Is that meringue in your pocket, or are you just happy to see me?
Just when I thought that I was omni-aware of all examples of “avian foam,” I learned something new, this week. Foam is found in the interior of the Toucan and Hornbill beaks, in the skull of Woodpeckers, and in the medulla of feathers. Those are more specifically avian examples of cellular solids, a sub-class of foams that are exclusively solid-fluid systems. But what most people consider to be foam is of the liquid-gas system such as that atop their glass of beer or the morning latte.
Apparently, Japanese Quails (Coturnix japonica) produce foam from their unusually pronounced dorsal-cloacal muscular gland system. “Reproductively active male Japanese quail produce a large quantity of a stiff white meringue-like foam that is transferred to the female along with the semen during copulation and also is deposited on top of the excreta during voiding.” Seiwert & Adkins-Regan (In case you missed it, you just read the words “meringue,” “semen,” and “excreta” all in one sentence).
These three foam “puffs” were manunally expelled from reproductively active male Quails. Is this sexier than Hornbill beak foam? ⓒ Seiwert & Adkins-Regan 1998/Brain, Behaviour and Evolution
Those who keep and breed Japanese Quails may have already known about this foam (e.g. the photo posted by Quail Gal), but I just found out totally accidentally. I happened to spot the word “quail” in the index of Universal Foam by Sidney Perkowitz. He writes of the “reproductive froth,” as he called it, again reinforcing that inappropriate meringue comparison, “[i]t begins as a clear viscous liquid secreted by a specialized gland, which is whipped into froth by rhythmic contractions of a sphincterlike muscle, much as rigorous beating turns egg whites into meringue.” Furthermore, electromyographic monitoring revealed heightened dorsal sphincter cloacae muscle activity which accompanied increased foam production when the male was presented with a female, even behind a screen.Seiwert & Adkins-Regan
It is great that Sidney Perkowitz also threw in the phrase “rigorous beating” in his treatment of the topic, because that is not all that is rigorous. K.M. Cheng et al. reported that based on in vitro observations, in all cases during which foam was not mixed with the quail semen, sperm motility decreased within 3-5 minutes of deposition onto optical microscope slide and ceased within 10 minutes. When foam was added to the semen, the sperm remained “vigorously motile” after 45 minutes. The authors noted that spermatozoal motility was observed still in one sample after 95 minutes under the cover slip at room temperature.
The reproductive foam is nothing personal, but it is specific. Semen samples were mixed with foam secretions of the same donor as the sperm and of other donors as well, and the results were that any Japanese Quail’s foam would do.K.M. Cheng et al. However, mixing quail froth with chicken or turkey semen either did not affect sperm motility or fertility or possibly adversely affected motility (according to the M.S. thesis of one of the co-authors of the study). Turkeys produce a cloacal foam of their own which was not found to affect motility of sperm.Fujihara et al. Among accessory reproductive fluids in birds, the case of Japanese Quail is unique in that the foam is produced constantly, released simultaneously with seminal ejaculation, and it helps by increasing and prolonging spermatozoal motility.