Tuesday, August 20, 2013

Might makes right (unless you're in musth)

I’ve heard a lot of excuses for not showing up to an experiment, but today has to be the first time “I’m in a hormonal rage” has ever made the list. Somjai, one of the newest and largest members of the GTAEF family, is a magnificent bull elephant in his early twenties. He’s currently a research superstar: easy to train, quick to understand the task, and delicate with our equipment, leaving behind only copious amounts of snot where other elephants have laid down a trail of broken hinges and battered bars. This mild-mannered gentleman makes it easy to forget that bull elephants can be extremely dangerous to work with, especially when they enter their annual state of musth.

Photo credit: Elise Gilchrist

Pronounced with a silent h (and a healthy amount of respect), musth is a periodic condition unique to male elephants, lasting anywhere from a few weeks to several months and characterized by aggressive behavior and a spike in reproductive hormones. Physical signs of musth include drastic swelling of the temporal glands (small holes located between the ear and the eye on the elephant’s head) which begin to leak a pungent, oily liquid. Some hypothesize that this free-flowing ooze, containing temporin, travels all the way to the elephant’s mouth and that the taste of their secretions is part of what drives the bulls’ heightened sense of agitation. Even more attractively, a bull’s genitals begin to leak urine almost constantly, eventually giving the penis a greenish tinge. Though not exclusive to musth, anorexia, dehydration and drowsiness can also commonly occur during this time.

Leaking temporal gland of a bull in musth
via Wikimedia Commons

Behaviorally, a bull in musth is unpredictable, irritable, and highly aggressive, posing a danger to any human, elephant, or unfortunately placed object they come into contact with. Testosterone production skyrockets, and some estimates place hormone levels at 60 times their normal amount! Males in musth also produce special musth rumbles, which are louder, lower, and much more guttural than a typical greeting rumble. Though males show increased signs of virility during this state, as well as increased investigation of females’ reproductive state, musth is not necessary for conception; males successfully impregnate females when not in musth, casting some doubt on the theory that the condition is entirely sexual in nature.

Scientists are still unsure of what triggers musth, though some evidence exists that the presence of females can encourage its manifestation. Older males have also been shown to inhibit musth in males who are just maturing, or at least curb some of their more aggressive impulses. The onset of musth is typically earlier in captive males than those in the wild. A teenage bull’s first musth is usually his shortest, and the temporal gland secretions smell sweet like honey, which is thought to signify their status as non-threatening to older, larger males. As the male matures, his periods of musth lengthen and become more regular, so that by the time a bull is in his thirties, his musth is occurring around the same time each year. There is no coordinated musth in males, though a higher number will enter the state around the rainy season. 

Male in musth investigating female
via Wikimedia Commons

This absence of synchronicity is thought to contribute to genetic diversity, since a male in musth has priority access to the females. Even the most dominant bull is second in line behind a lusty, musth-y male when it comes to courting a mate. If multiple bulls are in musth at the same time, priority once again falls to the most dominant; because the annual musth schedules of males in the bachelor herd are naturally staggered, the system affords a larger number of bulls the chance to reproduce, adding more variation to the gene pool.

The energetic demands of musth also ensure that only males who are healthy enough to maintain the heightened physiological state can take advantage of this reproductive strategy. Producing astronomical amounts of testosterone places a huge burden on the elephant’s body, requiring them to consume vast quantities of food rich in calories. In fact, the duration of musth is often shortened in captivity by providing the male with only a bland diet of grasses. By cutting out the typical treats like fruits and sugarcane, caretakers can reduce the period of musth to a few weeks. Without the sugars and carbohydrates, the elephant isn’t able to maintain the hormonal overproduction.

Male in musth
via Wikimedia Commons

So what does this mean for the gallant Somjai? His breakfast will be a bit more bland and boring, and his social calendar will be suddenly clear for the next couple of weeks. As much as we love watching his mind at work, it is safer for all people and pachyderms involved if Somjai spends his musth filled days up on the mountain, alone with some birds, trees and his hormonal angst.


Asian elephant, Elephas maximus. (2008, July). Retrieved from http://library.sandiegozoo.org/factsheets/asian_elephant/asian_elephant.htm

Fowler, M., & Mikota, S. (2006). Biology, medicine, and surgery of elephants. Ames, IA: Blackwell Publishing.

Indian elephant in musth by Yathin S Krishnappa via Wikimedia Commons
Asian elephant by Herrick via Wikimedia Commons
Thai bull elephant in musth by OxOx via Wikimedia Commons

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