.--While banding raptors on Martha's Vineyard Island, Massachusetts, I captured six adult Red- tailed Hawks (Buteo jamaicensis) between 28 March and 31 March 1973. All the birds were year-round residents; when caught they were hunting with or near their mates. One bird was a recapture from 30 March 1972, caught 500 yards from the spot where it was taken the year before. The bird that was recaptured was an extremely light individual, with a pure white breast and an almost pure white head. The wing feathers molted in 1972 showed a very striking "red" (similar to the tail) color, which was not present in the previous year's plumage. When Brown and Amadon (1968, Eagles, hawks and falcons of the world, New York, McGraw-Hill Book Co., p. 41) stated that erythrism is known in Red-tailed Hawks, they were referring to the reddish phase of the western subspecies, B. j. calurus, not to the unusual situation developed in this individual. The bird showed the erythrism in the wing feathers only, par- ticularly the primaries and secondaries, but also in the upper wing coverts and alulas. The melanoblasts, a migratory element from the neural crest in early embryonic development, are secondarily located at each feather follicle, where they produce the color and perhaps the pattern of each feather. The melanoblasts normally act in one manner for the immature plumage and then in a different manner for the adult plumages. The recapture of this individual demonstrates that they can act in a third fashion. The fact that each greater covert of an erythristic remige is erythristic itself suggests that the migrating melanoblasts for each remige and its covert form a unit. While processing the birds, I noticed that five of the six had not completed the wing molt from the year before. Body and tail molts were complete. Both primaries and secondaries that were a year older than adjacent feathers were TABLE 1 IRREGULAR AND INCOMPLETE WING MOLT IN FIVE OF SIX RED-TAILED HAWKS Primary Secondary Band no. Capture date 1 2 3 4 5 6 7 8 910 1234567891O 877-12704 30 March 72 : All new L: All new 31 March 73 : N N N N N N O O N L: N N N N N N O ON 877-12713 28 March 73 : N N o N x o o N o L N N 0 N N 0 ON 0 877-12714 28 March 73 All new 877-12716 28 March 73 R: X N X N O O N O N L: N ON O N  O N N N 877-12717 29 March 73 R: N N N N O N N O N L: N N N N O N N ON 877-12718 31 March 73 I: o N o N N o o N N L: ON O N N O O N N N N O O N N O O O O N N O N N N O O ON N O ON O 0 X N N N N N O O N N N O N N N O N 0 O N N O O O N N N N N O N X O O O N N N All new O O O O O N N N N N N N 0 0 0 0 N N N N N N N N N' N O N ' N O N N N N N N O N N N O N N N ON O O O O O N N N N O O ON ON O N N N feather grown in during the last molt, O = feather not molted in the last molt. readily apparent from the pattern of the previous molt Irregular molting of the mann and Stresemann 1960, Buteo, of all Accipitridae Elaninae. The Stresemanns pronounced bleaching and wear of the vanes. The was not sequential in four of the five (see Table 1). primaries and secondaries has been reported (Strese- J. Ornithol. 101: 373-403) for certain genera, including subfamilies except Circinae, Milvinae, Perninae, and suggested that this molt pattern evolved from the primitive pattern of molting primaries 1 through 10 in sequence in order to reduce the stress on ingrowing feathers and to minimize the loss of flight efficiency. Certain large eagles are reported to take more than a year to complete a wing molt (Spofford 1946, Auk 63: 85), but I have seen no account of this phenomenon in Butco. Presumably these birds stop molting sometime in the fall in order that no feathers will be growing in during times of food shortage. Several factors suggest that prey is abundant year-round on this island; these include the mild climate (snow cover rarely lasts more than a few days), the fact that the entire Red-tail population (between 10 and 20 pairs) appears to be nonmigratory, the large num- ber of migratory raptors that winter on the island, and my own snap-trapping data. I would be very interested to compare data with anyone who has similar observa- tions of resident or wintering raptors showing incomplete molts. I thank Dean Amadon and Walter Spofford for their comments and suggestions on the manuscript. These observations were made while conducting a research project supported by the Harris Foundation.--RICAm) O. BIERREGAAm), JR., C/O Felix Neck Wildlife Sanctuary, Box 1055, Oak Bluffs, Massachusetts 02577. Accepted 15 Jun. 73.