Plumage coloration and morphometrics of the Little Owl Athene noctua in the Western Palearctic

The Little Owl is a species with a wide range in the Palearctic. Thirteen subspecies have been described based on small coloration or size differences. Recently, genetic studies in the western portion of the European range have shown the presence of some well distinct clades. We examined the variation in structural size and coloration of Western Palearctic birds, with particular attention to the pattern of light and dark pigmentation on the tail, and we checked for the presence of UV reflection through reflectance spectroscopy. We did not find clear-cut differences in size or plumage between the currently accepted subspecies, nor between individuals pertaining to the different genetic clade areas. There is a trend for individuals from the western genetic clade (Iberia, France, England and central Europe) to have longer tarsus with smaller wings, while individuals from the eastern generic clade (Balkans) have an opposite pattern. Italian birds are intermediate. The tail of Balkan birds has a wider dark pigmentation, with reduced light spots. Little owl feathers do not show reflectance in the UV part of the spectrum. We found a very large variation of morphological and color patterns between individuals collected in the same geographical area. Currently, the arrangement of individuals to any Little owls' subspecies on morphological data appears to be a very difficult task.