51�Թ�

But juncos likely aren’t making their perfume alone: Lots of those preen gland chemicals are naturally made by bacteria.

The embryo's survival may be enhanced by the odorous, oily secretions of the mother's preen gland that grease the eggs' shells during laying and incubation.

The uropygial or preen gland is found in the majority of birds and is situated near the base of the tail.