Superior Oxidative Status in Leucistic Cinereous Vultures

AbstractGiven the usually dark colors that melanin pigments confer to the plumage of birds, local depigmentation creates conspicuous plumage patterns with white feathers that are commonly termed "partial leucism." Such color aberrations have been adduced to urbanization in some species of birds, tentatively assigning the potential of pollutants to induce oxidative stress as a causative agent. White feathers, however, can be produced by a lack of melanocytes in feather follicles without the course of oxidative stress. In contrast, the appearance of white feathers with age is caused by the oxidative stress-induced impairment and death of melanocytes. Both mechanisms are often confounded because the oxidative status of birds with white feather anomalies has not been investigated. Here we compare the cellular oxidative status of wild partially leucistic cinereous vultures (Aegypius monachus) with that of normally pigmented vultures using levels of malondialdehyde (MDA) in plasma, a product of lipid peroxidation. Leucistic vultures exhibited significantly lower MDA levels than normally pigmented birds, arguing against a causative role of oxidative stress in bird leucism, at least in raptors. As similar positive effects of leucism on the systemic oxidative status have previously been found in mammals and fish, these findings suggest that partial depigmentation may benefit animals and stress the importance of identifying the depigmentation mechanism to interpret the context in which color aberrations occur.