On Partial Melanism Associated with Parathyroid Enlargement in Pigeons

Abstract

Five cases of non-genetic partial melanism were observed in adult female domestic pigeons. One similar case was observed in an old male hybrid (Zenaida x Zenaidura) dove after it became unable to fly. Two physiological conditions, slight exposure to sunlight and enlargement of the parathyroids, were known to be associated with all of these six cases of melanism. It is considered probable that these conditions were also responsible for previously reported instances of melanism in caged wild birds. In two instances plucked melanistic feathers were replaced by normal feathers following the administration of a concentrate of cod-liver oil (vitamin D). Parathyroid enlargement is shown to occur regularly in young pigeons reared on a mixed grain diet in the absence of direct sunlight (vitamin-D deficiency). Grossly defective ossification of the bones (rickets) of many such pigeons is reported.