The bat family [Emballonuridae], also called sac-winged bats, have bag-shaped glands in each wing that are open to the air. During courtship, males wave their wings in front of the females for a few seconds, dispersing the scent that comes out of these bags.
[...] The team discovered each animal emits an intense odor that broadcasts the chemical composition of what is known as their major histocompatibility complex, or MHC, genotype.
— Read more at Bats Use Body Odor to Sniff Out the Best Mates at Scientific American.
Fascinating! It makes perfect sense that bats would use scent to communicate through the air and disperse it with their wings.
I recently watched The Sagebrush Sea on PBS which showed the grouse that live there. The narrator wondered how a female grouse could find her mate over and over again; the birds all seem to look alike (to people). I’m sure grouse can tell one another apart by sight but as I watched I imagined the female must use scent to find her partner.
I wonder . . . 😉
Oh, good question.