Colleen Kinzley, Founding Member Tembo Preserve & Director of Animal Care, Conservation and Research Oakland Zoo
Territorial and courtship displays occur in a wide array of species. In some species, individual males have been observed to selectively favor particular behaviors and/or vocalizations, making them unique to that individual male. Male chimpanzees, for example, are known to have particular components of aggressive or territorial displays that they favor and perform more often or even to the exclusion of other display behaviors. Some have even been documented creating their own display behaviors or incorporating some unique part of their surroundings. Many song bird males create unique variations on their songs differentiating them from neighbors of the same species.
African elephants live in matriarchal societies where young males leave their family group in their early to mid-teens. During their late teens and twenties, they spend their social time in loosely formed bachelor groups. Elephants continue growing throughout their lives; males in their teens and twenties are considerably smaller than bulls in their thirties and above, so these younger males typically have little opportunity to breed. Males over 25 years of age engage in periods of sexual activity and sexual inactivity. Periods of sexual activity are simply defined as time spent with females groups. During these periods, males may or may not be found in the company of other males but are consistently seen with female family groups.
African elephants spend much of their time on the move, sometimes walking many kilometers between resources such as food, water, and shade over the course of a day or two. They are also a migratory species, sometimes moving hundreds of kilometers seasonally to take advantage of rain or other resources. For sexually active males, estrous females represent a scarce and mobile resource. Musth is a unique strategy developed by male elephants to increase their reproductive success.
Musth and Male Elephants
A bull is considered to be in a state of sexual inactivity when he is not keeping company with females. In this case, he may be solitary or in the company of other bulls. Alternatively, sexually active males may or may not be in a state of musth. During musth, some individual bulls display unique behavior or behavior patterns just as males of other species are found to exhibit unique behavioral displays.
Characteristics of Musth
Musth is a physiological and behavioral state resulting from highly elevated testosterone levels compared to non-musth sexually inactive bulls. Musth has two outward defining characteristics: urine dribbling and the secretion of glands located in the temporal region of the head. The rate of urine dribbling, characterized by constant seepage from the retracted penis, can be variable but any amount of urine dribbling indicates that a bull is in a state of musth . From a distance, bulls in heavy musth can most easily be identified by the shiny, dark appearance to the inside of their legs, caused by the constant urine spray on their legs,
The constant seepage of urine can result in a whitish to greenish film around the opening of the penis sheath. This urine build up on the legs and sheath results in a distinct pungent odor. Musth temporal gland secretions are thick, sticky, dark in color, and have a strong odor. A bull in heavy musth may have a wide, wet, stain running from the temporal gland down to the lower jaw. Older bulls may develop very swollen temporal glands filling in the normal indentation of the skull above the temporal gland and behind the eye. These swellings increase the size of the forehead making the bull look even larger.
Who Exhibits Musth?
The period of time in which males spend in musth lengthens as he ages and continues to grow in size age. Males may begin to show signs of musth in their mid-teens, but in these early years it may last only hours or days and the presence of a dominant male will likely inhibit musth in these younger bulls. The median age for the onset of musth is 29 years old. As males age they typically experience a longer musth period ranging from a median of 2 days for bulls 16-25years to 81 days for males 46-50 years old then declining to 54 days for males 51-60 years old. The consistency of musth periods also increases with age; for young males, their musth period is erratic, and opportunistic. They may be stimulated into musth by the presence of an estrous female then driven out of musth by the arrival of a musth male or other dominant males. As males mature, and depending on their ranking in the population, they will eventually establish a relatively predictable period of musth each year. The most dominant males in the population get the most optimal musth periods, typically during and immediately after the rainy seasons when the largest number of females come into estrous.
An older musth bull will out compete not only non-musth bulls but also younger musth bulls. In most observed matings, the bulls were over the age of 35 years and in musth. Recent genetic paternity analysis of a well –studied population confirms these observations with 74% (88/119) of the calves sired by musth bulls.
Musth is an energetically expensive condition and even the most dominant males in a population typically can only maintain musth for a few months. Musth bulls spend less time feeding, more time on the move, and more time chasing, or fighting with other males resulting in a loss of condition.
Female Elephants Choose Mates
Females demonstrate choice through their participation or lack thereof with a potential mate. Courtship begins with urine and genital testing; an attractive female is first followed then chased by a male suitor. Smaller and faster than most males, the female is able to out run the male if she does not chose to stand for breeding.
For females, it is advantageous to consort with musth males and they demonstrate a preference for musth males. For example, during the period of consortship with a musth male, the female is not harassed by multiple, often young, males who are also perusing her. In addition, a musth bull represents a fit male, as only older, healthy males come into musth. The increased levels of testosterone that are characteristic of the musth condition also increase the bull’s fertility by increasing his sperm count, increasing the probability of successful fertilization of the females eggs.
So for both males and females the phenomenon of musth represents an effective reproductive strategy… even if it is not suitable materials for a Hallmark Valentine’s card!