An aging lioness has been put down at Adelaide Zoo amid fears she would be too heartbroken to join another pride following the death of her partner.
Amani, the oldest lioness in Australia at 23, was euthanised on Thursday, the zoo said on social media.
It followed the death of her partner, Mujambi, who had suffered a medical episode at the weekend.
"Despite the best care by our veterinary team, the difficult decision was made for him to be humanely euthanised," the zoo said in a Facebook post.
"Amani was then put to sleep shortly after as the negative welfare and aspects of her life without Mujambi were determined to outweigh any positives of remaining alone."
The zoo's director, Phil Ainsley, said lions were a social species and Amani's specific behaviour had been considered before making the difficult decision.
"The likelihood of safely moving or integrating Amani into another pride or environment was considered too risky and stress-provoking," he said.
Amani and Mujambi, who was 19 with a beautiful but thinning black mane due to his age, were closely bonded.
"She swiped at him, growled and bossed him around, but she also wanted to be no further away from him than his shadow," zoo curator Deb Barry said.
Ms Barry said Amani was a fierce lioness and she "would snarl, pounce and rip at her meat".
"While she was the dominant of the two, she sought out Mujambi as if it was her role to keep a watchful eye on him," she said.
"She'd regularly tell him off but in her next breath cosy up alongside him."
African Lions live to about 15 years of age in the wild but under human care in a zoo or safari park, can live into their twenties.
"Our keepers are extremely sad," Ms Barry said.
"They've spent years caring for Amani and Mujambi."