Musth
Adult males enter a state of increased testosterone known as musth. In a population in southern India, males first enter musth at the age of 15, but it is not very intense until they are older than 25. At Amboseli, bulls under 24 do not go into musth, while half of those aged 25–35 and all those over 35 do. Young bulls appear to enter musth during the dry season (January–May), while older bulls go through it during the wet season (June–December).
The main characteristic of a bull’s musth is a fluid secreted from the temporal gland that runs down the side of his face. He may urinate with his penis still in his sheath, which causes the urine to spray on his hind legs.
Behaviours associated with musth include walking with the head held high and swinging, picking at the ground with the tusks, marking, rumbling and waving only one ear at a time. This can last from a day to four months.
Males become extremely aggressive during musth. Size is the determining factor in agonistic encounters when the individuals have the same condition. In contests between musth and non-musth individuals, musth bulls win the majority of the time, even when the non-musth bull is larger.
A male may stop showing signs of musth when he encounters a musth male of higher rank. Those of equal rank tend to avoid each other. Agonistic encounters typically consist of threat displays, chases, and minor sparring with the tusks. Serious fights are rare.
Mating of Elephant
Elephants are polygynous breeders, and copulations are most frequent during the peak of the wet season. A cow in oestrus releases chemical signals in her urine and vaginal secretions to signal her readiness to mate.
A bull will follow a potential mate and assess her condition with the flehmen response, which requires the male to collect a chemical sample with his trunk and bring it to the vomeronasal organ.
The oestrous cycle of a cow lasts 14–16 weeks with a 4–6-week follicular phase and an 8- to 10-week luteal phase. While most mammals have one surge of luteinizing hormone during the follicular phase, elephants have two.
The first (or anovulatory) surge, could signal to males that the female is in oestrus by changing her scent, but ovulation does not occur until the second (or ovulatory) surge. Fertility rates in cows decline around 45–50 years of age.
Bulls engage in a behavior known as mate-guarding, where they follow oestrous females and defend them from other males. Most mate-guarding is done by musth males, and females actively seek to be guarded by them, particularly older ones.
Thus these bulls have more reproductive success. Musth appears to signal to females the condition of the male, as weak or injured males do not have normal musths.
For young females, the approach of an older bull can be intimidating, so her relatives stay nearby to provide support and reassurance During copulation, the male lays his trunk over the female’s back. The penis is very mobile, being able to move independently of the pelvis.
Prior to mounting, it curves forward and upward. Copulation lasts about 45 seconds and does not involve pelvic thrusting or ejaculatory pause. Elephant sperm must swim close to 2 m (6.6 ft.) to reach the egg.
By comparison, human sperm has to swim around only 76.2 mm (3.00 in).
Homosexual behavior is frequent in both sexes. As in heterosexual interactions, this involves mounting.
Male elephants sometimes stimulate each other by playfighting and “championships” may form between old bulls and younger males.
Female same-sex behaviors have been documented only in captivity where they are known to masturbate one another with their trunks.
Birth and development By Elephant
Gestation in elephants typically lasts around two years with interbirth intervals usually lasting four to five years. Births tend to take place during the wet season. Calves are born 85 cm (33 in) tall and weigh around 120 kg (260 lb).
Typically, only a single young is born, but twins sometimes occur. The relatively long pregnancy is maintained by five corpus luteums (as opposed to one in most mammals) and gives the foetus more time to develop, particularly the brain and trunk.
As such, newborn elephants are precocial and quickly stand and walk to follow their mother and family herd. A new calf is usually the center of attention for herd members. Adults and most of the other young will gather around the newborn, touching and caressing it with their trunks.
For the first few days, the mother is intolerant of other herd members near her young. Alloparenting – where a calf is cared for by someone other than its mother – takes place in some family groups. Allomothers are typically two to twelve years old.
For the first few days, the newborn is unsteady on its feet, and needs the support of its mother. It relies on touch, smell, and hearing, as its eyesight is poor. It has little precise control over its trunk, which wiggles around and may cause it to trip.
By its second week of life, the calf can walk more firmly and has more control over its trunk. After its first month, a calf can pick up, hold, and put objects in its mouth, but cannot suck water through the trunk and must drink directly through the mouth. It is still dependent on its mother and keeps close to her.
For its first three months, a calf relies entirely on milk from its mother for nutrition, after which it begins to forage for vegetation and can use its trunk to collect water. At the same time, improvements in lip and leg coordination occur.
Calves continue to suckle at the same rate as before until their sixth month, after which they become more independent when feeding. By nine months, mouth, trunk and foot coordination is perfected. After a year, a calf’s abilities to groom, drink, and feed itself are fully developed.
It still needs its mother for nutrition and protection from predators for at least another year. Suckling bouts tend to last 2–4 min/hr for a calf younger than a year and it continues to suckle until it reaches three years of age or older. Suckling after two years may serve to maintain growth rate, body condition and reproductive ability.
Play behavior in calves differs between the sexes; females run or chase each other while males play-fight. The former are sexually mature by the age of nine years while the latter become mature around 14–15 years.
Adulthood starts at about 18 years of age in both sexes. Elephants have long lifespans, reaching 60–70 years of age. Lin Wang, a captive male Asian elephant, lived for 86 years.