A Study of Two Plumage Aberrations in the Male Redwinged Blackbird (Agelaius Phoeniceus)

Abstract

Two different traits of albinism were studied in samples of male Redwinged Blackbirds. Eighty-eight per cent of 627 male Redwings sampled possessed a white spot at the base of the rectrices, the size of this white area being smaller in the immature redwing males than in the adults. Samples of immature males after they had obtained first basic plumage revealed a white spot size distribution essentially the same as that found in the adult sample. Breast banding, the other trait studied, was found to occur in 5.2 per cent of the adult males sampled.