Elephant Baby Booms

by Prof. Phyllis Lee

Elephants, like many living organisms, reproduce at high rates when times are good. By “good”, biologists tend to mean that more energy is available than just that required for growing and living. Famously, lemmings, voles, and even fig trees all have periods when exceptional numbers of offspring are produced all at once in a baby boom. It makes sense for small creatures to produce as many babies as possible, for trees to invest abundant energy into fruits, or for the swamping of predators with mass production of offspring all at a single time. 

Elephants, despite their size and their twenty-two-month gestation period, can respond to energy abundance by increasing the rate at which individuals get pregnant, which results in elephant baby booms. In 1979, the first of the AERP’s baby booms was predicted by Cynthia. She noted that more than half the calves born in 1976 died in a severe drought and the females stopped reproductive cycling. When good conditions returned in 1977 there were many adult females available to conceive.  Twenty-two months later the baby boom of 1979 began. 

Two of the calves born in the 2020 baby boom: Eliot's son and grandson

We saw a similar birth peak in the late 1990s, and two birth surges in the 2000s. Some peaks clearly follow a drought-related drop in females conceiving due to poor condition, which several years later leads to a pulse in births. Other highs also follow an upsurge in the numbers of females maturing. When both factors coincide, then a huge number of calves can be produced. The 2012 birth surge (201 calves) followed a prolonged period of intense drought and deaths among calves. The largest boom so far occurred in 2020 with the birth of 258 calves. Now we are expecting even more calves in 2025. 

There was a very severe drought in 2022 and up to March 2023. Many calves died and again females stopped reproductive activity. In 2024 only 31 calves were born to more than 600 adult females. Among these females, there were more than 100 newly matured females who were unable to become pregnant in the drought years, so they remained ready to produce a calf as soon as conditions improved. And conditions did improve greatly with higher than average rainfall for the rest of 2023 and all through 2024, bringing up abundant and nutritious vegetation. The elephants recovered and it appears that many of the females are pregnant and thus we are expecting a another baby boom. 

Baby booms have been seen elsewhere in savannah elephants, such as Tarangire in Tanzania and Addo in South Africa. Baby booms (and busts) may be a regular feature of elephant life, and as such provide fascinating insights into elephant biology and population dynamics.

The Watchtower

The ATE and Big Life teams working together to promote human-elephant co-existence

In addition to repellents and lights, we’re testing a watchtower, combined with drone deployment. This method aims to detect elephants early and deter them before they break the fence. Each technique is strategically placed at known fence break hotspots, monitored by camera traps to observe how elephants interact around the deterrents. As this phase progresses, we are interested to see which methods perform best,  and ultimately, if any of these solutions can be scaled up to protect both elephants and the Amboseli community more effectively.

The History of the D Families - Updated

Part of the DB family today - Donna, Dorcas and Dahlia

The ‘D’ females and the families they make up have always been something of a mystery. In fact, the Ds have a history of doing things elephants are “not supposed to do".  In the beginning the Ds were thought to be one family. What was eventually designated the DA family was photographed on the very first day of the study on September 1, 1972. Two adult females were present: a large old matriarch whom we named Dorothy and a much younger female we called Dinah.  The next time this family was seen on August 4, 1973 there was a third adult female present and she was photographed and named Delia. Over the next few months other females were seen in association with the D females but always in a variety of odd combinations.  One female was seen only once and then disappeared. She is simply referred to as the "D" female.

It was not until 1974 that I had some idea of who belonged to the family.  It looked like this:                  

Dorothy                              

    3-4-year-old                            

    6-7-year-old female               

    Adolescent male ±10                 

Dinah                                             

    2-year-old male                          

Delia                                               

    Adolescent male ±12                  

 Deborah                                         

 Diana                                             

 Daphne                                          

 "D female"                                     

 Male—±15   

To read the full updated history Click Here

ATE News

We greatly appreciate all the donors who contributed during the past six months. Your support is very important to us. With it we can continue to follow the Amboseli elephant families and the independent males, learning more about them every year. We particularly want to thank four anonymous donors and the following: