IALesser Second FrigatebirdNorth Americanfire ata Reco ariel) dfor

CALVINBRENNAN ß JEFFSCHULTZ ß SOUTHEASTERNMICHIGAN RAPTOR RESEARCH ß C/O LAKE ERIE METROPARK ß 32481 WEST JEFFERSON ß BROWNSTOWN, MICHIGAN 48183 ß BRENNANEMAIL: [email protected] ß SCHULTZ EMAIL: [email protected]

Abstract theupper end of the channel.Upon reaching curatelyby comparisonto thecormorant and This paper documentsthe occurrenceof the gulls.the frigatebirdmade a sharpdive thegulls it harassed.We judgedit therebyto LesserFrigatebird, formerly Least Frigatebird into the midstof thegroup, scattering them. havea wingspansimilar to thatof an Osprey (Fregata ariel), at Lake Erie Metropark, Fromthere, •t roseup overthe wateragain (Pandionhaliaeutus) rather than similar to or WayneCounty, Michigan on 11 September andcontinued to makepasses back and forth greaterthan that of a BaldEagle (Haliaeetus 2005. Field separationfrom other Fregata within the confines of the channel some leucocephalus).Was this bird an atypical Mag- speciesis discussed,along with noteson the 15-20 m above the surface.It eventually nificentFrigatebird, we wondered,or some- first North Americanrecord of the species, driftedfarther away from the hawkwatch site, thingmuch more extraordinary? We realized from Maine. stayingalong the extreme northeastern end of in the field that some research would be re- thechannel, and continuing on thistrack un- quiredto identifythe bird from our notesand Field Encounter til out of view of the observers. photographs(Figures 1-5). On 11 September2005, at approximately Uponfirst seeing the bird, we notedthat it 1630 EDT, a frigatebirdwas observedfor possessedthe typicalproportions of a frigate- Identification 20-25 minutes at SoutheasternMichigan bird,having the classicprofile of a largebut The relative size and proportionsof the RaptorResearch• (SMRR) principal hawk- veryslender dark seabird with long,angular, frigatebirdwere consideredproblematic for watchsite at LakeErie Metroparkin Brown- pointedwings, a deeplyforked, long tail, and a MagnificentFrigatebird by severalobservers stown,Michigan. long,slender, hooked grayish bill. It seemed and werenoted as such in the field.Magnifi- Thebird was initially seen at the mouthof reasonableto assumeit was a Magnificent centshave wingspans of about229-238 cm, Brownstown Creek, a small channel that Frigatebird(Fregata magnificens) and probably similarto or greaterthan that of a BaldEagle emptiesinto the mouthof the DetroitRiver. •ould have been recorded as such had had the (200 cm) (Sibley2000, Harrison 1985). How- At this point it wassome 150 m awayfrom bird flown off to the east over Lake Erie. For- ever, it was agreedin the field that the the hawkwatchsite. It immediatelytook an tunatel)•the prolonged, close views of thebird wingspanmore closely' matched that of Os- aerialdive at a juvenileDouble-crested Cor- permittedstudy, discussron, and photography. prey,about lO0 cm. Several of thephotographs morant (Phalacn•corax auratus) that was The bird'splumage was entirely black ex- of the bird includeRing-billed Gulls in the swimmingin the channel,which caused the ceptfor prominent band-like patches of white sameframe (Figure 5) and clearlyshow that cormorant to dive underwater.From there, on theaxillaries that extended just ontoadja- the bird, althoughobviously larger, does not thebird glided into the channel, bringing it to cent areas of the flanks. This feature was strik- dwarfthe gulls, as one would expect a Magnif- within 15 m of the observers and some 4-5 m ingat all distances,even to thenaked eye. The icentto doin directcomparison. Although the above the surface of the water. Its attention birdgdorsal surface appeared uniformly dark relativesize of a flyingbird canbe difficultto had apparentlybeen drawn to a groupof exceptfor slightwear in thegreater and me- judge(something we recognize daily in identi- Ring-billedGulls (Larusdelawarensis) that dian upperwingcoverts, which caused them fyingsometimes distant raptors), a difference was feedingon baitfishthat fishermenhad to lookjust slightlypaler than the remiges_ of ca. 40 cm (or 20%) shouldbe noticeablein dumpednear the park• boatlaunch close to The sizeof thebird couldbe judged fairly ac- thefield when a bird is seenat relativelyclose range.Moreover, the frigatebird• size and vet)- slenderbuild struck us as diminutive,in com- parisonwith other species present, in compar- isonwith specieswe seeroutinely (at diverse distancesand altitudes),and againstour ex- pectationsof, and experienceswith, Magnifi- centFrigatebird elsewhere. As is true of many bird taxa,frigatebirds (F•cgata)are more easily identified when the ageand sex of the bird are known.Ja•nes (2004)notes that plumage differences related to age/sexwithin a frigatebirdspecies are of- ten moredissimilar than they are to the cor- respondingplumages of other species.In Figure2. LesserFrigatebird at Lake Erie Metropark, Wayne orderto ageand sex a frigatebird.it is impor- Figure1. LesserFrigatebird at Lake Erie Metropark, Wayne County,Michigan, 11September 2005. The all-black head and tant to note the arrangementand placement County,Michigan, 11September 2005. In this view of the upper- breastand crisp white axillap/spur aredearly visible in this im- of whiteor paleareas in the plumageas well parts,note the absence ofa prominentalar bar. Photo9raph by age;this combination indicates anadult male Lesser Frigatebird. as the prominenceof upperwing"alar bars" PaulCypher. PhotographbyPaul Cypher. (or carpalbars)---contrastingly tawny coverts

164 NORIH AMERICAN BIRDS LESSERFRIGAIEBIRD 1

thatcross the wing diagonally from the carpal Discussion hasbeen included by theAmerican Omithol- joint to thehumorals or tarrials.In thecase of TheLesser Frigatebird at LakeErie Metropark ogists'Union (1998) and the AmericanBird- theMichigan frigatebird, we were able to rule wasundoubtedly transported there in partby ing Association(2002) on their official out immatureand femalefrigatebirds of all powerfulHurricane Katrina, the remnantsof checklistsas an adult male Lesser Frigatebird. species,as thesetypically have prominent which crossedto the southof the areajust whiteor buffareas in theirplumage and well- daysbefore. However, this only explains part Acknowledgments definedalar bars. The lackof anywhite areas of thebird's journey; its presence in theNorth We would like to thank David James and on theMichigan bird (other than the obvious Atlanticv, ould already be highlyunusual. In Louis R. Bevier for their comments on the axillaD' spurs)and the lack of any pro- thewestern Pacific Ocean basin, the species is photographsand manuscript and Paul nounced alar bar on the dorsal surface of the knownto strayquite far north,to Japan and Cypherfor rememberingto bringhis camera wingsrule out all combinationsof ageand even Siberia(Marchant and Higgins1990), to thehawkwatch that day. sexexcept adult male. but such recordsare few, and not all can be Adultmales of severalspecies o[ Fregatacan linkedto tropicalstorm activity. Literature cited be ruledout, basedon plumagecharacters. There is one previousrecord of Lesser •merlcan Birding Association.2002. ABA ChristmasIsland Frigatebird (E and•ewsi)has Frigatebirdfor North America.On 3 July Checklist.Sixth edition. American Birding fairlyprominent Mar bars and has an ovalof 1960, BertramLeadbetter of Beverly,Massa- Association,Colorado Springs, Colorado. white on the bellyin all plumages;addition- chusetts,took a 16rammotion picture of a AmericanOrnithologists' Union. 1998. The all); someadult males also possess white axd- frigatebirdat Deer Isle, HancockCounty, AmericanOrnithologists' Union Check-list q[ lap/spurs.Great Frigatebird (E minor)can be Maine. Alexander Wetmore later confirmed North American Birds_ Seventh editton. ruledout aswell: it hasprominent alar bars the frigatebirdas an adultmale Lesser by ex- American Ornithologists' Union, nevershows crisp white axillap/spurs. As far aminingspecimens at Harvard'sMuseum of Lawrence, Kansas. as is known, thereis no recordof an adult male ComparativeZoology and through frame-by- Harrison,P 1985. Seabirds:An Identification MagnificentFrigatebird with distinctaxillap/ frameanalysis of thefilm footage,from which Guide.Houghton Mifflin, Boston,Massa- spursor pronouncedalar bars,and so that severalphotographs were made of theclearest chusetts. speciesshould be ruled out on plumage;a par- frames.(These images are saidto be in the James,D.J. 2004. Identificationof Christmas tiallyleucistic adult male Magnificent probably archivesof the PeabodyEssex Museum in Island,Great, and Lesser Frigatebirds. Bird- wouldnot show such a distinctivepattern. As- Salem, Massachusetts;the archiveswere un- ingAsia1: 22-38. censionFrigatebird (E aquila)has white axil- der renovationwhen we inquiredin autumn Marchant,S., and P J. Higgins.1990. Hand- lariesat youngerstages of developmentbut 2005.) Althoughthe description(Snyder book o.[ Australian, New Zealand, and doesnot showthis trait in adultmales. Only 1961) of the frigatebirdis somewhatincom- AntarcticBirds. Volume 1: Ratiresto Ducks, adultmale Lesser Frigatebird (E ariel)has the plete-as it refersmore to a well-defined PartA: Ratiresto Petrels.Oxford University combinationof charactersshown by the white area on the side of the bird rather than Press,Oxford. Michtganfrigatebird. The wingspanof Lesser to an axillap/spur--and although the film Sibley,D. A. 2000. TheSibley Guide to Birds. Frigatebird(184 cm; Harrison 1985) also andphotographs have not been examined re- Knopf,New York. nearlymatches that of Osprey.the species we cently(and haveyet to be reviewedby the Snyder,D. E. 1961.First Record of the Least identifiedas mostclosely approximating the Maine Bird Records Committee; Louis R. Frigatebird(Fregata ariel) in NorthAmer- wingspanof theMichigan frigatebird. Bevier,pets. comm.), the Maine frigatebird ica. Auk. 78: 265.

Figure5. LesserFrigatebird atLake Erie Metropark, Wayne County, Michigan,11September 2005. At times, observers hadthe oppor- tunityto compare the frigateUrd with other species. It was dearly largerthan Ring-billed Gulls it harassed, butit didnot dwarf them. Figure3. LesserFrigatebird at Lake Erie Metropark, Wayne Figure4. LesserFrigatebird at LakeErie Metropark, Thefact that the gull dosest to the frigatebird isin focus in this County,Michigan, 11September 2005. Another view of ventral WayneCounty, Michigan, 115eptember 2005. Photograph photographmdlcates that their sizes relative toone another are andcephalic features. Photograph byPaul Cypher. byPaul Cypher. actualrather than artefactual. Photograph byPaulCypher.

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