HYBRIDIZATION

A presumed Bufflehead x Hooded Merganser hybrid in Illinois Walter J. Marcisz

Male Buffleheadx Hooded Merganserhybrid with female Bufflehead, PowderhornMarsh, Chicago, Illinois, May 4, 1980. Note black border on rear portion of hybrid's white crown patch. YBRIDIZATIONisof unusually fre- panied by a bird assumedto be its mate. result of the onset of eclipse plumage quent occurrence among the Closer inspectionof the male bird, how- (the accompanying q) Bufflehead also various members of the family Anati- ever, revealed a black border on the rear seemedto have a very slight suggestion dae. Interbreeding has not only been portion of its white crest. The bird was of this vertical bar). The male's flanks known to occur between different tentatively identified as a o' Hooded and sides were grayish. Its tail, which species, but also between different Merganser, until it was noticed that it was sometimes cocked up at an angle, genera and even different subfamilies. had a rather short, Bufflehead-like bill. Hooded Merganser-style, was blackish. The Mallard (Anasplatyrhynchos) alone It was then confirmed that the bird in- In general, the coloration of the bird's has been known to hybridize with ap- deed behaved as if it were paired with plumage was rather washed-out. When proximately forty other species. The the q)Buffiehead, and upon closerexam- observedin flight, the bird's upper parts Wood Duck (Aix sponsa) is also a fre- ination, the male bird was found to pos- (including back, rump, tail, and upper quent interbreeder,having been known sessphysical characteristics of both the wing surfaces)were dark dusky or black- to crosswith over twenty species(Johns- Bufflehead and the Hooded Merganser. ish, except for the speculum, which was gard, 1968). By far the greatest amount Later that day I photographed both white. In flight, the bird's upper wing of waterfowl hybridization has been birds. Following is a description of the pattern basically resembled that of a q) among captive birds, but interbreeding male bird based on notes taken at the Buffiehead. involving wild birds, although lesscom- time of observation and subsequent The presumed hybrid was observed mon, also occurs. The following is an examination of photographs: the bird swimming and diving with its mate. On accountof a free-flying bird observedby was basicallythe sizeand shapeof a Buf- at least one occasion, the two birds flew the author, presumed to be a cross be- fiehead, and had the large, rounded around the marsh for a few brief tween the Bufflehead (Bucephala head and short, steep bill characteristic moments and then alighted on the water albeola) and the Hooded Merganser of that species.The head and much of its again, not far from their point of origin. (Lophodytes cucullatus), birds of two neck were black, with the exception of Neither bird engaged in any vocaliza- distinct subfamilies (Athyinae and Mer- the large, black-margined white patch tions. After about fifteen minutes, the ginae, respectively). To the author's previously mentioned. The bill was dark two birds flew off together and landed knowledge, this particular combination gray or blackish, and the iris was dark. near the center of a larger lake, where has not been recorded previously, al- The bird's lower neck, back, and wings they could not be well viewed. The auth- though the Common Goldeneye (B. (when at rest) appeared of dark, dusky or returnedthe following afternoon, but clangula), a close relative of the Buf- grayish or brownish. The breast was neither bird could be located. fiehead, occasionally hybridizes with the whitish, with a small amount of darker Hooded Merganser (Kortright, 1943). mottling. On the side of the breast was HEPRESUMED HYBRID was observed At about 3:45 p.m., on May 4, 1980, the suggestionof a dark vertical bar ex- with 7 X 35 wide angle binocularsat the author arrived at Powderhorn tendingdown from the bendin the wing. an estimated distance of 150-200 feet. It Marsh, Chicago. At this time, a q) Buf- It is not clear whether this bar is indica- was viewed on a bright, clear day with fiehead was observedswimming in open tive of Hooded Merganser ancestry or the sun's illumination coming from the water in a marshy area. It was accom- merely a plumage variation, perhaps a left of the author as he observed the bird

340 American Birds, May 1981 Hybrid's bill shapeis mostsimilar to typicalBufflehead bill shape. Note hybrid's (left) dark wings, back, and tail; white speculum.

(side lighting). nest in tree cavitiesand occupy partially The author subsequently examined overlappingbreeding ranges. These facts the two drawers of Bufflehead study tend to support the possibilitythat these skins at the collection of the Field Muse- two speciesmight occasionallyhybrid- um of Natural History in Chicago, but ize. could not find any bird (including eclipseplumage specimens) which signif- LITERATURE CITED icantly resembledthe presumed hybrid. BELLROSE, F.C. 1976. Ducks, Geese, and None of the cy Bufflehead skins exam- Swans of North America. Harrisburg, ined had even a suggestionof the black Stackpole Books. JOHNSGARD, P.A. 1968. Waterfowl, Their border observed on the rear portion of Biology and Natural History. Lincoln, the hybrid's white crest. This character- Univ. of Nebraska Press. istic was present, however, on skins of KORTRIGHT, F.H. 1943. The Ducks, Geese breeding plumage cy Hooded Mergan- and Swans of North America. Washing- ton, D.C., American Wildlife Institute. sers examined.

Presumed Bufflehead Jr Hooded Merganser According to Bellrose(1976), both the --1418 Brown Ave. #16, hybrid. All photos by Walter J. Marcisz. Bufflehead and the Hooded Merganser Whiting, Indiana 46394.

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