Discolored and worn-out plumage in juvenile Magellanic Penguins (Spheniscus magellanicus) found ashore in southeast and northeast Brazil

Abstract

Magellanic Penguins (Spheniscus magellanicus) are common winter visitors of the Brazilian continental shelf. In this study we report the occurrence of discolored and worn-out plumage in juvenile Magellanic Penguins washed ashore during summer on the southeast and northeast coast of Brazil. In the affected individuals, the areas of the plumage that would normally be black or dark grey were discolored to tones ranging from brown to cream-white, especially on the head and dorsum. Upon close examination, the feathers were often brittle and appeared “old” and worn-out, at times leading to irregular and asymmetric patches of feather-loss in the lower back. We propose five factors that could be involved in causing this condition: (a) molt skipping, (b) sun exposure, (c) malnutrition, (d) insufficient preening, and (e) chewing lice.