There were lots of reasons to celebrate Chester Zoo this year, not least the amount of animal births, some of which include the world’s rarest species.

Zoo staff say that a combination of factors, including detailed planning, highly knowledgeable keepers, great infrastructure, a compressive animal nutrition plan, top husbandry techniques and scientific insight to back it all up, have all contributed to the baby boom.

Here are the top 10 zoo births of 2015:

1. Siska the Sumatran orangutan

Siska the Sumatran orangutan

Tiny Sumatran orangutan Siska was spotted in her mum’s arms by zookeepers doing their daily morning checks in September.

Tim Rowlands, curator of mammals at the zoo, said: “It was fabulous to come in and see a tiny pair of arms clinging to her mum, Subis. Subis is an excellent, very experienced mum and she’s doing a brilliant job of caring for little Siska.”

“Subis herself was born here in 1986 and has since had four other young, but she was the first Sumatran orangutan to be born here at the zoo in just under three years.”

Sumatran orangutans are listed as critically endangered by the International Union for the Conservation of Nature (IUCN) and face an extremely high risk of extinction in the wild. It’s estimated that less than 6,500 now remain due to the destruction of habitat for logging and the wholesale conversion of forest land to palm oil plantations.

2. Nandita the Asian elephant

Nandita, an endangered species of elephant, was born surrounded by relatives at Chester Zoo

A rare Asian elephant calf, which keepers named Nandita, was born in August. Nandita’s birth was caught on CCTV cameras at the zoo, which showed amazing footage of her getting up to her feet within three minutes of being born with encouragement from her mum, Thi Hi Way.

Andy Mckenzie, team manager of elephants, said: “The birth of a new elephant is a real family occasion and, as the labour progresses, all of the family unit really come together. They all knew that something was going to happen, especially the older elephants that have seen it all before. Thi is an experienced mum and the birth went very smoothly indeed.

“As soon as the calf was born onto the soft sand, the family started to lean down to have a look. Not long after, she was up and standing on her feet.”

Earlier in the year, 12 members of zoo staff flew to Assam in India to work on a project which is helping protect wild elephants and the people who live with them. The zoo now hopes that Nandita can help raise more awareness of the endangered species.

3. Sumatran tiger triplets, Topan, Jaya and Kasarna

Sumatran tiger triplets, Topan, Jaya and Kasarna

In January, three rare tiger triplets were born to eight-year-old Sumatran tigress Kirana and dad, Fabi.The trio, two boys and girl, were named Topan, Jaya and Kasarna.

Tim Rowlands, said: “Sumatran tigers are one of the rarest big cat species in the world and that’s what makes our tiger trio so incredibly special - they’re a rare boost to an animal that’s critically endangered.

“Topan, Jaya and Kasarna are part of a safety-net population in case the species becomes extinct in the wild. That to me is incredibly humbling.”

Sumatran tigers can only be found on the Indonesian island of Sumatra and are the smallest of all tigers and also have the narrowest stripes.

4. White-winged ducklings

White-winged ducklings

The arrival of two incredibly rare white-winged ducklings in June gave a huge boost to the endangered species.

Experts fear that just 250 could now remain in the wild as a result of widespread destruction to their habitats throughout South East Asia, where they were once found in abundance.

Andrew Owen, curator of birds, said: “This species of duck is on the edge of extinction and the ducklings will contribute hugely to the European breeding programme, ensuring that zoos have an insurance population if these birds are lost completely in the wild.

“Our field programmes team is also working very hard over in South East Asia to try and preserve the areas in which this, and many other bird species, can be found so that they all have a better chance of survival.”

5. Rare cinnamon frogs bred in ‘UK first’

Rare cinnamon frogs born at Chester Zoo

Zookeepers announced the UK first breeding of a rare frog species in January. Forty-three cinnamon frogs arrived after amphibian experts at the zoo recreated conditions to mimic the tropical forests of Borneo and Sumatra, where the species come from.

Ben Baker, team manager of lower vertebrates and invertebrates, said: “Cinnamon frogs are a secretive species and live in a very, very specialised environment. Their ideal habitat is incredibly limited and so, as with many frog species around the world, they are extremely fragile.

“Currently they are listed as near threatened by the International Union for the Conservation of Nature (IUCN) but with population sizes decreasing due to widespread habitat loss, the species is likely to become threatened in the near future.”

Although relatively little is known about the cinnamon frog, the delicate work the zoo’s team has put into getting the beautiful but complex animals to breed, plus all of the intensive care they’re now giving them, will be invaluable for the long-term protection of the species.

6. Not one, not two… but three onager foals.

Three onager foals born at Chester Zoo

Keepers celebrated the arrivals of three exceptionally rare onagers, born only weeks apart.

Two of the foals arrived on the same day to respective mums Zarrin and Jamila and were soon followed by Apple who gave birth to a third foal only a few weeks later.

Tim Rowlands said: “Onagers are the rarest equid species in the world and one of the rarest animals that we have here at the zoo, so we were absolutely delighted to have three foals arrive in such a short space of time.

“With so few remaining in the wild, a successful conservation breeding programme in zoos is hugely important if we’re to stop these animals from going extinct.”

The onager was once found in abundance across the deserts of Mongolia, China and Iran. Now, the species is listed as critically endangered by the International Union for the Conservation of Nature (IUCN) and research suggests that only 600 are left in the wild.

7. Kidepo the Rothschild’s giraffe calf

Rare Rothschild's giraffe calf Kidepo, was born at Chester Zoo in 2015

A rare Rothschild’s giraffe calf, a male named Kidepo, was born on 23 July - the second of his species to be born at the zoo in 2015 and the third in the space of just eight months.

The new additions, classed as endangered by the International Union for the Conservation of Nature (IUCN), have given an important boost to the ongoing breeding programme for the species. Recent estimates suggest that fewer than 1,100 are left in the wild – making them one of the most endangered subspecies of giraffe in the world.

Dr Nick Davis, assistant curator of mammals, said: “If our new arrivals can help to raise awareness of the huge pressures that Rothschild’s giraffes face on a day-to-day basis out in the wild and highlight the ever-growing need for conservation, then we’ll be very happy indeed.”

The zoo also supports vital projects in the wild - including the first ever scientific review of the species - with the aim of developing a long-term conservation strategy for the animals in Africa.

8. Baer’s pochard ducklings

Baer's pochard ducklings

Twenty-four Baer’s pochard ducklings – one of the world’s rarest species - hatched in May, giving a much needed boost to the global population.

Andrew Owen said: “This extremely rare species of duck is on the very edge of extinction, so the new arrivals will make a vital difference to their ever-decreasing population numbers. We’re working really hard with zoos in the UK and across Europe, as part of a breeding programme, to ensure that we have a viable captive population if their numbers continue to decline.”

Baer’s pochard are listed by the International Union for the Conservation Nature (IUCN) as critically endangered and research has shown that, where the ducks where once where found in large numbers, they have now completely disappeared.

9. Okapi calf, Usala

Okapi calf Usala was born in May

A rare okapi – an unusual African animal that is the closest-living relative of the giraffe - was born in May.

The male calf, who keepers named Usala, arrived to mum Stuma after a 14-and-a-half-month-long pregnancy. With only 14 okapis in zoos in the UK, Usala’s birth gave an important boost to the breeding programme for the endangered animals which, in their native Democratic Republic of Congo (DRC), are declining due to habitat loss and hunting for their meat.

Tim Rowlands said: “The okapi is going through a silent extinction. It’s a species that continues to be forgotten and we need to start sticking our necks out for them. Hopefully the arrival of Usala can really draw some much needed attention to these incredibly beautiful animals.”

Chester Zoo works with the International Union for the Conservation of Nature’s (IUCN’s) giraffe and okapi specialist advisory group to develop a conservation strategy for okapis and also supports the DRC Wildlife Authority and their efforts to protect the species in the Ituri Forest in the DRC.

10. Female Brazilian tapir

The female tapir calf was born on December 5

Earlier this month, keepers announced the arrival of a rare Brazilian tapir – born on December 5. The female calf, which has not yet been named, was born to experienced parents Jenny and Cuzco.

Young tapirs are born with spots and stripes all over their bodies, heads and legs but lose these patterns in the first year of their life.

“With her brown coat currently covered in white stripes and spots, our new tapir calf resembles a little humbug on legs at the moment,” said Tim Rowlands. “Lowland tapirs lose this patterning over time but, for a newborn, it’s a great form of camouflage on the forest floor.

“We hope that our new arrival will be another great ambassador for the species and their cousins in the wild who, sadly, fall victim to a number of devastating threats that has resulted in a huge loss of wildlife across South America.”

Chester Zoo supports conservation projects in Brazil that are researching the different behaviour patterns and movements of tapirs in the wild and hope to play a major role in safeguarding the species for future generations.There were lots of reasons to celebrate Chester Zoo this year, not least the amount of animal births, some of which include the world’s rarest species.

Zoo staff say that a combination of factors, including detailed planning, highly knowledgeable keepers, great infrastructure, a compressive animal nutrition plan, top husbandry techniques and scientific insight to back it all up, have all contributed to the baby boom.