Apparent selective advantage of leucism in a coastal population of Southern caracaras (Falconidae)

摘要: Background: Southern caracaras are medium-sized raptors with a large range stretching to the southern tip of South America. An aberrant, leucistic plumage is found commonly along coast Chubut Province (Patagonia, Argentina). Leucistic birds do not produce dark melanin in their feathers. However, they albinos because eyes red. No genetic studies caracara plumages known. Hypothesis: The high frequency arises natural selection. Methods: Map distribution individuals relative normal individuals. Combine variety anecdotal history observations, collected over 20 years, into logical inference. Observations: were only 250-km stretch rocky oceanic islands and continental outcrops seabird colonies Province. In rest range, have plumage. Where occur, frequent co-occur dark-plumaged birds. Intermediate individuals, presumably