RARE OCCURRENCE

The Western Reef-Heron (Eretta u/ar/s) at Nantucket Island, Massachusetts

Four thousandmiles from the nearestpoint in its normal range, this waif adds a new speciesto the WesternHemisphere list

Robert Cardillo, Alpc Forbe?Watson, and Robert Ridgely

IDENTIFICATION not have contrastingyellow toes.) "WHITE-THROATEDLittleBlue Heron" In a North American context, hitherto wasfirst noted by Edithand Clinton Andrews on Nantucket Island, Massa- EVERALSPECIES of medium-sized her- it hasonly been necessary to considerthe onsin the genusEgretta haveyellow threeegrets in group2. The Snowy is chusetts,on April 24, 1983with a "real" toes contrastingwith the darker tarsi. well known,but the other specieshave Little Blue Heron Egretta caerulea. For more than a month it was believed to be They fall naturallyinto threegroups: beenrecorded as accidentals.They are I. The Black Heron, E. ardesiaca, invariablysnowy white in plumage(the onlya sub-adultpied Little Blue. But on of Africa and Madagascar. June 7 the Andrews noticed that the heron Little hasa very rare dark morphin Eu- 2. Three egrets, the Snowy, E. rope). All three reef-heronshave dark hadyellow toes.On June22 and 25, at thula, of the New World; the Little, E. andwhite morphs like ReddishEgrets, E. EdithAndrews' request, Cardillo photo- garzetta,of muchof the Old World;the rufescens(and intermediate gray, laven- graphedthe bird. A few dayslater, after Chinese,E. eulophotes,of Asia. deror speckled).In West Africa the dark hearing Cardillo's verbal description, 3. The WesternReef-Heron, E. gu- is by far the commoner:only 2-3 white Ridgely first suggestedthat the bird !aris, of coastal Africa and the Middle phasewere found in a colony of 900 might be a Western Reef-Heron. The East to India; and the Dimorphic Egret, (Brown eta!., 1982). The occurrenceof a transparencieswere examined at the E. dimorpha,of Madagascarand Aida- dark egret-sizedheron with yellow toes Academyof NaturalSciences, Philadel- bra. These are often consideredconspe- on Nantucket Island was, therefore, of phia, and the identificationwas con- cific but it seems best to treat them as considerableinterest. Hybrids between firreedon July 11. Forbes-Watsonand separatespecies as does Peters0979). Snowy Egrets and Little Blue Herons Michel Kleinbaum (both of whom were (The EasternReef-Heron, E. sacra, does have been recorded(Palmer 1962), so it familiarwith the speciesin Africa) went to seethe bird on July 13-16 and con- firmed the identification. Thebird's dark plumage, white throat, and colorsof the bare partsare diagnos- tic, andthe moresubjective characters of the bill's heavinessand curved appear- ance served as clinchers (for details see below). At this writing (September1, 1983) the bird hasbeen seen on virtually every day sincethe first sighting.Only infre- quentlyhas it beenseen beyond the im- mediatevicinity of the Spartina marsh nearQuaise where the University of Mas- sachusetts has a field station, It occasion- ally visitsthe nearby sandy beach where, to thosefamiliar with it in Africa, it looks muchmore "in place." It will be inter- estingto seewhat its responsewill be whenwinter approachesand the Snowy Egrets,with which it consorts,depart. It haseven been suggested that it might be trappedand returned to Africa. Fig. 1. WesternReef Heron, Nantucket,MA, summer1983. Drawing/MichelKleinbaum.

Vol. 37, Number 5 827 wasat firstthought that this bird mightbe sucha hybrid. We have not been able to locate an actual descriptionof a Little Blue x Snowyhybrid, but nonethelessare con- wnced that the Nantucket Island bird is in factnot of hybridorigin. Its bill is consid- erably heavierthan a Little Blue's, not slighteras would have been expected in a hybridbetween that speciesand the slen- der-billedSnowy. Furthermore,there is no indicationof any lossof the yellow colorson the toes:if anythingthe yellow "slippers"of theNantucket Island bird are even more conspicuousthan on a Snowy, a situationperhaps enhanced by thebird's dark overallplumage. As noted above,all the morphologicalcharacters of the bird are consistentwith it beingE. gularis,as is its very active(some would call it "dashing") foraging behavior, quite unlike the relatively sedateLittle Blue and more animated even than our gracefulSnowy.

DISTRIBUTION

HEWESTERN REEF-HERON. ashere recog- Fig. 2. WesternReef Heron. Nantucket,MA. summer 1983. Photo/Robert Cardillo. Note bill. nized,is splitinto two subspecies:E. throat, color of legsand feet. g gulari$, of coastalWest Africa and E. g schistacea,of the coastsof the Red non-breedingplumage (also evidenced Behavioralnotes. Although it roosted Sea and northwestern Indian Ocean. Al- by itslacking the two nuchalplumes car- with the Snowy Egretsat night it was though normally sedentary,occasional ried in breedingplumage). Throat pure very aggressivetowards them on the individualshave been recordedin Spain white with a very narrow dirty-white marshand was often seen flying for andthe Azores (Cramp et al., 1977). It is bandacross base of uppermandible. In •< 300 yards to join groups of •< 10 pure speculationhow the NantucketIs- flight, in good light, the primaries Snowies. At the time of our observation land bird crossedthe Atlantic, but it is showeda narrowpale strip on the wing's itsdaily patternwas asfollows: at dawnit conceivable that it could have flown un- trailingedge, sometimes giving a distinct flew from the nearbyroost to the western aided, perhapswith a stop-overin the white edgeto closedwing. Legs black- edgeof the marsh,sometimes tolerating Azores. The distance from the nearest ish, toesbright yellow. A white bandon Snowieswhile preening.When the ex- population in Mauritania is c. 4000 the barepart of the tibia was sometimes ceptionallyhigh tidesof the time had re- miles, with the Azores c. 4200 miles en seen;it wasundoubtedly dried salt from cededa bit it wouldfly to the plateauof route. It may havebeen carried by strong the seawater. Bill mostly dull horn belly-high Spartina in shallow water winds and, as reef-herons are known to (greyerin somelights), upper part of cul- Here it would very actively pursuein- perchon boats(Brown et al., 1982) it menblacker, tip whitish.Bare lores and sects(including dragonflies) and small may have restedfor at least part of the orbitdull pale cream with greenishcast in fish c. 1-1V2 inches long. It was seento crossingon a ship. somelights. Iris paledull whitishcream. catchsix fish in a minute, includingtwo Bill seemsheavier, longer and more with one snap-- they were held cross- Description of Nantucket Island "droopy" than nearby Snowies', the wise in the mandibles and then were bird (in perfectfrontal lighting, observed droopbeing due to the more strongly gulpeddown. This feedingfrenzy would with a 3V2inch Questar,a 30 x scope archedculmen and "countershading" of lastuntil the plateauwas dry, whenthe and 7 x 50 binoculars from field notes the bill. Some experiencedobservers heronwould fish the open water of the by AF-W and MK, July 14-16, 1983): even thoughtthe bill was curvedup- leads and channels of the marsh. Its feed- Generalcolor uniform dark slate, in some wards! But this illusion occurred when ingpace would then generally be slower, lightswith brown or purplishcast. When thebill wasglistening wet in strongover- althoughbursts of franticactivity some- preeningor windblownshowed whitish head sunlight-- then the upper part times occurred.The posturehere was basesto body feathersand someon rear mergedwith the backgroundwhile the horizontal(similar to the positionoften flanks show most of time. Some lanceo- lower was in harsh shadow. adoptedby the Green Heron, Butortdes late feathers on base of fore-neck, and The bird showedstrong wing-molt in striatus), sometimeswith deliberatefoot- someinconspicuous filamentous plumes mid-July,but Cardillo'spictures show stirringof the bottom. The wings were from abouthalfway down back. These that at the end of Junethe hind wing- sometimesheld half-outfrom the body plumesindicate that the bird is an adultin marginwas perfect. (in a so-called"canopy," althoughthis

828 AmericanBirds, September-October1983 cordingthe first visit of thisspecies to the New World. We thank Michel Klein- baumfor his great help in thefield and for his accuratedrawing of the bird. F.B. Gill andJ.P. Myers madevaluable sug- gestionson a draftof thismanuscript.

BIBLIOGRAPHY

BENT, A.C. 1963 Life histories of North AmericanMarsh Birds:Dover reprint. BROWN, L.H., E.K. URBAN and K. NEW- MAN, 1982 The birds of Africa. volume l: Academic Press CRAMP, S. and K.E.L. SIMMONS (eds.) 1977. The birds of the Western Palearctic. Vol. 1: Oxford University Press ETCHECOPAR,R.D. andF. HU•. 1964Les Fig. 3. WesternReef Heron, Nantucket,MA, summer 1983. Photo/Robert Cardillo. Oiseauxde Nord de l'Afrique:N. Boubee and Co. HANCOCK, J. and H. ELLIOTT. 1978. The neverapproached the perfect "umbrel- afield. Anothergood example: the Varia- heronsof the world: Harper and Row, la" of a feedingBlack Heron). Edith An- gatedFlycatcher, Empidonomus varius, New York. HEINZEL, H., R. FITTER and J. PARS- drewsmade the observationthat canopy in Maine. (Abbot and Finch AB 32:161) LOW. 1972 The birds of Britain and Eu- 4. A reef-heron in the Bahamas? P. feedingwas more often seenwhen the rope:Collins sunwas directly overhead, suggesting it Bergey(in !itt. to R. Arbib) describeda KING, B., M. WOODCOCK and E.C. wasshading the watersurface for better bird she saw on Grand Bahama on No- DICKINSON 1975. A field guideto the visibility. It occasionallyflicked one vember16, 1965. It was"shiny black all birds of South-East Asia: Collins wing out, presumablyfor balance.Just over with a yellow eye and as I recall, MACKWORTH-PRAED, C.W. and C.H.B. beforealighting and also when displacing yellow legs." Without a more detailed GRANT, 1970. Birdsof West Centraland WesternAfrica. Vol. 1: Longmans,Lon- theSnowies it wouldgive a doublecom- descriptionit seemsbest to regardthis as don. plaining "aarerr" call. The bird was a very hypotheticalsighting. PALMER, R.S. (ed.) 1962. Handbook of tamer than the Snowies; this is also true 5. Edith Andrewshas promised to North American birds: Yale University in West Africa where it is often in close publisha completehistory of "reefer" Press, New Haven. association with native fishermen who do eventssubsequent to July 1983. PETERS,J.P. 1979. (E. Mayr andG.W. Cot- not normallymolest it. trell, eds.)Check List of birdsof the word Vol. I (2rid edition): Museum of Com- parativeZoology, Cambridge. Issues raised. These main points ACKNOWLEDGMENTS SERLE, W., G.J. MOREL and W. should be noted: HARTWIG 1977. A field guide to the 1. The importanceof photographs The staff of the Universityof Massa- birds of West Africa: Collins in verifying extraordinarysightings. chusettsField Station (Director W.N. SNOW, D.W. (ed.) 1978 An atlas of speci- Thesepictures are deposited with VIREO Tiffhey)are to be thankedespecially for ation:African non-passerine birds: British (Visual Resourcesfor Ornithology)and allowinga dailyintrusion into their priva- Museum(Natural History), London. TERRES, J.K. 1980. The AudubonSociety available for future consultation. cy by, to date (Septemberl, 1983) c. encyclopediaof North Americanbirds: 2000 birdwatchers. The birdwatchers 2. The importanceof following-up Knopf, New York. suchsightings, particularly when they mustbe thankedfor respectingthe privi- and the variousNorth Americanfield guides. aremade by observersknown to be reli- legesaccorded them. Without Edith and able. ClintonAndrews' original interest in the --Visual Resourcesfor Ornithology, 3. The necessaryparochialism of bird andtheir persistence in gettingit ex- Academyof Natural Sciences, regionalguides should not inhibit our amined,it maynever have been correctly 19th and BenjaminFranklin Parkway, searchingfor possibilitiesfrom farther identified. To them lies the credit for re- Philadelphia,PA 19103.

Vol. 37, Number5 829