The elephant's temporal glands are a pair of modified sweat glands located on each side of the head between the eye and the ear. The onset of musth can be seen from swelling of the temporal glands and the secretion of fluid (the musth fluid), which streams down the cheeks of the animal (fig. 3.4). There are different stages in the manifestation of musth. Toke Gale describes four stages of musth based on his observations of Burmese timber elephants.
Based on this description and other observations in captive and wild elephants, the typical progression of musth is as follows. During the early stage, the temporal glands swell slightly and are clearly visible as small dark patches. When the temporal glands begin to secrete, the fluid is watery and flows down the cheeks as a thin streak 7-10 cm long. Later, the temporal glands swell considerably and discharge more copiously. The pungent-smelling fluid during the "full-musth" phase may be more viscous and stains a wide area of the cheeks, even flowing down to the corners of the mouth. The Burmese term this last stage the "musth drinking stage." At this time, the bull also begins to dribble urine, either as discrete drops or in a regular stream. A particular odor is also associated with the urine discharged when a bull is in musth. When a bull has been urinating for an extended period of time, the proximal part of the penis and the distal end of the sheath show a greenish coloration, termed the green penis syndrome by Joyce Poole and Cynthia Moss. These physical manifestations of musth may last from a few days to months, depending on the age and condition of the bull.
It is well known in Asia that captive bull elephants in musth become aggressive and fail to respond to commands from their keepers. Thus, bulls are almost invariably kept restrained for the duration of their musth phase. Observations of musth behavior in Asian elephants have largely remained anecdotal or descriptive. Joyce Poole's accounts of the behavioral ecology of musth in Amboseli's elephants remain the most detailed so far. These include several behaviors, postures, and vocalizations performed almost exclusively by bulls when in musth. I briefly describe some of her observations and supplement them with what is known about musth behavior in Asian elephants.
Musth walk: A musth bull may walk with its head held high, at an angle such that the chin looks tucked in, and the ears spread and motionless. This, combined with a swinging motion to the head and tusks while walking, would project a formidable image of a musth bull to its opponents.
Tusking: At Amboseli, males in musth were observed going down on their knees to tusk the ground, throwing up lumps of mud or grass. This behavior occurred invariably during fights between bulls in musth. I have observed a variant of this tusking behavior in Asian bulls. A musth male would gently press his tusks against an embankment, and the temporal glands would visibly discharge fluid. A more frenzied act of digging the tusks into the bottom of a pond was once observed in a young bull probably experiencing musth for the first time.
Marking: Although male elephants rub their temporal glands against trees when in musth and out of musth, they were seen at Amboseli to rub their glands much more frequently when in musth. This behavior has also been seen in Asian elephants and may serve to scent mark an individual's identity.
Ear wave: In contrast to other ear signals, when both ears are flapped, a musth bull performs the ear wave by moving only one ear at a time. The inner and upper portion of the ear is thrust forward suddenly, with the outer and lower portion of the ear following. It is speculated that this serves to waft the scent of the musth secretion forward toward other elephants. This behavior has not been reported among Asian elephants. It is possible that only the larger-ear African bulls are able to perform this motion, or that such an act is less frequent and may have been overlooked in Asian bulls.
Musth rumble: Elephants communicate at low sound frequencies (infrasound) that travel over longer distances without attenuation (see chapter 4). African savanna bulls in musth give a distinct set of calls with frequencies as low as 14 Hz (hertz) and sound pressure levels up to 108 decibels (at a distance of 1 m). A musth rumble is usually performed in conjunction with the ear wave. Musth males vocalized more frequently when alone than when they had already joined a family group. Younger males (under 40 years) rumbled only about once every hour, while older males did so about three times more frequently. Female elephants respond to a male's musth rumble with their own characteristic low-frequency sound.
Urination with sheathed penis: Bulls in musth, which dribble urine at a low rate for more than an hour, urinate with the penis retracted within the sheath such that the urine is sprayed onto the insides of the hind legs.
These behaviors basically serve either to repel potential competitors or to attract estrous females. Thus, an aggressive posture with the head held high or scent marking by rubbing the temporal glands on trees may deter other large bulls, while leaving a urine trail (with specific scent compounds) or musth rumbling would attract the attention of receptive cows in the area.
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