 km south-southeastof Hatteras Inlet, in water 2378 meters theirbases, though it wasvery inconspicuous and only visible when deep,and was pursued to 34ø32'00"N, 75o25'45"W, about77.8 km thebird wasat itsvery dosest (about 25 m). Wehad this impression south-southeastof Hatteras Inlet, in water2378 m deep.Sea surface especiallyas the bird banked,perhaps because it spreadthe pri- temperaturein thesewaters ranged from 28.8 to 29.2ø C. For most mariesfarther apart but no doubtalso because the wing motion was of theobservation, distances from the bird rangedfrom about 50 to slowestthen. Had we not lookedspecifically for whitein the pri- 75 m. Lightingconditions ranged from goodoff the port bow to maries,it probablywould have gone unnoticed. Photographs con- harshand backlit off thestarboard bow, but CaptainStowe was able firm thatthere is a veryrestricted white patch at thebase of theouter to keepthe bird in goodlight most of the time. primaries,visible in both spreadand folded wing positions (Figures * E0.Box 436, Cape Nay Point, New Jersey 08212; t RO.Box 772, Hatteras, North Carolina 27943 $ 25124•t FerryNeck Road, Royal Oak, Naryiand 2! 662; õ 338Faire Chase, Chesapeake, Virginia 23322

6 NORTH AHERICAN BIRDS Michael O'Brien Figure 1 Michael O'Brien Figure2 J. BrianPatteson Figure3

I. BrianPatteson Figure4 I. BrianPatteson Figure5

MichaelO'Brien Figure6 GeorgeL. Armistead Figure7 GeorgeL. Armistead Figure8

FiguresI to 9. In thesephotographs, most of the generalproportions and plumage charactersof this Swinhoe'sStorm-Petrel can be discerned.Figures 1, 2, and 3 showthe overallshape of the bodyand wings fairly well: the baseof the wingappears a bit narrowerthan in Leach's,whereas the primaryarea looksa bit broaderin comparison. In Figure4, whereSwinhoe's is picturedwith a Band-rumped,the formerlooks somewhat slimmerof body,perhaps owing to the impressionof greaterwing area. Impressions of tail lengthvaried from long (Figure5) to rathershort when the wingswere extended (Figure1). Figures6, 7, and 8 showa hirdwith intact,full primarycoverts, though Figures1 and 5 suggestthat the outerprimaries are moreworn than the inner (possibly newer)primaries. The dorsalsurface of the birdwas largelyflat brown,set off by a pale carpalbar (Figures2, 5, 6, and8). Othenvise,the onlypale pigmentationon the bird consistedof a patchat the visiblebase of the primaries(Figures 6, 8, and9).

Michael O'Brien Figure9

VOLUME53 (1999)t ISSUEI 7 6, 8, and 9). Whetherthis white patchis confinedto the primary Howeverthey arrive in the Atlantic,the intriguingquestion shaftsor includeswebbing isnot possible m determine. remainsas to whetherthese Atlantic Swinhoe's are breeding. It has FlightStyle. The flight styleseemed distinct from both Leach's beensuggested that a smallbreeding population of Swinhoe'smay and Band-rumpedstorm-petrels. The wing strokeswere relatively existsomewhere in the northeasternAtlantic (Cubitt et al. 1992),but slowand "loping" (not snappy)and the flightwas quite steady and asyet none has been discovered. Interestingly, of thebirds that have direct,not unlikethat of a tern.It lackedthe nighthawk-like erratic been captured,several have possessed vascularized brood patches, bounding,quick directionchanges, and side-to-siderocking of whichwould appear to lendmore weight to suspicionof localbreed- Leach'sor at leastthese patterns were very much reduced from those ing (Parkin& Cubitt1995). Also, an apparentmorphometric diver- of Leach's.Though the wing strokes were deep, they were shallower genceexists between Atlantic and PacificSwinhoe's Storm-Petrels, with the Atlanticbirds showinglarger wing chordmeasurements thanthose of Leach's,not risingas high on the upstrokeand seldom (Cubittet al. 1992),though, as Cubitt (1995) notes, this conceivably exhibitingthe deep"V" sotypical of that species.The glideswere on couldbe explainedby differencesin the recordersand/or their mea- bowedwings as in Leach'sand Band-rumped,but the glideswere suringtechniques. DNA analysishas found Atlantic Swinhoe's to be longerthan those of Leach's(usually one-two seconds). Compared to geneticallyinseparable from Pacific birds (Dawson 1992), which sug- Band-rumped,the wing strokeswere deeperand slowerand the geststhat they are relatively recent visitants from the core population, glidesprobably averaged shorter. How much the bird's flight patterns perhapsprospecting new nestingareas, and that AtlanticSwinhoe's wereinfluenced by pursuit is not known, but onewould expect a bird probablyhave not been long isolated from Pacific populations. to movefaster and more directly while being chased. We do,however, oftenchase Leach's and Band-rumpedstorm-petrels on pelagic IDENTIFICATION tripsand have never seen one exhibit a similarflight style. We should AlthoughLeach's Storm-Petrel is clearlythe mostsimilar species to notealso that, after following the bird for a while,it graduallyshift- Swinhoe'sand, in fact,the two have been considered conspecific in the edto longerglides and shorter periods of flapping,increasing its dis- past(Huntington et al. 1996),a wholesuite of speciesmust be con- tinction from Leach's. sideredin determiningthe identity of theNorth Carolina bird. There are eight all-darkstorm-petrels within the genusOceanodroma, STATUS AND DISTRIBUTION includingMatsudaira's (0. matsudairae),Leach's, Markham's (O Swinhoe'sStorm-Petrels occur primarily in the westernPacific and markhami),Tristram's (0. tristramO,Swinhoe's, Ashy (0. homochroa), northernIndian Oceans.Breeding takes place on islandsoff Russia, Black(0. melania),and Least(0. microsoma).All sharewholly dark Japan,Korea, China, and Taiwan, with egg-layingbetween May and plumage(with the exception of thosesubspecies of Leach's that show August(James & Robertson1985). These birds migrate south and a variablewhite rump patch)and a variablyprominent pale upper- westthrough South China Sea and at leastsome travel as far asthe wingbar. Bulwer's Petrd (Bulweria bulwerii) is similar enough to war- northern Indian Oceanand Red Sea(Harrison 1987). rant considerationas well, but thisspecies and Least Storm-Petrel (in The first fully documentedrecord of Swinhoe'sStorm-Petrel additionto pronounceddifferences in proportionsfrom Swinhoe's) fromthe Atlantic Ocean came in Juneand July 1983, when a birdwas bothhave wedge-shaped tails that should easily rule them out. tape recordedand later capturedin the nestchamber of a Band- Havinghad the advantageof watchingthe North Carolinabird rumped Storm-Petrelon Great SalvageIsland, Madeira (James& side-by-sidewith Leach's,Band-rumped, and Wilson's storm-petrels, Robertson 1985, Cubitt et al. 1992). Prior to that, there was an wewere able to geta goodfeel for itsrelative size and proportions In intriguingrecord from 1829of a smalldark storm-petrel type with a directcomparison, the bird wasnot obviouslydifferent in sizefrom forkedtail capturedat the samelocation (Heineken 1829), a birdthat Leach's,though it hadat leastthe illusionof beingfractionally larger mayhave been a Swinhoe's.Since 1983, at leasteight more Swinhoe's andlonger-winged, perhaps owing to its apparentlygreater "hand" Storm-Petrelshave been captured under similar circumstances at the areaand to its tendencyto hold its wingsmore outstretchedthan Salvagesand in France(Bretagnolle et al. 1991),England (Breta- Leach's.There is clearlya marginof errorin makingestimates of size gnolleet al. 1991),Norway (Gantlett 1997 & 1998a),and Portugal in thefid& Manyfactors such as flight style, wing shape, and overall (Gantlett1998b). Amazingly, one individual at Tynemouth,England proportionscan influence the apparentsize of a birdin the field,and was capturedeight times between1990 and 1994 (Cubit 1995). of courseeach species exhibits a rangeof measurements.However, Additionally,there have been two capturesin the Mediterraneanin underthe conditionsof this observation,size alone provided a solid Spain(King & Minguez1994) and Italy (Gantlett 1997). Along with meansof rulingout all but Leach'sand Swinhoe's. Even at a glance,a thesecaptures, there have been a numberof sightingsat seaor from Matsudaira's,Markham's, Tristram's, or Blackstorm-petrel should land-basedseawatches in Europe of dark-rumpedstorm-petrels, appearobviously larger than Leach's in the fieldand Ashy obviously mostof whichare now presumedto be Swinhoe's(Bretagnolle et al. smaller,particularly to experiencedseabirders familiar with mostof 1991,Bourne 1992,Morrison 1998).The most famousof theseis the the easternNorth Pacificspecies. Using average wing chordmea- "Chalicepetrel" seen August 3, 1988,off Cornwall,England (Gantlett surements(in Cubittet al. 1992)as a gaugeof apparentsize, Black 1988),the identificationof whichhas been hotly debated over the and Markham'sshould each be 12 percentlarger than nominate pastdecade (e.g., Bourne1997, Hume 1997, Young and King 1997, Leach's,Tristram's 14 percentlarger, Matsudaira's 19 percent larger, Force 1997). andAshy 12 percent smaller. How Swinhoe's Storm-Petrels arrive in the Atlantic Ocean is To put the usefulnessof relativesize in perspective,we'll usethe unknown.It is plausiblethat they eitherpass around the Capeof exampleof Leach'svs. Wilson'sstorm-petrels, two specieswe see GoodHope and north into theAtlantic or arrivefrom the northern togetherfrequently off North Carolina.Although there are times Indian Ocean via the Red and Mediterranean Seas (James & whenthe largersize of a Leach'sis lessthan obvious,particularly Robertson1985). The recordsfrom the Mediterraneanoff Italy and whenviews are brief or distant,in prolongedstudy, the sizediffer- Spainand one from Eilat,Israel (King & Minguez1994) lend cre- enceis alwaysreadily apparent if not striking.From wingspan mea- denceto the lattertheory. surementsin Harrison(1987), Leach'sStorm-Petrel should appear

8 NORTH AHERICAN BIRDS SWINflOE'S STORM-PETREL about13 percentlarger than Wilson's, and we feelthat anysize dif- Thefeature that initiallybrought our attention to thisbird was its ferenceof evenhalf that magnitudewould have been readily dis- entirely,unambiguously dark rump. Whether nominate Leach's can cernibleinthe prolonged views we had, which included side-by-side show an entirelydark rump is a matterof somedebate but, to date, comparisonwith Leach's,Band-rumped, and Wilson's. no suchbird hasbeen documented. The authorshave collectively Tail shapeis anotherfeature that rulesout all but Leach'sor seen hundreds of Leach's Storm-Petrels in the North Atlantic show- Swlnhoe'sand strongly suggests Swinhoe's. Matsudaira's, Markham's, ing a widerange of rump patterns.Not a few exampleshave shown Tristram's,Black, and Ashy all showobvious deeply forked tails. In completelywhite rumpswith no apparentdark centraldivision, Leach's,the tail fork is shallowerand sometimeshard to see in the whereasat leastone individual off OregonInlet, North Carolinain field The tail fork of Swinhoe's has been described as shallower than July1991 showed little more than pale grayish-white outer fringes to that of Leach'sby Kingand Minguez (1994) and difficultto seeby the rump (M. O'Brien,pers. obs.). The latter individualindeed Ent•cottand Tipling (1997), and Peter Hayman's excellent drawing in lookeddark-rumped at first and generatedquite a stir on the boat Cub•tt (1995) showsa tail fork of abouthalf as deepas that of a untilbetter views were had. With thisdegree of variationin therump Leach's.The North Carolinabird's tail appearedto be moreshallow- patternof nominateLeach's, it wouldnot be surprisingto find an ly notchedthan that of a Leach's(Figures 1 and 2) and clearlynot examplewith a completelydark rump. Bourne and Simmons (1997) consistentwith the deeplynotched tails of anyof the dark-rumped documentthe occurrenceof a single"dark-rumped" Leach's Storm- storm-petrelsother than Leach's or Swinhoe's. Petrel in the South Atlantic, but their basis for this claim is a 1964 Within the genusOceanodroma, the presenceof whiteprimary specimenfrom southeast of St.Helena that actually shows patches of shaftsbeyond the covertshas been widely cited as limited to Matsu- paleplumage on thesides of therump, a birdthat resembles birds we dalra'sand Swinhoe's storm-petrels (e.g., Cubitt 1995). Though it•was haveseen off North Carolinaand thatwould be apparenton a bird difficultto seein the field,photographs of the North Carolinabird at sea,given any reasonable study. Bourne and Simmons (1997) also showdistinct whitish patches at thebase of the outerprimaries, evi- referto a dark-rumpedspecimen (no longerextant) from anAugust denflythe result of white-basedprimary shafts (Figures 6, 8, and9). 1933wreck of Leach'sStorm-Petrels at OneidaLake, New York(Bird- However,David Sibley (in an internetposting to the groupBIRD- Lore35 [1933]:320), though Brinkley (pers. comm.) points out that WG01 [Frontiersof FieldIdentification], 1 Dec. 1998) points out that thespecimens from this wreck may have been in suchpoor condition someBlack and Leach's storm-petrels (perhaps five percent) can show that theirtail covertswere absent. The onlyNorth American reports whiteprimary shafts, occasionally forming an obviouspatch visible at of dark-rumpedLeach's known to usare of a bird off PortO'Connor, a &stance.Indeed, white-based primary shafts are visible in published Texas(Lasley et al. 1998;G. Lasley,pers. comm.), which actually had photographsof Blackand Tristram'sstorm-petrels in Enticottand a dingywhitish rump patchconsistent with nominateLeach's, and Tipling(1997), and at leasta suggestionof white-basedprimary shafts anotheroff Myrtle Beach,South Carolina (Davis 1998; J. Peachey, is wsiblein photographsof Band-rumped(the Englishcommon pets.comm.), which was seen well and described as completely dark- namedused in thistext is "MadeiranPetrel") and Markham'sstorm- rumped,but the detailsof thissighting do not eliminateSwinhoe's petrelsin Harrison(1987). Also, a specimenof Markham'scollected Active seabird researchers in the western North Atlantic have never off Peruhas whitish primary shafts (M. Force,unpub. ms.). Despite seena dark-rumpedLeach's (though R. R. Veithas noted One with a th•scautionary note, specimens show that visible white primary shafts "ghost"image of a rump patch;pers. comm. to Brinkley),and beyondthe primary coverts are typical of Swinhoe'sbut rare at bestin researchin Atlanticcolonies has never revealed a dark-rumpedindi- Leach's.We examined 41 Leach'sspecimens (including 22 beali,13 leu- vidual(C. Huntington,pers. comm.). So, without firm evidencethat corhoa,three socorroensis, and threeof tinknownsubspecies) at the nominateLeach's can showan entirelydark rump, a fully dark- Academyof NaturalSciences and found that noneshowed primary rumpedbird in theAtlantic Ocean should not be presumeda Leach's shaftsthat were white or evenslightly pale beyond the primary coverts. andshotfid be criticallyexamined for Swinhoe's. Althoughthe verybases of theseprimary shafts are indeed whitish, The dark-rumpedforms of Leach'sStorm-Petrel obviously pre- theyshade quickly to grayish,then brown, and the primarycoverts sentthe mostcomplicated and difficult identification problems. Five extend5 to 7 mmbeyond any pale coloration. Clearly then, although subspeciesof Leach's are currently recognized, including O. I. leucor- a traceof whiteat thebase of theprimaries, especially when seen poor- boa,O. I. beali,O. I. chapmani,O. I. socorroensis,and O. I. cheimom- ly, shotfidnot be considereddiagnostic for anystorm-petrel, it is cer- nestes(Huntington et al. 1996).Of these,only the smallersocorroen- tainlymore typical of Swinhoe'sthan Leach's. It is importantto note sisand chapmani are comprised largely of dark-rumpedindividuals. thaton theNorth Carolina bird, the primary coverts were full (Figures The largerof these,chapmani, exhibits wing chord measurements of 6, 7,and 8), sothe bases of theprimaries were not more exposed than 139to 155mm (Huntingtonet al. 1996)compared to 142to 171for usual.It shouldalso be bornein mind that intenselighting at seacan leucorhoa(Huntington et al. 1996) and 148 to 167 for Swinhoe's oftencreate the illusion of paleprimary shafts. We have had this fleet- (Cubittet al. 1992).Although Swinhoe's shotfid be aboutthe same mgimpression of paleor whitishprimary shafts in manytubenoses at sizeas nominate Leach's, birds captured in the North Atlantichave seabut, most importantly, in speciesthat show no paleprimary shafts beenas much as five percent larger (Brinkley 1995). Thus there is in the museumtray or in photographs.We believethat the discrete overlapin sizebetween Swinhoe's and chapmani, but it is important whitepatches visible at thebase of theprimaries in photographsof the to realizethat the North Carolinabird wason the largerend of the NorthCarolina bird (Figures 6,8, and 9), differ subst.antially from the spectrumfor leucorhoa(and Swinhoe's) while chapmani only over- filuslonof whiteshafts created by transienteffects of light.Under lapswith the smallerend of the leucorhoaspectrum. The sizeof the othercircumstances, wear or molt in greaterupperprimary coverts North Carolinabird is,therefore, consistent with Swinhoe'scaptured exposesthe pale bases of theprimary shafts (in manyseabird species), in theAtlantic but largerthan most if not all dark-rumpedLeach's. or theworn (and therefore paler, in a darkseabird) inner webs of the Afterwatching this bird for over40 minutes,there was no doubt primariescan be, very easily,mistaken for the shaftof the primary in our mindsthat the bird observedon August8 wasnot a Leach's itself Finally,seabirds that havepatches of leucisticfeathering may Storm-Petrel.Although the dark rump and whitish patch at the base havea tendencyto havepartially amelanistic primary shafts of the primarieswere sufficientto hold our attention,the most

VOLUME53 (1999), ISSUEI 9 arrestingdifferences from Leach'sinvolved the bird'sstructure and ingflight to bevery much like that of Leach's,he described Swinhoe's flightstyle. The relativelynarrower arm andbroader, more bluntly- asexhibiting a moredirect flight with stiff,shallow wingbeats and lit- pointedhand created a wingshape (almost paddle-shaped when the tle changein directionor altitude,under light winds. The lattercon- primarieswere spread) very unlike any Leach'swe haveever seen. ditionsprevailed on August 8, andthe storm-petrel observed on that Thiswing shape also created a relativelylarger wing area which was dateconforms well to thecharacters described in Force'smanuscript. exaggeratedby the slimbody and tail, increasingthe bird'sdistinc- Interestingly,Force was neverable to seewhite primary shafts(of tion from Leach's.Likewise, the slow,"loping;' and relativelyshal- well over100 Swinhoe's observed at sea),although he notesthat the lowerwingstrokes, the longer glides, and generally more direct flight birdsrarely approached closer than 100 metersfrom the ship.All collectivelyproduced a flight patterninconsistent with any Leach's Swinhoe'she collected,importantly, did exhibitfour or fivewhite- we haveencountered, including those we havechased. Although the basedprimary shafts. flight styleof PacificLeach's (including dark-rumped forms) has been described as somewhat more subdued than that of Atlantic ACKNOWLEDGMENTS birds(R. A. Rowlett,pers. comm.), it is still decidedlyerratic and is We thankEirik A. T. Blom,Richard Crossley, Ricky Davis, Shawneen Finne- gan,Steve Gantlett, Greg Lasley, Paul E. Lehman,Paul O'Brien, Jack Peachey, appropriatelycharacterized as ricocheting by Stallcup(1990). andRichard A. Rowlettfor providinginformation that strengthenedthis arti- MichaelForce, who hasextensive experience with Swinhoe'sin cle.We alsowish to thankCaptain Spurgeon Stowe for hiscamaraderie and the westernIndian Ocean (unpub. ms.), notes that size,shape, and hissuperb boatwork, which allowed us to studythe Swinhoe's Storm-Petrel at flightstyle are the mostuseful characters for fieldidentification. He length.As ever, a voteof thanksis dueall the participantson that excursion, withoutwhom it wouldnot havebeen possible. emphasizeshow Swinhoe's,compared to Leach's,looks relatively long-wingedand short-tailed. Although on theNorth Carolina bird LITERATURE CITED we onlygot a short-tailedimpression when the flightfeathers were Bourne,W. R. P.1992. Dark-rumped storm-petrels in theNorth Atlantic. Sea spread(Figure 1), the wings always looked longer than those of near- Swallow 40: 62-63. byLeach's, and the total wing area made the body as a wholelook rel- Bourne,W. R. P.and K. E. L. Simmons.1997. A dark-rumpedLeach's Storm- ativelysmall. Because of thislarge wing-to-body ratio and because Petrel Oceanodroma leucorhoa in the South Atlantic. Sula 11: 209-216. Bourne,W. R. P.1997. The Chalicepetrel. British Birds 90: 527. therectrices were usually held tightly closed, the taft usually did look Bretagnolle,V., M. Carruthers,M. Cubitt,E Bioret,and J.-P. Cuillandre. 1991. relatively"small" if not necessarilyshort. Force also refers to broader, Sixcaptures of a dark-rumped,fork-tailed storm-petrel in the northeast- morerounded wings held straight out fromthe body (contributing ern Atlantic. Ibis 133: 351-356. to the long-wingedimpression), and this descriptionmatches the Brinkley,E.S., 1995. Dark-rumpedstorm-petrels in the North Atlantic. Birding27: 95-97. North Carolinabird well (and is consistentwith the descriptionof Cubitt,M., M. Carruthers,and E Zino. 1992.Unraveling the mysteryof the the 1993Swinhoe's as well [Brinkley1995]). Although Force describ- Tynepetrels. Birding World 5: 438-444. ed the flightstyle of Swinhoe'sunder windy conditions or in forag- Cubitt,M. 1994.The mystery dark-rumped storm-petrel. Birding 26: 125. Cubitt,M. 1995.Swinhoe's Storm-Petrels at Tynemouth:New to Britainand Ireland. British Birds 88: 342-348. Davis,R. 1998.Southern Atlantic Coast Region Report. Field Notes 52: 45-48. Dawson,R. 1992.Blood, sweat and petrels. Birding World 5: 443-444. Enticott,l and D. Tipling.1997. Seabirds of the World.Stackpole Books. NorthAmericafi Birds Force, M. 1997.Comments on the 'Chalice'petrel. British Birds 90: 339-342. Gantlett, S. 1988. Matsudaira's Storm-Petrel off Cornwall: A New British Bird. BirdingWorld 1: 285. Gantlett,S. 1997.1996: The Western Palearctic Year. Birding World 10: 19-33. [Field Notes] Gantlett,S. 1998a.1997: The Western Palearctic Year. Birding Worm 11: 21-35. Gantlett,S. 1998b.Western Palearctic News. Birding World 11: 252-257. Harrison,P. 1987.A FieldGuide to Seabirdsof theWorld. The StephenGreen ßTap into North America'slargest Press.Lexington, Massachusetts. Heineken, C. 1829. Notice of some of the birds of Medeira. Brewster• birder network Edinburgh]. Sci.,New Series I: 229-233. Hume,R. A. 1997.From the RaritiesCommittees Files: The 'Chalice'petrel. ßShare your sightings with otherfield birders British Birds 90: 305-313. Huntington,C.E., R.G. Butler,R. A. Mauck. 1996. Leach'sStorm-Petrel ßSee the mostexciting birds in color (Oceanodrornaleucorhoa) in The Birdsof North America,No. 233 (A. Pooleand E Gill,eds.) Academy of NaturalSciences, Philadelphia, and the ßUnderstand trends in migration,nesting, AmericanOrnithologists Union, Washington, DC. lames, P. C., and H. A. Robertson.1985. First record of Swinhoe'sStorm- rangechanges, and more. Petrel Oceanodrorna monorhis in the Atlantic Ocean. Ardea 73: 105-106. King, l., and E. Minguez. 1994. Swinhoe'sPetrel: The first Mediterranean Fourissues for just$20 in the U.S. record.Birding World 7:271-273. Lasley,G., C. Sexton,M. Lockwood,C. Shackelford,and W. Sekula.1997. The $25 (USD) Canada/International fall migration:Texas region. Field Notes 52: 86-92. Morrison,S. 1998.All-dark petrels in the North Atlantic.British Birds 91: Specialrates for ABA Members 540-560. Stallcup,R. 1990.Ocean Birds of the NearshorePacific. Point ReyesBird Observatory,Stinson Beach, California. Young,S. A., and I. R. King. 1997.The 'Chalice'petrel revisited. British Birds 90: 329-335. (800) 850-2473 www.americanbirding.org

10 NORTH AMERICAN BIRDS