Probablehybridization between ElegantTern and Sandwi ch Tern in west-central Florida: The first North Americannesting record of ElegantTern away from the PacificCoast
RichardT. Paul hybridizationamong crested terns are con- Gulls,most terns that broughtfish into the sidered in the context of this record as well. colonyfed their chicksquickly, usually Ann F.Paul withinseconds alter landing). Over the next FIELDENCOUNTER 10to 15 minutes, the Elegant Tern, the Sand- Audubonof Florida On 23 May 2002,RTP, AFP, and ABHwere wichTern, and the chickremained together censusingbreeding birds at Island3D in east- and walkedamong the otherterns as a trio 410Ware Boulevard, Suite 702 ern HillsboroughBay, Hillsborough County, (Figure4). The chickwas pale grayish above Florida. At about 0900 hours, RTP discov- andwhitish below and was very similar to Tampa,Florida 33619 eredan Elegant Tern (Sterna elegans) in incu- SandwichTern chicks in directcomparison. batingposture along the outer edgeof a We did not find theElegant Tern on 10June, colonyof RoyalTerns (S. maxima) and Sand- butit wasseen on theisland (away from the wich Terns (S. sandvicensis). As he colony)on 10 July,when it wasnot dearly BillPranty approached,the tern stood up, revealingan associatedwith anyother birds. AvianEcology Lab eggunderneath. Lacking a cameraon the boat,RTP called BP, who. along with DJP,met lDENllFlOll10N ArchboldBiological Station theothers later that morning. By the time we In directcomparison, the ElegantTern was intermediate in size between the Sandwich 123 Main Drive returnedto the island,around 1150 hours, the ElegantTern was gone and a Sandwich andRoyal Ierns. The forehead and cap were Versa,FL 33960 Ternappeared to havetaken its placein the nearlywholly black (Figures 1, 2), andthe colony.To avoid excessivedisturbance to crestwas extremely long and shaggy (Figure LaughingGulls (Larus atricilla) nesting 3). Ihe underpartswere rosy, and this color nearby,we beganto departthe island after a was so conspicuousthat it enabledus to AnnB. Hodgson fewminutes, when the Elegant Tern flew in. locatethe tern on 7 Juneas it approached BirkittEnvironmental Services, Inc. It landedin the colonyand stood about 0.6 the island.(Bright lighting conditions and m from its nest for about one minute, but distanceprevented this character from being 110S. Edison Avenue then flew down the beachand preened. visiblein our photographsand videotapes.) Videotapesand photographsof the Elegant The mantleand wingswere roughlythe Tampa,FL33606 Ternwere obtained by BPand DJP,but nest- sameshade of grayas thoseo[ the other ing wasnot documented(sensu Robertson ternsand conu•astedwith the whiterump. andWoolfenden 1992). The following morn- At rest,the primaries were blackish. The tail DavidJ. Powell ing, RTPand ABH returned to the islandat wasforked and appeared to be completely 0800 hours,and the ElegantTern was not white.The bill seemedto be longerthan the 1407Storington Avenue present.By noon,however, it had returned, lengthof the head,but the shaggycrest andRTP photographed the Elegant Tern as it madeit difficultto determinehead length Brandon,Florida 33511 incubatedits egg(Figures 1-3). precisdy.Ihe rosyunderparts, downcurved On 7 June, we revisitedthe islandand bill reddishwith a yellowishtip--nearly scanned the beach from about 15 m offshore. full blackcap, and extremdyshaggy crest ABSTRACT Dozensof tern chicks,estimated to be about indicatedan ElegantTern in definitivealter- This articlesummarizes the nestingof an one week old, lined the shoreline, most nate plumage,and bill morphologysug- ElegantTern (Sterna elegans) with a Sand- guardedby oneor twoadults. Choppy water gesteda male(Olsen and Lamson 1995). wich Tern (5. sandvicensis)on Island 3D in impairedviewing and videography,but we Weruled out other similar tern species by eastern HillsboroughBay, Hillsborough observedthe ElegantTern fly in with a fish plumage characters,apparent size, and County,Florida in a mixedcolony of Sand- andland next to a chickguarded by a Sand- apparentsize of bill. Rosyunderparts are wichTern. We did not observethe Elegant unique to ElegantTerns among orange- 2002. Worldwidevagrancy in ElegantTern, Tern feed the chick but are confident that it billed crested terns (Olsen and Lamson • wichfield separationandRoyal from(5. maxima) similar Ternsspecies, inMayand did. (Due to harassmentfrom Laughing 1995), and the bird's size--intermediate 't 280 NORTH AMERICAN BIRDS betweenRoyal and Sandwich Terns--rules outthe smaller Cayenne Tern (S. [sandvicen- sis] eurygnatha)of the WestIndies and South America,which is s•milarin size to the American race of Sandwich Tern, acu- flavida.Cayenne Tern has a straight,mostly yellowishbill, but orange-billedexamples areknown from the VirginIslands, Nether- landsAntilles, and Argentina, as well as else- wherein its range(Ansingh et al. 1960, Voous1968, Buckley and Buckley 1984, van Halewyn1985, 1987; E Hayes,pers. comm.; A. Jaramillo,pers comm.),and the sus- pectedhybridization of ElegantTern with CayenneTern in thesouthern Caribbean at Curacaohas been raised as a possiblesource of suchbirds (Ansingh et al. 1960,Shealer Figure1.Elegant Tern incubating anegg at Island 30, Hillsborough Bay,Hillsborough County, Florida, 24May 2002. 1999). ]-he smallerLesser Crested Tern (S. Island30is one of two dredged-material disposal sites for the main shipping channel through Tampa Bay to the Port bengalensis)ofthe Old World has a straight, ofTampa. Both islands areowned bythe Tampa Port Authority andare designated sanctuaries ofthe National Anduboa orange-yellowbill, and a grayrump and tail Society.Roughly 2.6km long by I kmwide, Island 30consists ofa diked area into which dredged material ispumped. (Olsen and Larsson1995). The Florida Currentshave deposited sandand shell flats up to 100 m wide outward ofthe dike in some places. One of these flats OrnithologicalSociety Records Committee supportedthebreeding colony ofRoyal and Sandwich ternsthat contained theElegant Tern. The plant visible inthe photographs isRailroad Vine (Ipomoea pes-caprae). Photograph byRichard T.Paul. (FOSRC)accepted our fieldnotes, photo- graphs,and videotapes as constituting a ver- ifiablerecord of an ElegantTern (R. Bow- man,FOSRC Secretary, in litt.).
DISCUSSION TheElegant Tern has an extremely restricted breedingrange--three coastal colonies in southern California and two in the Gulf of California,Mexico, with between90 and97 percent of theworld's population nesting at lsla Rasa,Mexico (Burnesset al. 1999, Lefevreand Burness2000). During post- breedingdispersal, Elegant Terns wander northalong the Pacificcoast regularly to northernCalifornia, and in smallernumbers to Oregon,Washington, and occasionally southern British Columbia. They winter Figure2.Begant Tern standing overits egg, Island 3D, 24 May 2002. The long, thin bill, reddish with ayellowish tip, coastallysouth to Ecuadorand Chile, prin- suggestsamale. Note the beginning ofprebasic moltof white featbering inthe forehead, which isfar more cipallyin the HumboldtCurrent region, advancedinmust of the Sandwich and, especially, Royal terns. Photograph byRichard T.Paul. with a few north as far as Mexico (A.O.U. 1998, Burnesset al. 1999). Vagrantshave Soto CountyPark, PineliasCounty 2-29 bredwith an ElegantTern in Californiain strayedto Arizona,Florida, New Mexico, December2000 (Pranty2001a; DJP,pets. 1995 and 1997 (Collins 1997), one or more Texas,Virginia, and Massachusetts,and, obs.).Presumably, this individual was relo- ElegantTerns bred with Sandwich Terns in remarkably,to Belgium,England, France, catedat thepark 20-29 April2001, when it France from 1974 to 1985 (Olsen and Lars- FrenchGuiana. Ireland, Johnston Atoll, the wasseen courting and copulatingwith a son 1995), and lone LesserCrested Terns Netherlands,and NorthernIreland (A.O.U. Sandwich Tern (L. Atherton in Pranty havebred with SandwichTerns in England 1998, Burnesset al. 1999, Kwater 2001, 200lb). Fort De Soto County Park is and the Netherlands (Olsen and Larsson Williams2001, 11iff2002, Lockwoodet al. approximately45 km southof Honeymoon 1995).The nesting of a vagrantElegant Tern 2002, Marshall 2002, Millington and Island and 35 km southwest of Island 3D. with a Sandwich Tern in Florida is therefore Gandett 2002, Ellison and Martin 2003). ThisElegant Tern record also was accepted not surprising,especially considering the Their long migration,the longestof any by theFOSRC (R. Bowman,in litt.). There presenceof ElegantTerns in thearea for the large tern in North America,probably havebeen several subsequent observations previoustwo years. Indicating the close rela- explainstheir propensity for vagrancy ol Elegantand "Elegant-type" terns in the tionshipbetween the species,Mayr and Floridagfirst Elegant Tern, a bird in sec- TampaBay area (Pranty 2002), but these Short(1970 in A.O.U. 1998) consideredEle- ond-basicplumage, spent at least two havenot yet been reviewed by theFOSRC gant,Sandwich, and Lesser Crested Terns to monthsat HoneymoonIsland State Recre- (R. Bowman,in litt.). Most of theseterns representa superspecieswith Chinese ationArea, Pinellas County 3 Octoberto 22 havebeen photographed by LynAtherton, CrestedTerns (S. bernsteini) Most reports of November1999 (Pranty 2000, Bowman and imagesare postedto her website vagrantElegant Terns have occurred within 2001,Kwater 2001). Honeymoon Island lies (). sent a genuine increasein vagrancyor northwestof Island 3D. A year later, Vagrantcrested Sterna terns breed readily merelyimproved observer coverage or iden- Florida'ssecond Elegant Tern, also in sec- withcongeners in theabsence of members tification skills is not known. Additional ond-winterplumage, appeared at Fort De of theirown species. A loneSandwich Tern researchinto vagrancyand plumagevaria-
VOLUME 57 (2003) NUMBER 2 281 can Birds 56: 37-41. Kwater,E. 2001.First record of Elegant Tern in Florida. Florida Field Naturalist 29: 90-94ß Lefevre,K., and G.E Burness.2000. A closerlook: Elegant Tern. Birding 32: 146-153. Lockwood,M. W.,G. Lasley,W. Sekula,and B. Freemanß2002 The fallmigrauon: TexasRegionß North American Birds 56: 70-74. Marshall,E 2002.Ire ElegantTern in Devon- a newBritish bird. Birding World 15: 209-211. Millington,R., andS. Gantlett.2002. The orange-billedtern in Norfolk.Birding World 15: 244-246ß Figure3. ElegantTern standing over its egg, Island 3D, 24 May 2002. Note the extrernely shaggy crest. Olsen,K.M., andH. Larsson.1995. Terns of PhotogrophbyRichnrd T.Peal. Europeand North Americaß Princeton Uni- versityPress, Princeton, New Jersey. Pranty,B. 2000. Fieldobservations fall report:August-November 1999. Florida Field Naturalist 28: 78-90. ß 2001a. Field observations winter report:December 2000-February 2001 Florida Field Naturalist 29: 100-l12. ---. 200lb. Fieldobservations spring report:March-May 2001. Florida Field Naturalist 29: 130-141. --. 2002.Field observations fall report: August-November2001. Florida Field Naturalist 30: 65-76. Robertson,W.B., Jr., and G.E. Woolfenden. 1992.Florida Bird Species: An Annotated List.Special Publication No. 6. Florida Figure4. BegantTern, Sandwich Tern, and presumed hybrid chick, estirnated at one week of age, among Royal and Sandwich OrnithologicalSociety, Gainesville, Ternsand their chicks atIsland 3D, 7 June 2002. Photograph from digitalvideotape byBfflPranty. Florida. Shealer,D. 1999. SandwichTern (Sterna tionin Cayenne,Elegant, and Lesser Crested wich Tern in Curacao in 1958. Ardea 48: sandvicensis).in The Birds of North Ternsshould refine our understandingof 51-65. America,No. 405 (A. Pooleand E Gill, "Elegant-iype"terns seen away from the Bowman,R. 200l. ]FloridaOrnithological eds.). The Birdsof North America,Inc., Pacificcoast of the Americas,of which sev- Society]Records Committee secretary• Philadelphia,Pennsylvania. eral--most recentlyin England,the Nether- reportßOnline version posted to the van Halewyn,R. 1985.Conservation lands,Massachusetts, Virginia, and Texas in FloridaOrnithological Sociciy website: programmefor CayenneIern Sterna 2001 and 2002 have alreadystimulated
282 NORTH AMERICAN BIRD