Early life care shapes African elephants' future
An African elephants mother's ability to feed and care for its calf has "long-lasting consequences" into adulthood, a study has suggested.
Researchers identified a link between the quality of maternal care in the first two years of a calf's life and reduced growth and delayed maturity.
They added that projected climate change and habitat loss could have a profound impact on the species.
Details of the findings appear in the journal Biology Letters.
"Early maternal care in the first two years of life actually affects an elephant's survival over 40 years - it has long lasting consequences," explained co-author Phyllis Lee from the University of Stirling.
"It is a problem we tend to overlook, unless we are looking at humans: how animals respond over the very long-term to apparently small events that happen in their lives."
Prof Lee and colleague in the international team of researchers said inexperienced mums often provided "inappropriate care".
"Often, they are not only inexperienced but if an elephant gives birth aged 10-12, she's tiny so she does not have the physical resources to devote to the calf.
"That has immediate consequences in that the babies are more likely to die, but those babies that do survive then tend to be put at a disadvantage, especially sons, for the rest of their lives."
These disadvantages included delayed sexual and physical development.
In detail: African elephants
- The IUCN Red List of Threatened Species lists African Elephants as Vulnerable
- Genetic research suggests that African elephants could actually consist of at least two species
- The species is found in in 37 countries in sub-Saharan Africa
- The main threats facing the continent's elephants are considered to be poaching (for meat and ivory) and habitat fragmentation
- Elephants are unusual among mammals in that they continue to grow throughout their life, although the rate slows after they reach sexual maturity
- Average length: 6.0-7.5m (males); 5.4-6.9m (females)
- Average height: 3.3m (males); 2.7m (females)
- Average weight: Six tonnes (males); three tonnes (females)
(Source: IUCN Red List; ARKive)
"It is particularly true for the males, which grow up to be shorter-than-average adults," Prof Lee told BBC News.
"As a result, they delay coming into a reproductive state, which is called musth, and as they are never going to be quite as big as their age-mates, they may always be at a reproductive disadvantage.
"If you lose a number of years of your reproductive potential because your lifespan is not that long, that could cut your reproductive success dramatically."
Musth refers to a period when bull elephants' temporal glands become swollen, from which a strong smelling fluid, rich in testosterone, runs down on their cheeks. During musth, males become very aggressive and sexual active.
She explained that female African elephants (Loxodonta africana) are able to give birth from about 10-12 years but males did not reach sexual maturity until the age of 25-30 years.
"The reason it is so late is because the physiological costs of the reproductive state are so high that they really have to be big, strong and tough to enter musth."
However, Prof Lee explained that the well-documented tight social bonds that elephants form with other individuals in the group did provide exceptions to the rule.
"What we think happens is that the ones that do have good survival in early life is because they either have a mother present in the group or they have a very knowledgeable matriarch," she said.
"Those are two key factors that help a first-time mum's baby survive - inexperienced mums that have a mother or grandmother in the group are much better off than inexperienced mums without social support.
Prof Lee added that human-induced pressures, such as hunting, along with projected climate change and habitat loss, have the potential to change the dynamics of elephant populations and, jeopardise the long-term future of the species.
"In the absence of human-induced mortality, you still have consequences of anthropogenic changes in the environment," she suggested.
"This means that the more droughts we suffer, the more difficulty that first-time mothers have rearing their babies with no social support so we could see a greater propensity to lose animals over their lifespan.
"This will change the group composition, you change knowledge structures, you change the social support, and you change the survival of every individual in those closely-knit groups."