Relocating one of two Auckland Zoo lions euthanised earlier this year was never an option due to potential welfare concerns and the state of 17-year-old Amira's health.
Nearly three months after Amira and her 19-year-old mother, Kura, were put to sleep, the zoo has confirmed a post-mortem showed Amira was suffering irreversible health issues that were likely to have caused fatal kidney failure in the near future.
The zoo made the heartwrenching decision to euthanise its two remaining lions in June. The pair have been widely mourned by staff and zoo regulars.
Kura had been struggling to maintain her weight, was showing signs she was feeling vulnerable - including acting submissively to her daughter - and her quality of life was drastically deteriorating.
Auckland Zoo has released a series of documents under the Official Information Act to the Herald on Sunday outlining the deep care shown to the lions in the months leading up to their death, and the steps taken prior to the decision to put them down - including assessing the option of relocating Amira.
In an email exhange, Auckland Zoo's curator of mammals Warren Spencer said he seriously doubted moving Amira was an option as other animals wouldn't tolerate her.
"When I say won't tolerate her I mean that it could result in a fatal injury," Spencer wrote in an email.
He said he felt the zoo had the necessary knowledge to make the decision without the advice of external carnivore specialist.
Leaving Amira living alone at Auckland Zoo was also ruled out.
"It would be unthinkable for us to consider keeping any single elderly lion here no matter the time we throw at this," Spencer said.
The curator later approached the Australasian species' co-ordinator for urgent advice on the "complicated situation".
"I can't think there will be anywhere for Amira to go to in the region at her age, plus I am not so sure she would do very well with the transport or being parted from Kura and all the massive amount of stress that these events would cause.
"I think I would prefer she goes with her mum," Spencer wrote.
The Australasian co-ordinator responded, saying there wasn't anywhere they knew for Amira to go as there were no lone males in the region.
The issue was discussed further over the phone.
Talking to the Herald on Sunday, Auckland Zoo director Kevin Buley said the species co-ordinator had a complete understanding of all rehoming options at all accredited zoos.
"Integrating adult female lions into an existing pride would have been stressful and dangerous for her and would have resulted in injury and potential death," Buley said.
The zoo's carnivore team leader, Lauren Booth, said of the decision to put the lions down: "We love both Amira and Kura and will miss them terribly, but we know that euthanising Amira enabled her to die peacefully with Kura, and not endure any unnecessary suffering."
Buley said lions were an incredibly important part of the zoo's future plans because of their power in connecting people with wildlife.
The zoo is part of an international breeding advocacy programme for the species.
Buley said in a few years the zoo will get a young breed group as part of the programme for this big cat, now listed as 'vulnerable' with a decreasing population.
"In the meantime, we have just welcomed two male lions from Wellington Zoo who will be staying with us for a period while we are without a pride."
The upper end of life expectancy for female lions in the wild was 15 years, and 17 years in zoos.