NOTES

LEUCISTIC BLACK-VENTED (PUFFINUS OPISTHOMELAS) IN SOUTHERN CALIFORNIA

KIMBALL L. GARRETT, Section of Ornithology, Natural History Museum of Los AngelesCounty, 900 ExpositionBlvd., Los Angeles,California 90007

In his account of the biology of the Black-vented (Puffinus opisthomelas),Everett (1988) mentionedthat "leucismand partialalbinism... are so far unrecordedfor opisthomelas."Such plumageaberrations are widely recorded among , including,among procellariids,Sooty Shearwaters(?. griseus•Palmer 1962, Stallcup1976) and a GreaterShearwater (P. gravis)off New England(Vickery 1978). Within the Puffinuspuffinis complex, leucismhas been documentedfor ?. p. mauretanicus(Mackrill and Yesou 1988, Elkins 1990) and P. p. puffinus (Fluram 1990). This note presentsphotographic documentation of two leucisticBlack-vented Shearwatersand brieflydiscusses implications for field identificationof shearwaters. Leucism is used here in the sense of Buckley (1982) to signifya reduction or local absenceof pigmentshort of albinism(the completelack of pigment). On 14 January 1984 Arthur L. Howe observedand photographedan odd shear- water from the vessel$/•arps/•ooter in Santa Monica Bay, Los AngelesCo., Califor- nia. Becausethe was with a large group of Black-ventedShearwaters and iden- tical to them in size, shape, and style of flightyhe tentativelyidentified the bird as a Black-ventedShearwater. The one photographhe obtained(Figure 1) confirmsthis identification. In the field the bird showed diluted pigmentationon the head and neck, being essentiallywhite-headed with a pale browncrown and pale brownand white mottling on the hindneck. The Black-vented Shearwater's crown color is normally "dark brown" (Palmer 1962, Harrison 1983). The white of the face, throat, and auricular area extended well back to the sidesof the neck. The general dorsalplumage color was that of typical ?. opistl•omelas,though somewhatpaler; the extent to which plumagewear mighthave contributedto the paler dotsumis uncertain.The undertail covertsappeared dusky, as is typicalof this .Another opist•omelasin similar plumagewas observedin Santa Monica Bay in January 1988 (Howe pers. comm.). On 7 March 1987 Jonathan K. Alderlet observedand photographeda Black- vented Shearwaterin the San Pedro Channel, Los AngelesCo., with extensivewhite in the primaries, secondaries,uppertail coverts, undertail coverts, and hindneck (Figures2-4). This individualalso showed white mottlingon the crown. Like the bird photographedby Howe, thisbird wasobserved with normallyplumaged Black-vented Shearwatersand was identicalin sizeand shape (Figure4). The extensivewhite in the wingswas very evidentin flight (Figures2-3). An apparent?. opis•homelasshowing large white wing patcheswas noted by Howe (pets. comm.) in Santa Monica Bay in November1988; it was not photographed. Leucismand other plumage anomaliesin seabirdshave obviousimplications for field identificationsince species diagnosis at sea reliesheavily on generalplumage pat- tern and coloration(along with flightstyle and shape)rather than the detailsof struc- ture and plumage. Leucismin Sooty Shearwatershas likelygiven riseto some claims Western Birds 21:69-72, 1990 69 NOTES

Figure 1. LeucisticBlack-vented Shearwater in Santa Monica Bay, Los Angeles County, California, on 14 January 1984. Photo by Arthur L. Howe

Figure 2. Boldly pied flight pattern of leucisticBlack-vented Shearwater in San Pedro Channel, Los AngelesCounty, on 7 March 1987. Photo by Jonathan I4. Aidether

7O NOTES

Figure3. Same leucisticBlack-vented Shearwater in San PedroChannel, Los Angeles County, 7 March 1987. Photo by Jonathan I4. Alder.fer

Figure4. Sameleucistic Black-vented Shearwater on the waterwith typically plumag- ed conspecifics. Photo by gona•:hanI4. Alder.let

71 NOTES of the Cape (Daption capense)in the northern PacificOcean (filesof California Bird Records Committee) The abnormalBlack-vented Shearwater in Figure1 bore a superficialresemblance in plumageto the StreakedShearwater ( leucomelas), a vagrantto Califor- nia waters with three recordsaccepted by the California Bird RecordsCommittee (Morlan1985). However,the size,structure, and flightof the SantaMonica Bay bird convincinglyrule out the muchlarger Calonectris, with its languid flight. Inexperienc- ed observersall too oftenbase field identificationson singlefield marks(Garrett 1986) whileignoring a suiteof othercharacters that suggesta more sensibleidentification. In this case a largely whitish head might have suggestedC. leucomelas.The bird photographedby Alderfer (Figures2-4) showeda strikingwing patternsuggesting that of a Cape Petreland couldconceivably have beenmistaken for that species.Field identificationproblems within the Puffinuspuffinus complex (including opisthomelas) are well-known (Everett 1988, Harrison 1983, Jehl 1982, Morlan 1985); observers should be award of the potentialconfusion generated by plumage aberrations. I thank Arthur Howe and JonathanAlderlet for documentingthese recordsand bringingthem to my attentionand for permissionto publishtheir photographs,W.T. Everettand R.R. Veit made a numberof helpfulsuggestions after reviewingan early draft. A later draft benefitedfrom review by W.R.P. Bourne and K.T. Briggs.

LITERATURE CITED

Buckley, P.A. 1982. Avian genetics,in Diseasesof Cage and Aviary Birds (M.L. Petrak,ed.), pp. 21-110. Le• andFebiger, Philadelphia. Elkins, N. 1990. Partial albinism in Manx Shearwaters. Br. Birds 83:22. Everett, W.T. 1988. Biologyof the Black-ventedShearwater. W. Birds 19:89-104. Fluram, D.S. 1990. Partial albinism in Manx Shearwaters. Br. Birds 83:22. Garrett, K.L. 1986. Field tips: The single field mark syndrome. W. Tanager 52(5):1- 2. Harrison, P. 1983. ,an IdentificationGuide. Houghton Mifflin, Boston. Jehl, J.R., Jr. 1982. The biologyand of the Townsend'sShearwater. Gerfaut 72:121-135. Mackrill, E.J., and Yesou, P. 1988. Leucismand partial albinismin Balearic race of . Br. Birds 81:235-236. Morlan, J. 1985. Eighth report of the California Bird RecordsCommittee. W. Birds 16:105-122. Palmer, R.S., ed. 1962. Handbook of North AmericanBirds, vol. 1, Loons through Flamingos. Yale Univ. Press, New Haven. Stallcup, R.W. 1976. Pelagic birds of Monterey Bay, California. W. Birds 7:113-136. Vickery, P.D. 1978. Northeasternmaritime region. The nestingseason. Am. Birds 32:1137-1140.

Accepted 15 March 1990

72