Musth

Bull elephants annually cycle between a state of heightened aggressiveness, called musth, and non-musth. A musth elephant is primed to mate, and fights other bull elephants, attacks other animals, and may destroy inanimate objects in its way. Musth bulls produce a distinctive low-frequency vocalization, the musth rumble, have thick secretions from their temporal glands (the duct from the temporal gland opens between the eye and the ear), and continuously dribble urine. Testosterone levels are at a peak in musth males and probably regulate this extreme form of reproductive behavior.

Legendary "rogue" elephants were probably musth bulls, redirecting their aggression at random objects, including villages and the people in the villages.

Young bulls do not go into musth, and may be inhibited from doing so by older males. Asian elephant males start their musth cycles by the time they are 20, but African elephants do not reach this stage of maturity until they are 25 or so years old.

Musth has implications for maintenance of captive populations of elephants in conservation programs. Musth males are unmanageable and extremely hazardous to elephant handlers.

Musth is an interesting reproductive strategy. Presumably, males cannot maintain themselves in this physiological state for extended periods of time. In a sense, it might be a handicap, as only well-fed, healthy males may be able to physiologically support the energetic demands of being musth. When more than one bull is in musth, fights, with risk of serious injury, result. Bulls may adopt a strategy of avoiding fights by coming into musth out of synchrony with stronger or more powerful bulls, but female ability to conceive is highly seasonal, so an elephant whose musth is poorly timed may sire few offspring. Bulls which exhibit off-season musth are displaying a type of satellite strategy, in which their mating efforts are peripheral to the main mating competition.