When Cynthia Moss first began watching Echo in 1973, the herd numbered only seven individuals. Twenty years on and the E family herd had doubled in size under Echo's wise leadership.
Echo had given birth to at least five calves before, and new arrival Ely is greeted with no less curiosity by the herd. However, Echo's new youngster was clearly having problems and appeared unable to straighten his legs and walk. This clip gave a glimpse into Echo’s caring nature. Other elephants might have abandoned the baby.
Echo and Enid move around slowly in Ely's early days, allowing him to crawl along on bent legs and keep up. Early signs of some flexibility in his limbs give a glimmer of hope that the youngster might overcome his problems. Although bonding with the herd is another matter!
Driven by the desperate effects of drought, Echo finally makes the decision to travel to a new area. On the way, they visit the 'grave' of Emily, once Echo's closest companion. It's hard to know what awareness of death elephants have, but there's clearly something going on in their minds.
Three years after the first programme introduced them, the E herd make a second screen appearance. Echo is now a grand old matriarch, head of a herd of 15 individuals which includes a new generation.
January 1994 and there are more changes in the E herd. Young male Eric has left the group and Echo is looking tired and heavy. No wonder, she is 18 months pregnant, having been mated by Beachball who made a brief appearance in the first programme when he beat single-tusked Lexie in a dominance challenge. With such parentage, the new youngster should be a champion.
After 21 months of pregnancy, the delivery time of Echo's eighth calf arrives. Will everything go more smoothly than Echo's last birth when poor Ely had such a difficult start? The herd gathers and trumpets their delight at the new arrival, but there are dangers lurking in the darkness.
After an exhilarating night in which Echo gave birth to a new calf, Ebony, it's time to move the family on so they can refresh themselves. Echo heads for an unlikely spot - the swamp - carefully navigating the soft muddy earth and the deep pools to lead the herd, and her tiny calf, to safe grazing.
Echo's new calf, Ebony, turns out to be utterly fearless and is always getting into scrapes and venturing off to explore. Things go awry when she finds herself the centre of attention in another herd, whose matriarch refuses to return the youngster to her mother. In an amazing display of planning and teamwork, Echo and the other big females plough into the kidnappers to rescue Ebony.
By 2000, and four years since her last screen appearance, Echo should finally have shown signs of reaching old age. But she's still fighting fit and now presides over an impressive family of 26 individuals, including a new grandson Emilio.
Echo shows intense loyalty to her ailing daughter Erin, whose injury is getting the better of her. She sticks close by her, never more than a few kilometers away and constantly rumbling to communicate with her suffering daughter. Finally, she makes the decision to take Email away and leave Erin in peace. Her suffering comes to an end when the research team calls in the vets to put her to sleep.
At the end of the third programme, the herd is in good shape. Six months after the death of his mother, Email has become the youngest male orphan to survive the death of its mother. Though Echo is now probably in her late 50s, she's still attracting male attention and may yet have another calf to introduce a new chapter to her eventful life.
On 3rd May 2009, an aging Echo succumbed to the ravages of drought and old age and died. She had collapsed the day before and been unable to get up again. One of the research team was with her when she died. Leaving the herd without a leader in such difficult conditions would make their survival even tougher. Had they learned enough from Echo to be able to cope without her and to be able to find food and water in the worst drought in living memory?
After three years of increasing dry spells, the rain arrives bringing an end to Amboseli's worst drought in living memory. And even without Echo at the helm, not one of the family members has died - truly a remarkable achievement.
Researcher Cynthia Moss visits Echo's body which still remains recognisable on the savanna. It's hard to connect the carcass with the vibrant personality that Cynthia has known so well, but Echo's legacy has been imprinted so strongly on the E family, it will endure throughout generations to come.
1945 - 2009
Echo has been a much-loved character on our screens since David Attenborough first went to film her in Kenya in the early 1990s. Researcher Cynthia Moss and her Maasai colleagues at the Amboseli Trust for Elephants had been following the park's elephants for many years and were intimately acquainted with Echo's family which was one of 58 family groups in the area.
Since first following her in 1973, the researchers had seen repeated evidence of Echo's intelligence and leadership. Through the next 37 years of daily observations they came to know her intimately. Echo was first filmed in the early 1990s for the Natural World by which time - aged 45 - she had become the matriarch of the E Herd.
Over the next 20 years, Echo guided her steadily-growing family through feast and famine and her story was told in two more films. Her death in 2009 couldn't have come at a worse time for the herd as they suffered the effects of the worst drought conditions in living memory. A final programme explores whether the E herd can survive such hardship without Echo's wisdom and guidance.
Follow the story of an extraordinary elephant through video clips of her life's major events from all four programmes.
Learn more and watch video from BBC archive