The arrival of extremely rare elephant twins, caught on camera for the first time, sets their mother an "almost impossible" challenge, according to Sir David Attenborough.
The natural historian, 95, gives the warning on the next episode of his documentary series Dynasties II - which continues with its second episode on Sunday (March 27).
Producers of the BBC show were thrilled when they discovered that Angelina - the female elephant they were following in Kenya's Amboseli National Park - had given birth to son Atlas and, four days later, daughter Alana.
The series' narrator, Attenborough, however explains that the arrival of the second calf will "irreversibly change the fortunes" of the family of elephants.
He says: "Having twins is so rare that it's only been recorded five times in Kenya. Although this might seem like very good news for the future strength of the family, calves need so much milk and care that raising twins is almost impossible."
The broadcaster and author adds: "There's now a very real chance that Angelina could end up losing both babies."
The family has recently suffered the death of its matriarch and has lost 10 calves in five years.
The twins, unaware of the burden they create by needing 10 litres of milk each per day, spend their days playing with sticks and goading buffalo.
The upcoming episode contains heartbreaking scenes of the young elephants facing a life-or-death struggle to get out of a swamp.
They also come close to starvation when Angelina's milk dries up. And at one point Atlas is so exhausted, he needs help to lift his head.
Other dangers they face include the aggression of testosterone-fuelled bull elephants, drought and predators.
Series producer Simon Blakeney said: "We were very lucky to be able to be with the right female who gave birth to these two incredible little calves, a boy and a girl."
He added: "Instantly, that more than doubles the challenge that that female and her family face in bringing them up." But he said the elephants' cooperative nature gave the twins the best chance.
Viewers will see the family go to extraordinary lengths to keep them alive. Simon added: "When young are born into a group, they will physically all work together to bring them up.
"So while Angelina, the mum of these two calves, was the one leading their lives, she had help from their cousins, sisters and other members of the family."
Dynasties II continues on Sunday night at 8pm on BBC One.
Do you have a story to sell? Get in touch with us at webcelebs@mirror.co.uk or call us direct 0207 29 33033.
