Musth is a natural periodic condition occurring in male (bull) elephants of both the Asian and African species. During a musth cycle, bulls typically experience an extraordinary hormonal surge, with their testosterone levels increasing to, on average, 60 times higher than their pre-musth levels. Musth is also marked by a significant increase in aggression and hostile behaviour, as well as chemical and olfactory signalling. The characteristics of high aggression and behavioural unpredictability, combined with the fact that musth is a temporary, cyclical phenomenon, must have been accounted for when the condition was first named: ‘Musth’ (pronounced “must”) is an Urdu word derived from the ancient Sanskrit word ‘mada’, meaning “intoxicated, excited” – in other words, “drunk.”
Physically, the changes induced by musth are significant and unique. One of the most obvious visible signs that a bull is in musth is the secretion of a thick, hormone-rich fluid from the temporal glands, located between the eye and ear on each side of the head. This substance, known as temporin, has a distinctive, strong odour. A bull may use its trunk to smear the secretion on its head and body, as well as on objects such as trees, using it as a chemical and olfactory marker to demonstrate dominance to males, and attract mates in oestrus – female elephants will almost invariably exhibit a preference to breed with males currently in musth. Another physical symptom of musth is a constant trickle of strong-smelling urine, which coats the elephant’s legs and the ground. This is another form of scent marking.
The initial onset of musth occurs at around 20 years of age in Asian elephants, often with somewhat weak effects, which increase in strength over the course of subsequent musth cycles. In wild bulls, musth generally occurs annually, lasting a period of 2-3 months, and a regular musth cycle generally signifies good health and adequate nutrition. Physiologically, the musth state is extremely strenuous and cannot be sustained for extended periods of time, except by the healthiest, most robust males.
Musth is a natural cyclical condition occurring in bull elephants which causes a massive, temporary hormonal surge and a marked increase in aggressive behaviour. In a previous post, we discussed the physical symptoms of musth, and examined some of the individual behaviours. Now, we will talk about how musth affects social interactions between elephants.
Once male Asian elephants reach puberty and exit their maternal herds, they generally lead a predominantly solitary existence. In some cases, bulls will form small all-male herds, usually with other elephants of approximately equivalent age, though due to the competitive nature of breeding in the species, associations and bonds within these groups tend to be loose and quite weak (certainly much weaker than the highly developed familial bonds seen in all-female groups). All-male groups are thought to consist of similarly aged bulls due to the inability of young elephants to compete with older, larger males for access to reproductively receptive females.
Even if an elephant typically roams in an all-male herd, upon entering musth they will typically spend little, if any, time with their associates. Dominance amongst bulls is usually determined by size, but the surge of hormones and aggression in bulls experiencing musth may allow them to gain an advantage over and dominate even much larger non-musth males. If two male elephants in musth meet, they will almost certainly clash, and have been known to fight to the death.
While not in musth, male elephants over 30 years of age tend to spend more time with other males than younger bulls. It is thought the purpose of this association is to frequently test their strength against other elephants with a similar likelihood of entering musth in any given year. Interestingly, the elephant with the most dominant status may have a greater chance of entering musth. In at least one study on domestic Asian bulls, only the dominant male in a domestic group of bulls was observed to enter musth for several consecutive years. Research on whether this sociobiological phenomenon occurs in wild populations is currently inconclusive.