Galvan and Sanz (2006) have provided evidence of the possible relationship between the number of feather mites and the uropygial gland size in a breeding population of great tits Parus major.
However, not all lipids of the plumage originate in the uropygial gland; a proportion comes from the sebaceous secretions of the epidermis.
In considering the physiological role of the uropygial gland, it appears that the gland is not necessarily present in all groups of birds.
These results suggest that the uropygial gland may not relate, at least physiologically, to the homeostasis of lipids or to the regulation of calcium metabolism.
These results suggest that the toxicity of lipophilic products may be regulated by the uropygial gland, which would have the role of capturing and depositing these substances.
It is possible that the heavy metals found in feathers may originate either from internal deposition or through the secretion of the uropygial gland during preening.
The uropygial gland specializes in the synthesizing of lipids.
However, this provides the means to establish that the uropygial gland is a very variable organ in regard to morphology, chemical composition of its secretion, and the variety of functions it is involved in.
Roles of adrenal and gonadal steroids and season in uropygial gland function in male pigeons, Columba livia.
Influence of fowl uropygial gland and its secretory lipid components on the growth of skin surface bacteria of fowl.
Influence of fowl uropygial gland and its secretory components on the growth of skin surface fungi of fowl.