LONDON — Staff members at London Zoo were “heartbroken” after a high-risk matchmaking operation involving two rare Sumatran tigers went horribly wrong on Friday. The male’s deadly mauling of the female tiger soon after they met drew an outpouring of reactions on social media.
But one question was paramount: Could the tragedy have been avoided?
The animals had been paired as possible mates as part of a European-wide conservation effort for the critically endangered subspecies. Asim — age 7, confident, handsome, playful — had been shipped in from Demark to meet Melati, a fellow Sumatran who had lived for years at the renowned zoo in Regent’s Park in Central London.
He courted her for 10 days in a separate enclosure, the zoo said — “chuffing” at her and getting used to her sight and scent. Then he finally approached her.
Melati, who had raised five cubs with another tiger, never survived the encounter. She died at 10 years old.
Shocked and grieving social media users questioned London Zoo’s methods:
Was it too soon for the two wildcats to meet?
Why didn’t keepers use tranquilizers when the encounter turned violent?
And why not use other methods, such as reproductive biotechnologies, to try to increase the population of a subspecies whose numbers have shrunk in the wild?
“This death is on you,” Gal Hazor, a pop culture writer, said in a tweet on Saturday. “You brought a tiger to an unnatural environment, and introduced him to another tiger less than two weeks later.”
Helen Goss, a social media manager, also wrote on Twitter: “Why on Earth would you introduce two tigers after only 10 days!?”
“I wouldn’t introduce my cat to a new cat in such a short time,” she added, calling the approach “unbelievable” and “cruel.”
The zoo said in a statement on Friday that it had taken every precaution before the pairing, and that experts had judged the time right for the introduction.
Staff members also tried to save Melati when things turned aggressive, the zoo said, but it was too late.
“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 statement said.
Some came to the zoo’s defense.
Vivian Walker, a wildlife photographer and conservation worker, argued that “every meeting between big cats is a risk no matter how calculated,” and that tranquilizers “would not have taken effect quick enough to save her.”
In fact, in an updated statement, the zoo said, “A tranquilizer would not have been effective, not only because of the difficulty of targeting the correct tiger in that situation, but due to the length of time needed for it to take effect.”
Others questioned if a safer method to help Melati produce more cubs could have been used.
“Wouldn’t artificial insemination have been the safer way to go?” Barbara Gould Stringer wrote on Facebook.
Rebecca Blanchard, a spokeswoman for the Zoological Society of London, which manages London Zoo, said in an email on Sunday that the vets at the zoo had pioneered artificial insemination for its animals a decade ago, when traditional mating had not been successful for a pair of tigers.
But the method “was not required in this instance,” she said, “as there was a suitable male and female who could be paired.”
Artificial insemination, the process of collecting sperm from a male animal and manually depositing it into a female’s reproductive tract, has been used successfully before to facilitate the reproduction of endangered tiger species.
In the United States, there have been three known tiger pregnancies from artificial insemination in the past 20 years, according to the Minnesota Zoo, which coordinates a Tiger Species Survival Plan. But the success rate has been low so far.
“The limited contribution of fertility preservation techniques to species conservation principally stems from the lack of knowledge of species biology, as well as inadequate facilities, space, expertise and funding needed for their successful application,” Pierre Comizzoli, a research biologist at the Smithsonian Conservation Biology Institute, wrote in a paper published in January 2015.
Mr. Comizzoli argued that, before developing assisted reproductive techniques, knowledge of reproductive traits is first needed. “Unfortunately, we know very little about species biology (reproduction in only 250 species has been properly described),” he wrote.
In fact, Melati mated with another Sumatran tiger, Jae Jae, in 2013, 2014 and 2016 to produce her cubs. But Jae Jae was recently moved to Le Parc des Félins, a zoo southeast of Paris, in order to start a new family.
“The European breeding program takes lots of factors into consideration — including parentage and history, to generate the most genetically diverse population possible,” Ms. Blanchard wrote.
Jo Cook, who coordinates the London Zoo’s Sumatran tiger breeding program, said in a statement in late January: “With just 400 critically endangered Sumatran tigers remaining in the wild, it’s important that tigers like Jae Jae 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.”
Sumatran tigers are the smallest surviving tiger subspecies. Known scientifically as Panthera tigris sumatrae, they weigh 165 to 380 pounds, are distinguished by their orange coats and black stripes and can be found in the wild only on Sumatra, an Indonesian island.
There are fewer than 400 of the rare tigers left, according to World Wildlife Fund, an international nongovernmental organization. The animals’ low numbers render their reproduction critical for their survival.
It is still not clear why Asim attacked, and many are mourning the loss of a treasured animal.
The zoo said that Asim had sustained a “minor injury” from the attack Friday and was being treated by vets.
It is also unclear if London Zoo will use him to mate again.