Diversity in chemical compositions of preen gland secretions of tropical birds

The chemical composition of preen gland secretions of antbirds (Thamnophilidae and Formicaridae) and phylogenetically closely related Dendrocolaptidae, Tyrannidae and Pipridae were investigated to understand the role of environment in secretion components. The secretions of Thamnophilidae consisted of long chain acids, alcohols, esters, unsaturated hydrocarbons, and isoprenoids. Formicaridae secretions contained exclusively squalene and its derivatives. In Pipridae, secretions were made up of complex long chain esters. In Dendrocolaptidae, the secretions consisted of long chain esters of both saturated and monounsaturated acids combined with mono-alcohols and those of Tyrannidae consisted of long chain esters of saturated, mono- and tri-unsaturated acids with mono- and di-ols that were less complex. Higher molecular weight saturated and unsaturated components in tropical species suggest that the volatility of the secretion components is correlated to environmental temperatures experienced by the birds. Squalene is a precursor in steroid biosynthesis, but higher amounts in Formicaridae secretions suggest that it may have some additional functions.