Composition of uropygial gland secretions of birds of prey.

The chemical composition of the uropygial gland secretion of five species of birds of prey was investigated by gas liquid chromatography-mass spectroscopy technique, and the results are discussed from the chemotaxonomical point of view. The secretion is a complex mixture of monoester waxes, the fatty acids of which are mainly dimethyl-branched, with the first substituent in 2 position and the other near the methyl end of the molecule. Mono-, trimethyl-, and unbrached fatty acids also are observed. The wax alcohols are mainly mono- and dimethyl-substituted. Unbranched alcohols and traces of trimethyl-substituted alcohols also were detected. Chemotaxonomically, the birds of prey differ from all orders hitherto investigated. The degree of substitution increases from the Falconidae to the Accipitridae.