Studying the uropygial gland and its secretions sheds new light on this relatively unknown organ, a gland that is characteristic of birds. It produces a wax that is believed to protect their feathers from external aggressions.

1/8 Most bird species have an organ called the uropygial gland. It is common to see a bird use their beak to remove the wax produced by the gland, located at the base of the spine. They then use the wax to polish their feathers. Pixabay

2/8 A uropygial gland in Barn Owls © Jeremy Bierer

3/8 We study variations in the size of the gland between individuals. © Jeremy Bierer

4/8 We take samples of the wax by stimulating the gland. Using a glass capillary tube, we collect several microliters of the wax in order to study its composition. © Jeremy Bierer

5/8 The secretions are immediately treated for storage. © Jeremy Bierer

6/8 To prevent the samples from degrading while in the field (in the nestbox) and the lab, they are stored in ice. © Jeremy Bierer

7/8 We also take a few feathers in order to study any microbes we might find on them. © Jeremy Bierer

8/8 Feathers are collected with gloves and placed in sterile bags to prevent any contamination from our own microbes. © Jeremy Bierer

A special organ

Most bird species have an organ called the uropygial gland. Located at the base of the spine, on the bird’s croup, this gland secretes a kind of wax that the birds use to polish their feathers. It is thought the wax serves to maintain and protect the feathers, but this hypothesis is still currently debated.

Revealing variations

We study this gland in Barn Owls by analyzing how its size varies and the differences in the chemical composition of the wax between individuals. Sometimes the size of the gland and the composition of the wax vary according to the sex of the individual, its age, the period of the year, or even the color of its plumage. In fact, given that the melanin pigments make the plumage rigid, it is possible that the feathers of darker owls need less care, or a different care, than the feathers of lighter owls.

Study of the antibacterial properties of the wax

We also look more specifically on the potential protective function of the wax. A bird’s feathers are naturally infested with bacteria that consume keratin, a feather’s primary material. In other words, these bacteria can eat the feathers. We look to understand if the wax produced by the uropygial gland in Barn Owls has antibacterial properties. To do this, we conduct chemical analyses looking for any antibacterial components in the wax.