My colleague, mammal vocalization expert David Reby (now at the University of Sussex), and I discovered that male red deer (Cervus elaphus) have an unusual vocal adaptation: a permanently lowered larynx (previously believed to be unique to humans). This is the large lump you can see about midway down his neck. But as this video shows, during roaring stags pull the larynx down even further, to its anatomical limit at the entrance to the thorax. This makes the roar sound more impressive by lowering formant frequencies.
See: Fitch, W.T. and D. Reby, The descended larynx is not uniquely human. Proceedings of the Royal Society, Biological Sciences, 2001. 268(1477): p. 1669-1675. (available as PDF)
Many more fascinating papers on deer vocalization in this and other species are available on David Reby’s website
Dynamic Laryngeal Descent in Red Deer:
Meet “Bambo”: an adult red deer (Cervus elaphus) stag, and – during the mating season – a dangerous 200 kg of raw testosterone. This captive stag has his horns removed for the protection of the farmer who is raising him. Note the lump in the front of the neck, which is the larynx begin lowered (and try your best to ignore the penis-pumping, which does not appear to have any acoustic function):
This video shows the low resting position of the larynx quite clearly.
Laryngeal Descent in other deer species
Wapiti (Cervus elaphus canadensis, or according to some authorities Cervus canadensis, a separate species) also lower the larynx during bugling, as shown in this video (which I made with night vision in New Zealand). You can see the larynx return to a higher position when the call finishes. Although the main portion of this call is the high-pitched bugling, at close range you can also discern formant frequencies:
Finally, at least some closely related species do NOT have a permanently descended larynx, like this Pere David’s stag (Elaphurus davidianus, filmed at the Scottish Deer Centre).
This species, apparently, has a “normal” high resting position of the larynx, and lowers it only during groaning calls.
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