Preen Gland

Gland secretion

The uropygial gland secretes an oil (preen oil) through the dorsal surface of the skin via a grease nipple-like nub or papilla. The oil contains a complex and variable mixture of substances formed greatly of aliphaticmonoester waxes, formed of fatty acids and monohydroxy wax alcohols. However, some types of diesterwaxes called uropygiols and containing hydroxy fatty acids and/or alkanediols exist in the secretions of the uropygial gland of some groups of birds. Preen gland secretion of some, but not all, birds have shown to be antimicrobial. Some birds harbor bacteria in their preen gland, which to date, have (exclusively) been isolated from preen glands (e.g. Enterococcus phoeniculicola and Corynebacterium uropygiale). Some of those bacteria add to the antimicrobial properties of preen wax.