Reassessmentofa frigatebird recordfor Wyoming: LesserFrigatebird (Fe ataa iel)
DOUGFRULKNER ß DEPARTMENT OFZOOLOGY AND PHYSIOLOGY ß UNIVERSITY OFWYOMING ß LARAMIE, WYOMING ß (EMAIL: [email protected])
not a speciesnative to the state,the rehabili- tatorwas compelled to disposeof it in thelo- callandfill due to wildliferegulations regard- ing storageof non-gamebirds. During this period,it was reasonablyas- sumedto be a MagnificentFrigatebird (F. magniJ'icens),and the record, along with all of thephotographs presented here, was submit- ted as that speciesto the WyomingBird RecordsCommittee. The Committeeformally acceptedit asthe first state record of Magnif- icentFrigatebird (file WBRC #03-002). Reassessmentof the photographs In lateJune 2006, whileworking on a major publicationupdating the statusand distribu- tionof Wyoming'saviEauna, I asked the Cody wildlife rehabilitatorabout the Magnificent Frigatebird.She sent a singlephotograph (Fig- ure 1) showingthe bird• dorsalaspect post- mortem and mentionedthat more photo- graphswere submitted along with therecords committee documentation. Several features immediatelylooked wrong to me for Magmfi- cent:the reddish orbital ring, pink bill, and es- peciallythe whitecollar with rustytinge on the hindneck. I consultedHarrison (1985), and,after finding that Magnificent d•d not ex- hibit any of those characteristicsin any age/sexcombination. I contacted the records committee'sSecretary [or the remainingpho- tographs.I sent these images to several seabird biologists,who confirmed the identification as Abstract Field encounter an adultfemale Lesser Frigatebird (F. ariel). This paper establishesthe third record On 11July 2003, a WyomingGame and Fish (chronologically,the secondrecord) [or Departmentbiologist discovered a severely Identification NorthAmerica of LesserFrigatebird (Fregata emaciatedfrigatebird (Fregata) lying on the As Brennan and Schultz (2006) mention re- ariel), an adult female found emaciatedand groundnear the town of Basin,Big Horn gardingtheir analysis of a LesserFrigatebird in near deathon 11 July 2003 near Basin,Big County,Wyoming. He pickedup thebird and Michigan,it is importantto determineage and Horn County,Wyoming. Details surrounding delivered it to a wildlife rehabilitation clinic sexof anyfrigatebird before trying to establish the originalencounter, the birdgdemise and in Cody,where the bird diedwithin an hour a specificidentity. Fortunately, the available finalresting place, reassessment of documen- of its arrival. Prior to and after its demise,sev- photographsofWyomingõ frigatebird are of an tary photographs,separauon from other eral photographswere taken (Figures1-3). in-handor deceasedbird, and several diagnos- species,and weatherconditions possibly re- The birdwas promptly placed in therehabili- tic features are shown in close &taft. sponsible[or thisbird's presence in Wyoming tation centerg freezer.Later, when the local Ihere are five frigatebirdspecies world- are discussed herein. museumre[used the specimenbecause it was wide Ascension(E aquila),Christmaq I•-
328 NORTH AMERICAN BIRDS REASSESSMENTOFAFRIGATEBIRD RECORD FORWYOMING 1
land (E andrewsO, Great (E minor), Lesser, Wyomingbird. In addition,the size of thisfe- Wyomingis perhapseven more remarkable and Magnificent.All five sharesimilar basic malefrigatebird in comparisonwith a stan- than the two other North American records, plumagefeatures that more or lesscharacter- dard-sizednewspaper (56 cm;cf. Figure 3) is giventhe stateglandlocked location in west- ize age and sex classes.Using these basic toosmall to be anvof the otherfour species ern North America. Of states adjoining plumagefeatures, one may decisively rule out (86 cmminimum: a full 50%longer than the Wyoming,only Colorado and Utah have con- sexesand entire age classes. newspaper).All otherspecies are much larger firmed recordsfor MagnificentFrigatebird TheWyoming frigatebirdg black head rules thanLesser Frigatebird, which measures 71- (Sibley2000). Brennanand Schultz(2006) out juvenalplumage of all species,in which 81 cm (Harrison 1985). rightlyindicate that strong tropical storm ac- the head is either white or rust-colored,de- tivityis probablyonly part of theequation for pendingon thespecies. Additionally, the com- Discussion the occurrence of these birds in North Amer- binationof blackhead and white breast (Fig- Brennanand Schultz(2006) thoroughlyre- ica. While the previousMaine and subse- ure2) eliminatesmales of all ageclasses in all viewedthe only other North American record quentMichigan Lesser Frigatebirds have been species.Subadult and adult males typically ex- of this species(Maine, 3 July 1960) within assumedto bevagrants of theSouth Atlantic hibit a dark headand upperbreast. though theiraccount of theMichigan Lesser Frigate- Oceansubspecies trinitatis, which breeds on manyage classes have a whitebelly (Harrison bird. The occurrenceof any frigatebirdin severalislands far east of the coastof Brazil, 1985,Howell 1994). In Figure2, theWyoming bird showsa dark head/throat,white breast, and dark belly,defining it as a female.The rustytinge to thewhite collar, also apparent on theblack throat in Figure2, wasdetermined to be stainfrom the handlerõ leather gloves. Separationof closeage classes can be diffi- cult,as frigatebirds may take 4+ yearsto reach maturity(Harrison 1985, Howell 1994). Ex- aminauonof the wingshows a non-juvenal p10 (tenthprimary) and staffelmauserpri- mary-replacemempatterns indicative of a frigatebirdat leastfour years old (Figure1; PeterPyle, pets. comm.). [hus,this bird has reachedmaturity and can be safely considered an adult female. For adult femalefrigatebirds, the ventral patterningis crucialfor separating species. The whiteaxillary spurs (Figure 2) rule out Mag- nificentand all buta smallproportion of Great Frigatebirds(Harrison 1987). Moreover,un- Figure1. Dorsalaspe• of a LesserFflg•ebird found •ar Basin,Big Ho• County,Wyoming on11 July 2003. Note the e•ensive white like in MagnificentFrigatebird. the Wyoming hindcolor, whit•h alar bars, pink bill, and reddish o•ital ring.The rusty tinge • t• collar(s• alsoFigure 2) isresidue from the han- frigatebirdhas a reddishorbital ring, pink bill, dle•sleather •oves. Photograph by andan extensivewhite collar dorsally (Figure 1): Magnificentshows a blueorbital ring, gray- ishbill, anda reducedgray hind collar (How- ell 1994). The black throat rules out female GreatFrigatebird, which has a palegray throat; likewise, the white hind collar and alar bars (Figures 1, 3) further eliminateGreat, in whichboth arebrown (James 2004). Of the threeremaining species, Ascension and ChristmasIsland are superficiallymore similarto theWyoming bird. However, pale- morph adult femaleAscension Frigatebird has a dark head and brown chest (Harrison 1985), bill and orbitalring colorare grayish and pale blue, respectively,and Ascension also has a dark alar bar. Christmas Island Frigatebirdhas more extensive white plumage below. which connects the collar to the chest and the belly,as well as black breast-tabs (James2004): the Wyoming frigatebird's belly was black, and the white chestlacked black breast-tabs(Figure 2). Thus,we areleft only with LesserFrigatebird as having no plumage Figure2. Ventralaspect ofa LesserFrigatebird found near Basin, Big Bran County, Wyoming on11 July 2003. The prominent white characteristics inconsistent with the axillaryspurs, black belly, and whlto chest help to rule out all other frigatebird species. œhotograph bJ•Susan
VOLUME 60 (2006) NUMBER 3 329 IREASSESSMENTOFAFRIGATEBIRD RECORDFOR WYOMING
Figure3. LesserFrigatebird found near Basin, Big Horn County, Wyoming on11 July 2003, shortly before its death. This live bird is only slightly longer than a standard-sizednewspaper (56cm), a meas- urementthat places the bird's estimated length below the range of all other frigatebird species. Photographer unknown (also for frontispiece). the sourcepopulation for theWyoming Less- ment,as the species is alreadya vagrantin the graphsin thispaper and to Susan Ahalt for per- er Frigatebirdis perhapsless likely to be in northeastern North Pacific Ocean. missionto useher photographs of the bird. the Atlantic.The lack of significanttropical In the intermountain West, there is scant weatherduring the timeof the bird'sdiscov- precedentfor this record. Colorado'sonly Literature cited ery,along with the prevailingwesterly winds MagnificentFrigatebird record was of an Brennan,C., and J. Schultz. 2006. A second precedingthe date of itsdiscovery, suggest in- adult femalefound near Denveron 14 Sep- North Americanrecord for LesserFrigate- steadan lndo-Pacific Ocean origin, thus most tember1985, then again at a mountainreser- bird (Fregatamiel). NorthAmerican Birds likelyindicative of a birdof thenominate sub- voir on 16 September.The frigatebird,appar- 60: 164-165. species,which is a widespreadbreeder in the entlyin a starvedstate, was eventually killed Harrison,P 1985. Seabirds:An Identification central and eastern Indian Ocean and which bya groupof windsurfersafter it accostedone Guide.Houghton Mifflin, Boston. disperseswidely. The normaldispersal range of them (Webb 1985). This record coincided Harrison,E 1987.Seabirds of theWorld: A Pho- of LesserFrigatebird populations in thelndo- with remnants of Hurricane Elena from the tographicGuide. Princeton University PacificBasin does not extendnorth of Japan, Gulf of Mexico.The possibilitythat Atlantic Press,Princeton, New Jersey. but there are a few extralimital records for tropicalweather influenced the Wyoming Howell,S. N. G. 1994.Magnificent and Great Siberiaand Hawaii(Sibley and Clapp 1967, LesserFrigatebird• arrival in the way that Frigatebirdsin the easternPacific. Birding Harrison 1985, Pratt et al. 1987). The sub- HurricaneKatrina almost certainly did for 26: 400-415. speciesiredalei (sometimes called Mascarene Michigan'sLesser (Brennan and Schultz James,D.J. 2004. Identificationof Christmas LesserFrigatebird) of the westernIndian 2006) appearsto be remote:the only storm Island,Great, and Lesser Frigatebirds. Bird- Oceanhas a smallerpopulation that is also activityduring this period was Tropical Storm ingAsia 1: 22-38. geographicallymore remote from North Bill, whicharrived on the upperTexas Gulf Pratt. H. D., P L. Brunner, and D. G. Berrett. America;it may not be a valid subspecies coast30 June.This weak,slow-moving sys- 1987.The Birds o,[ Hawaii and the Tropical (Marchantand Higgins1990). tem movedabruptly' eastward after making Pacific.Princeton University Press, Prince- Satelliteimagery showing weather systems landfalland was not notedfor anyavian fall- ton, NewJersey. from the weekbefore the Wyomingfrigate- out (Mark Lockwood,pers. comm.). Marchant,S., and P J. Higgins.1990. Hand- bird'sarrival marks a low-pressuresystem de- book oJ Australian,New Zealand,and velopingin the northernPacific Ocean near Acknowledgments Antarctic Birds. Volume1: Ratites to Ducks, Alaska'sAleutian Islands on 5 July; this sys- I thank SteveN. G. Howell, DavidJames, and PartA: Ratiresto PetrelsOxford University tem then movedin a southeasterlydirection, PeterPyle for their expertopinions on the Press. Oxford. towardWyoming, producing thunderstorms Wyomingfrigatebirds identification. I further Sibley,E C., andR. B.Clapp. 1967. Distribution acrossMontana and Wyomingon 8 and 9 extendmy gratitude to PeterPyle for his review and dispersalof central Pacifickesser July.The system quickly moved out, and both andcomments on an early' draft that improved Frigatebirds,Frcgata m iel. Ibis 109: 328-337. 10 and 11 July were mostlyclear (UNISYS themanuscript I am also grateful to PeterGent Unisys.2006. UNISYS lmage and Map Archive. 2006). Thus,the frigatebird,if it arrivedwith andMark Lockwood for helpwith weather in-
330 NORTH AMERICAN BIRDS