A Channel 4 documentary about the animals of Chester Zoo will return for a second series later this year.

The Secret Life of the Zoo was a huge hit for Channel 4 in its first series , averaging 2.7 million viewers per episode after giving an exclusive glimpse into some of the zoo’s 20,000 animals and their relationship with the 86 keepers.

The new series, which will include a Christmas special, promises to feature 'amazing' new stories – from the mating of rare spectacled bears to observing the nighttime behaviour of elephants, as well as finding out what’s become of babies born in the last series, such as infant elephant Nandita.

Related : Dinosaurs to return to Chester Zoo

Viewers will be taken inside a 'hidden world', using groundbreaking filming techniques to capture animal behaviour and relationships as never before, while allowing keepers to share their insights into the reality of caring for some of the world’s most endangered species.

Dr Mark Pilgrim , Chester Zoo’s director, said: “The Secret Life of The Zoo gives viewers a unique insight into the lives of our animals and throws a spotlight on the incredible passion and dedication of the keepers that care for them.

In pictures: The animals of Chester Zoo, by Dale Miles

"In series one it was thrilling to see the births of a Rothschild’s giraffe and an Asian elephant calf in such intimate detail but importantly it helped us to drum up some newfound appreciation for lesser known, critically endangered species such as mountain chicken frogs and Philippine cockatoos - and the work we are doing to try and conserve them.

"Modern, forward-thinking zoos can play a significant role in wildlife conservation and we’re pleased that, by taking viewers behind-the-scenes with us, we’ve helped to change a few perceptions. In series two we plan to delve even deeper.

"We care for more than 20,000 animals – from the weird to the wonderful – so there are plenty more remarkable species for viewers to get to know.”