Glossy Ibis Records for Colorado and Neighboring States

GLOSSY IBIS RECORDS FOR COLORADO AND NEIGHBORING STATES

DOUG FAULKNER,Rocky Mountain Bird Observatory,14500 Lark BuntingLane, Brighton,Colorado 80603

ABSTRACT:The GlossyIbis (Plegadis falcinellus) first arrived in the New World in the early 1800s. Duringthe twentiethcentury, this species expanded its breeding range rapidly,extending as far west as Louisiana.Vagrants have occurredthrough- out the Great Plainsand even to California.Colorado's 35 documentedGlossy Ibis through2002 aremore than in anyneighboring state by at least40%. Theserecords representprimarily single birds during spring migration; however, recent records in- cludesome of multiplebirds, as well as one in fall.Timing of theserecords, the birds' associationwith flocksof the White-facedIbis (P. chihi), and lackof nestingsites in Coloradosuggest that the GlossyIbis is continuingits migrationoutside of Colorado. The increasednumber of records,increased number of birdsper record,and recent reportsof potentialhybrids in Oklahomaand Coloradoalso suggest that the Glossy Ibismay be expandingits breedingrange west into the Great Plains.

The GlossyIbis (Plegadis falcinellus) is a cosmopolitanspecies native to the Old Worldfrom southeasternEurope to Australia.It probablycolonized North Americain the early 1800s, with the firstrecord from New Jerseyin 1817 (Baynard1913). Duringthe early 1900s, the GlossyIbis was known to nestin the UnitedStates only in Florida(Bent 1926). Nestingrecords from otherstates followed, and by the early 1960s the GlossyIbis bred along the eastcoast as far north as New York (Davisand Kricher2000). Currently,the GlossyIbis resides permanently along the Gulf coastfrom easternLouisiana to Floridaand north along the Atlanticseaboard to North Carolina(Davis and Kricher2000). Its breedingrange extends still farther north alongthe Atlantic coast to southwestern Maine. Members of the order Ciconiiformes(storks and allies)are well-knownas wanderersboth beforeand after the breedingseason. The GlossyIbis is no exception.In spiteof this species'rather limited and coastalNorth Ameri- can range, the GlossyIbis wanders regularly throughout the easternUnited States,with somerecent field guides showing a distributionfrom east-central Texasnorth to Wisconsinand eastto Newfoundland(Sibley 2000, National GeographicSociety 2002). Through2002, Coloradohad 31 recordsof 35 individualsof the Glossy Ibis.Most of theserecords pertain to singlealternate-plumaged adults found duringspring migration. This paper examines the patternof vagrancy(dates and locations)of the GlossyIbis in Colorado,with referenceto neighboring states,probes into possibleexplanations for thispattern, and notes possible hybridsin Colorado.Identification of the Glossyand White-facedIbises (P. chihi) has been treatedwell elsewhereand is not repeatedhere (seePratt 1976, Kaufman 1990, Patten and Lasley2000). For consistency,I use seasonaldefinitions established by many nationaland stateornithological publications:spring (March-May), summer (June-July), and fall (August-No- vember)(e.g., North American Birds, ColoradoBirds). Additionally, unless otherwisenoted, I useonly recordsaccepted by the respectivebird records committee for each state.

Western Birds 35:147-155, 2004 147 GLOSSY IBIS RECORDS FOR COLORADO AND NEIGHBORING STATES

STATUS IN COLORADO

Historicalsightings are oftendifficult to evaluate.A previouslack of under- standingabout the characteristicsdistinguishing the Glossyand White-faced Ibisescomplicated identification issues. Robbins et al. (1966) illustratedthe GlossyIbis with white facial leatheringextending around reddish eyes, as in the White-facedIbis. Therefore, recordsprior to the mid-1970s, when detailson Plegadisibis identification were first available to thegeneral birding public(Pratt 1976), are bestconsidered suspect, except those supported by photographicevidence, excellent written details,or extant specimens. I foundseven published reports of the GlossyIbis for Coloradoprior to the firstaccepted state record in 1986 (Baileyand Niedrach 1965, ColoradoBird RecordCommittee [CBRC] files and referencestherein). Cooke (1900) pub- lishedthe first(date unknown) and second(4 April 1898). Presumably,the firstsupposed occurrence was between1897 and 1900, as Cooke (1897) did not mentionthe GlossyIbis in thisprevious book on Coloradobirds. Severalspecimens taken in Coloradoin the early 1900s were reportedas the GlossyIbis. Niedrachand Rockwell(1959) mentionedtwo specimens, althoughneither was availableto them for examination.One apparently"in fullplumage" was collected by W. W. Cooke(1900), andthe otherwas taken in June 1905 at Barr Lake, AdamsCounty. An extant specimen(Denver Museumof Nature and Science39079) collectedon 22 May 1916 and identifiedby H. C. Oberholserwas reidentifiedin the mid-1980s by Mark Holmgrenand Joe Strunchas a White-facedIbis (CBRC files). I found no mentionof the GlossyIbis in the Coloradoliterature again until the 1950s, when 15 were reported;however, several descriptions of thesementioned the definingcharacter as the "lackof white at point of bill attachment"or "no whiteapparent on face"(Thatcher 1955, 1957, Bailey and Niedrach 1965). The latter feature characterizesseveral plumages of the White-facedIbis and was one of the reasonsfor not acceptinga 1985 Coloradoreport (Gent 1986). The firstColorado bird listpublished by the ColoradoField Ornithologists includedthe GlossyIbis because of the extantspecimen previously mentioned (Reddal11973).After the specimenwas reidentified, however, a laterCBRC report removedthe speciesfrom the statelist (Gent 1987). The firstrecog- nizedColorado record was of a birdfound in the westernpart of the stateat SweitzerLake StatePark, Delta County,27 March 1986, associatingwith a flockof White-facedIbises (Bunn 1988). This recordwas basedon excellent written descriptionsby two observersas well as a sketch. After 1986, therewere only three additional records until 1995, andnone from 1991 to 1994 (Figure 1). Since 1995, the GlossyIbis has occurred annually,with mostrecords (28 of 35; 80%) comingfrom two areaseast of the continentaldivide: the ArkansasRiver valley and the northernFront Range(Figure 2). In mostcases, records pertain to singlealternate-plumaged adultsin springassociated with flocksof White-facedIbis. Thirty-three of the 35 individuals(94%) occurredbetween 27 Marchand 31 May, and 27 of the 35 (77%) occurredbetween 16 April and 15 May (Figure3). Multiple birds have been encountered since 2000: two records, one each in 2000 and 2001, are of two GlossyIbises observed together, and a thirdrecord in

148 GLOSSY IBIS RECORDS FOR COLORADO AND NEIGHBORING STATES

14 12

ol I I I ,

Figure1. Yearlyoccurrence and numberof individualsof the GlossyIbis in Colorado (black)and neighboringstates (gray).

2002 is of threebirds together. Outside of springmigration, Colorado has a singlesummer record, 4 July 1990, from HuerfanoCounty, and a singlefall recordof a bird stillin alternateplumage photographed at Loloff Reservoir, Weld County, 27 August2002 (Leukeringand Semo 2004). Recentobservations have suggestedhybridization between the Glossy andWhite-faced Ibises in North America(Arterburn and Grzybowski2003). Possibleinterspecific hybrids have also been observed in Colorado.In May 2002, a possiblehybrid was photographedin BroomfieldCounty (Wood and Semo 2002). Another individualexhibiting hybrid characteristics was photographedin El Paso County,July 2003 (pers.obs. of photos).Both reports,however, have yet to be submittedto the CBRC.

STATUS IN NEARBY STATES

A specimenwas obtainedin Oklahomain 1954 (Sutton1955). Among Colorado'sneighboring states, that specimenremained the region'sonly confirmedGlossy Ibis until 1991, when the secondwas documentedfor Oklahoma.Kansas quickly followed Oklahoma's second with its first state record in 1992, but it was not until 1999 that Nebraskarecorded its first GlossyIbis (Sharpeet al. 2001). From 1946 to 1964, however,Nebraska birdershad reported 10 GlossyIbises, although none of themwas sufficiently documented(Sharpe et al. 2001). Since 1999, at leastone GlossyIbis has been recordedannually for Kansasand Oklahoma.Except for two records from Coloradoand one from New Mexico,all of the region'ssummer and fall records come from these three states.

149 GLOSSY IBIS RECORDS FOR COLORADO AND NEIGHBORING STATES

Figure2. Distributionof GlossyIbis records in Coloradothrough 2002.

Of the statesnorth or westof Colorado(Montana, Wyoming, and Utah) only Wyominghas any acceptedGlossy Ibis records.Wyoming's first was of an adultobserved near OceanLake 5 May 1992 (Luceet al. 1997). The state'ssecond occurred in 1999, when an adultwas found near Jackson4 May (Truanand Percival1999). Both of theserecords are from the western half of the state.In 2002, fourbirds were reportedfrom Wyoming,all still underreview by the WyomingBird RecordsCommittee. I observedone of these,an adultin definitivealternate plumage near Cheyenne5 May. Two weekslater, on 18 May, two alternate-plumagedadults were alsoseen near Cheyenneby experiencedobservers Steve Dinsmore, Jr., andJoe Fontaine. The last sightingwas of an adultnear Dubois,in the westernhalf of the state(Wyoming Bird Records Committee files). Montana lists the GlossyIbis as hypotheticalon the basisof a convincingreport of an adulton 24 May 2002 near Choteau,Teton County(Lenard et al. 2003). Arizona and New Mexico both have GlossyIbis records,with Arizona's solerecord in May 2001 (Rosenbergand Jones2001). New Mexico'sfirst recordcame in 1995, followedby threein 1999 and fivein 2001, the last includingthe state'sfirst fall record,of a singlebird photographedin Sep- tember.Four more individualswere recordedin 2002, includingtwo birds togetherat LasVegas National Wildlife Refuge on 5 May (New MexicoBird RecordsCommittee files).

150 GLOSSY IBIS RECORDS FOR COLORADO AND NEIGHBORING STATES

18--

Figure 3. Seasonaldistribution of GlossyIbis recordsin Colorado (black)and neighboringstates (gray) through 2002.

DISCUSSION

The concentrationof Colorado'sGlossy Ibis records in springis not sur- prising.All recordsthrough 2002 are of adultbirds in definitivealternate plumage(CBRC files).Adult Plegadisibises differ most in this plumage, worn in spring,so a Glossyis more likelyto be pickedout of a flockof the White-facedat thistime of year.The periodof concentrationof GlossyIbis records,16 April to 15 May (Figure3), coincideswith the peakmigration period of the White-facedIbis in Colorado(Andrews and Righter 1992). A potentialsource of biascontributing to this concentrationof recordsis increasedbirder activity.If this factor is significant,however, then birders are under-reportingthe GlossyIbis in Coloradoin summerand fall when it is difficultto distinguishfrom the White-facedIbis. Recordsfrom adjacentstates, primarily Kansas, Nebraska, New Mexico, andOklahoma, also follow this general pattern (Figure 3), peakingsharply from 16 April to 15 May. A smallerpeak occurs in July(10 records).Re- cordsoutside of the springperiod (June-October) are dominatedby Kansas and Oklahoma,encompassing 17 of 22 individuals(77%), and thusare not representativeof the region as a whole. These summerand fall records probablyrefer to postbreedingwanderers. Kansas and Oklahomaare more likelyto receivepostbreeding wanderers because those states are nearerto the GlossyIbis's known breeding locations than the other statesaddressed in this paper.

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All but four of Colorado's35 GlossyIbis records in Coloradoare are for 1995 and later. The pattern in neighboringstates, especially Kansas, is similar.Of the 15 GlossyIbises reported in Kansasthrough 2002, all butone haveoccurred since 1995, with only 1998 lackinga record.Since 1999, the GlossyIbis has been reportedannually in Nebraska,New Mexico,and Oklahoma,in some casesas multipleindividuals. In these statesthe lag between1995 and the upsurseof reportsin 1999 may havebeen due only to a lag in birders'vigilance for this easilyoverlooked species. The concentrationof GlossyIbis records in Coloradorelative to neighboring statesis mostlikely due to the concentrationof birdersalong the heavily urbanizedbase of Colorado'sFront Range.This area also featuresmany reservoirsand wetlands used by the White-facedIbis during migration. Also, the ArkansasRiver valleyfrom Puebloeast to the Kansasborder is visited nearly daily by birdersfrom late April to mid-May (pers. obs.).Themajor wetlandswhere the White-facedIbis occurs in Kansas(e.g., QuiviraNational WildlifeRefuge), Oklahoma (Salt Plains National Wildlife Refuge), and Ne- braska(Valentine National Wildlife Refuge)are in the central or western portionsof thesestates where the humanpopulation is low. The contrastin numberof GlossyIbis records between eastern Colorado and regionswest of the continentaldivide may be relatedto where White- faced Ibis populationswinter. Bandingstudies in the 1960s suggestthat White-facedIbises breeding in Utah andother states west of the dividewinter in westernMexico, outside the winter rangeof the GlossyIbis. Ibises breeding eastof the dividewinter along the northernshore of the Gulfof Mexico (Ryder1967). ThereforeGlossy Ibises wandering from the southeasternU.S. aremore likely to joinflocks of theWhite-faced Ibis of the easternpopulation andaccompany them north, provided that these flocks remain intact through springmigration and do not crossthe continentaldivide. The few Glossy Ibisesrecorded in California, Arizona, and western Mexico (seePatten and Lasley2000) mayhave joined flocks of the White-facedwintering in western Mexico,then migratednorth with them to far westernstates. Might the greater concentrationof GlossyIbis recordsin Coloradobe due to the ColoradoBird RecordsCommittee having a lower standardfor acceptanceof theserecords than other staterecords committees? I discount thishypothesis because all of Colorado'sGlossy Ibises records are of birdsin definitivealternate plumage. In reviewingthe recordsI foundthat observers consistentlymentioned the species'salient characteristics: blue facial skin, dark eyes, reducedwhite border on facial skin, and red tarsusjoints with otherwisedark legs.Some recordsinclude diagnostic photographs as well. The documentationis adequateto excludethe possibilityof hybrids,which are more likelyin areaswhere the breedingranges of the White-facedand Glossyoverlap than in Colorado.Reports of possiblehybrids in Colorado in 2002 and 2003, however,do raisethe bar for futureGlossy Ibis docu- mentations.

BREEDING AND HYBRIDIZATION

The final destinationfor the GlossyIbises occurring in Coloradois unknown.There is only one knownnesting location for the White-facedIbis

152 GLOSSY IBIS RECORDS FOR COLORADO AND NEIGHBORING STATES in easternColorado, the privatelyowned Lower Latham Reservoirin Weld County.Because the site is birdedheavily it is doubtfulthat GlossyIbises summer there. Each summer,the Rocky Mountain Bird Observatorysurveys all acces- siblewetlands in Coloradoas part of large-scalebreeding-bird monitoring (Leukeringet al. 2000). It is doubtfulthat ibisescould nest anywhere in easternColorado without the sitebeing documented at leastonce in the past fiveyears of thisprogram. Furthermore, the recentmulti-year drought has severelyreduced the numberof wetlandson the easternplains suitable for waterbirdnesting (pers. obs.). Therefore, because the GlossyIbis is recorded predominantlyin eastern Colorado, especiallyalong the northern Front Range (Adams,Boulder, Larimer, and Weld counties),the speciesis likely continuingits migrationwith White-facedIbises to breedingareas farther north. The increasein reportsfor Wyoming,especially in 2002, provides somesupport for this idea, thoughMontana has only one convincingsight- ing. Thesestates' low densityof humanpopulation, hence of birders,may be responsiblefor this dearth of records. The GlossyIbis is not knownto nestin Coloradoor in neighboringstates, thoughit may.In a wetlandin south-centralNebraska an apparentpair of the Glossywas found in summer2001 aftera nearbycolony of the White-faced Ibis was abandoned(Dinsmore 2001). Also, in summer 2002, four adult GlossyIbises were at Salt PlainsNational Wildlife Refuge, Oklahoma, in a recentlyestablished breeding colony of the White-faced(Grzybowski 2002). The Glossyis also becomingregular in Kansasin summerat Quivira Na- tionalWildlife Refuge and CheyenneBottoms, sites of 13 of that state's15 records,although it is possiblethese birds were postbreedingwanderers. No breedingwas documentedby the KansasBreeding Bird Atlas (Busby and Zimmerman 2001). Observationsof apparentGlossy x White-facedIbis hybrids in the United Statesare recent,although these species have interbred freely at the London Zoo (Gray 1958, Palmer1962). Up to fiveapparent hybrids were discov- ered in Oklahomaat Salt PlainsNational Wildlife Refuge in summer2002 (Arterburnand Grzybowski2003). Two have been reported in Colorado (seeunder Statusin Colorado).The sourceof these potentialhybrids is unknown.They may originatefrom farther east where the White-faced and Glossyoverlap or be the resultof mixed pairingsin the Great Plainsat unknown locations. Sincethe firstaccepted state record in 1986, the GlossyIbis has become a regular,if rare, springmigrant in Colorado.The species'increase in the regionsuggests that it may be expandingits nestingrange further. Glossy Ibisnesting should be lookedfor throughoutthe Great Plains,particularly during the late spring and summer,at known nesting locationsfor the White-faced Ibis.

ACKNOWLEDGMENTS

! thank Peter Gent, Tony Leukering,Larry Semo, and ChrisWood for reviewing earlierversions of this paper. Jim Arterburn(Oklahoma), John Carlson(Montana), AndreaCerovski (Wyoming), Joseph Grzybowski (Oklahoma), Jeff Marks(Montana), ChuckOtte (Oklahoma),Susan Patla (Wyoming), David Rintoul (Kansas), Ross Silcock

153 GLOSSY IBIS RECORDS FOR COLORADO AND NEIGHBORING STATES

(Nebraska),and Sartor O. Williams,III (New Mexico),provided records of statecom- mitteesor otherinformation pertaining to GlossyIbis occurrences in their respective states.My appreciationto MeganMcLachlan of RockyMountain Bird Observatory for creatingthe map in GIS. I thank MichaelA. Patten, Dan Reinking,and two anonymousreviewers for their comments.

LITERATURE CITED

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Niedrach,R. J., and Rockwell,R. B. 1959. Birds of Denver and Mountain Parks, 2nd ed. Denver Mus. Nat. Hist., Denver. Palmer, R. S., ed. 1962. Handbook of North American Birds, vol. 1. Yale Univ. Press, New Haven, CT. Patten,M. A., and Lasley,G. W. 2000. Rangeexpansion of the GlossyIbis in North America. N. Am. Birds 54:241-247. Pratt, H. D. 1976. Field identificationof White-facedand GlossyIbises. Birding 8:1-5. Reddall,J. 1973. Officialstate list of the birdsof Coloradoas of June 1, 1973. Colo. Field Ornithol. J. 17:3-14. Robbins,C. S., Bruun, B., and Zim, H. S. 1966. Birdsof North America.Golden Press,New York. Rosenberg,G. H., andJones, R. M. 2001. Arizona.N. Am. Birds55:332-335. Ryder, R. A. 1967. Distribution,migration, and mortalityof the White-facedIbis (Plegaclischihi) in North America.Bird-Banding 38:257-277. Sharpe,R. S., Silcock,W. R., andJorgensen, J. G. 2001. Birdsof Nebraska.Univ. Nebr. Press, Lincoln. Sibley,D. A. 2000. The SibleyGuide to Birds.Knopf, New York. Sutton,G. M. 1955. GlossyIbis ir• Oklahoma.Condor 57:119-120. Thatcher,D. M. 1955. Birdsof the month. Colo. Bird Notes 2(9):5-7. Thatcher,D. M. 1957. Birdsof the season.Colo. Bird Notes 4:72-74. Truan, V. A., and Percival, B. K. 1999. Mountain West region. N. Am. Birds 53:306-308. Wood, C. L., and Semo, L. S. 2002. News from the field:The spring2002 report (March-May).J. Colo. FieldOrnithol. 36:200-228.

Accepted 16 June 2004

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