An endangered Sumatran tiger was mauled to death at London Zoo on Friday, just moments after it was introduced to a potential mate for the first time.
Melati, a female tiger and long-term resident of the zoo, was introduced to a new male tiger, Asim, on Friday in the hope the pair would breed in the future.
Keepers were devastated, however, when Asim, a 7-year-old male that had arrived at the London Zoo (ZSL) just 10 days earlier, fatally attacked Melati.
"Everyone at ZSL London Zoo is devastated by the loss of Melati, and we are heartbroken by this turn of events," the zoo said in a statement.
"Asim was moved to ZSL London Zoo as part of the European-wide conservative breeding program, and it was hoped that the two tigers would be able to breed in the future."
The two tigers were initially kept in separate, adjoining enclosures, where keepers allowed the two animals to "smell and react to each other."
The zoo acknowledged that while introductions of big cats are always considered "high risk," experts had observed "positive signs" and deemed it to be the "right time" to introduce the pair.
The keepers reported that the introduction of the pair started as "predicted," but it descended quickly into a "more aggressive interaction."
"Zoo staff immediately implemented their prepared response, using loud noises, flares and alarms to try and distract the pair, but Asim had already overpowered Melati," the zoo said.
Trained staff eventually managed to secure Asim in a separate paddock in order for vets to safely attend to Melati, but they confirmed that she had died in the attack.
Conservationists expressed sadness following the death of Melati, as Sumatran tigers are deemed critically endangered by the World Wildlife Fund for Nature. It is estimated that less than 400 of the species remain in the wild today.
Will Travers, president of Born Free Foundation, a charity supporting endangered wildlife, wrote on Twitter: "Only 400 left in the wild ... is captivity viable?"
In another post, he said: "After the tragic death of Melati, the tiger at London Zoo, let's step up and help keep wildlife in the wild."
London Zoo describes Sumatran tigers as the "rarest and smallest subspecies of tigers" in the world, and are native to the Indonesian island of Sumatra.
Asim was matched with Melati as part of the European Endangered Species Programme (EEP), and was transferred from Ree Park Safari in Denmark on January 29.
Zookeepers at London Zoo described Asim as a "handsome confident cat who is known for being very affectionate with the ladies," before his arrival in London.
Speaking before Asim's arrival, Jo Cook, the coordinator of the EEP program at ZSL, had stressed the importance of the tiger transfers.
"With just 400 critically endangered Sumtran tigers remaining in the wild, it's important that tigers like Jae Jae (the zoo's former male tiger) and Melati are given the opportunity to have cubs with other mates -- to ensure genetic diversity across the world's zoos and ultimately safeguard the future of the species," she said in a statement.