Elephants are extremely long-lived mammals; longevity, experience and reproductive success go hand in hand. Older matriarchs act as a repository of social and ecological knowledge, thereby influencing the reproductive success and survival of their family members, while older males are the primary breeders.
We damage the fabric of elephant society when we remove older individuals; our management of wild elephants must reflect the importance of older males and females in maintaining the integrity of elephant society.
- Elephants are long-lived mammals, especially for the ungulate group. In the wild elephants may survive to 70 years of age. In captivity the highest authentic age is 79 although this is exceptional.
- The age of first birth varies across populations, ranging from 7 to 22 years of age, with most females giving birth for the first time between 14 and 15 years old in African elephants, and slightly later for Asian elephants. Fecundity is fairly constant between the ages of 16 and 40 and then declines slightly, though females over 60 can still give birth.
- Males reach sexual maturity by about age 15-17, but due to their relatively small size and inexperience they do not sire significant numbers of offspring until they are over 25-30 years old, and only attain consistent access to estrous females when they are close to 40 years old. Peak reproductive success for males is attained between 40 and 50 years of age. Males are still reproductively active at age 60, siring as many calves as a 40-year-old male.
- Mortality varies from population to population depending upon such environmental factors as the level of human induced deaths, and drought.
- Calf mortality can be as high as 25% or as low as 5% in the first year of life, depending upon human and environmental pressures.
- The longest demographic study of African elephants, in Amboseli Kenya, shows that males have higher mortality than females throughout most of their lives. Life expectancy at birth is 41 years for females and 24 years for males. In the absence of human induced mortality, however, female life expectancy increases to 54 years and male life expectancy to 39 years.
- Increased body size, mass, condition and experience are associated with increasing male age; therefore longevity underlies both the maintenance of the musth strategy and the overall reproductive success of males.
- Longevity is the key to understanding elephant male reproductive strategies; males only begin to reproduce regularly by the age of 40, an age by which 75% of males have died. Older males in musth father three quarters of all calves.
- Elephants as individuals and as groups appear to comprehend the better judgement of older females; calves of young mothers spend significant time in the close company of their grandmothers, family members run to the oldest individual in times of real danger, and groups led by young matriarchs seek out families with older leaders with whom to associate.
- Advancing age among females is associated with increased social and ecological knowledge and discriminatory abilities. Consequently, the age and experience of a matriarch affects the survival and success of her entire family.