Imperfect Albinism in a Sandhill Crane
Imperfect Albinism in a Sandhill Crane.-On April 2, 1958, during the height of the migration of Sandhill Cranes (Grw c densis) through central Nebraska, the writer observed an extremely light-colored individual of this pecies in a group of some 1M) cranes feeding in a field along the Platte River, two miles south of dessa, Buffalo County, Nebraska. The bird in question was markedly paler than any of its companions and when first observed from a distance of approximately one-half mile, it stood out in strong contrast to the group.
On closer observation it was readily determined that the bird was definitely not a total albino, but possessed a pale or diluted version of the normal plumage. The characteristic mouse gray color of the feathers was replaced by gray of an extremely light hue. The red coloration on the bare areas of the head also appeared to be paler. In all respects this individual seemed to express the phenomenon of imperfect albinism or dilution, wherein a paler than normal coloration is due to a more or less general reduction of pigmentation throughout the entire plumage (Hutt, Genetics of the Fowl, 1949: 187). The term schizochroism has also been applied to birds having “the normal plumage pattern of the species but an abnormally pale, washed-out appearance” (Van Tyne and Berger, Fundamentals of Ornithology, 19S9:99-100). Imperfect albinism has been recorded for a variety of domestic and wild birds, including the Mourning Dove (Zenaidzrra macroura), California Quail (Lophortys californicus), and Redwinged Blackbird, Agelaius ph0ekeu.s (see Nero, Auk, 71, 1954:137-155). Experimental evidence indicates that in some of these species a sex-linked recessive factor is responsible for the dilution effect.
There appears to be no previously published record of albinism in the Sandhill Crane. The subject is not mentioned in Walkinshaw’s monograph on the species (The Sandhill Cranes, Cranbrook Inst. Sci. Bull. No. 29, 1949). Walkmshaw has further remarked (personal communication) that he has never observed true albinos, although he has encountered some birds with partial albinism in which a few white feathers are present.
At the time of the original observation, the writer was impressed with the possibility that chance viewers might readily mistake such pale mutants for the rare Whooping Crane (Grus americana) ; however, it would appear that albinistic individuals are of such very infrequent occurrence that the possibility for mistaken identity would seldom be presented.-JOSEPH R. MURPHY, Department of Zoology, University of Nebraska, Lincoln, Nebraska, December 4, 1959.
