Other \"unique\" cases in which female lions have developed a mane include a 13-year-old lioness at the National Zoo in South Africa in 2013, who had an issue with her ovaries that caused an excess production of testosterone.

In 2014, a group of five lionesses in the Botswana wildness were observed with manes. In that case, researchers believe a genetic component played a role, since the lions came from the same pride and developed the manes at a young age, according to the Oklahoma City Zoo.

While Bridget's veterinarians suspect hormones may play a role, that would also be the first factor to be ruled out once they get the results of the blood work, Cole said. Another culprit could be a benign tumor located on her adrenal or pituitary glands, which regulate hormones, the zoo said.

Bridget's age places her in the \"geriatric\" category of lions, Cole aid. The median lifespan for lions is 16.9 years, according to the Association of Zoos and Aquariums.

\"PHOTO:
Oklahoma City Zoo
PHOTO: An 18-year-old African lioness named Bridget is puzzling zoologists after she mysteriously sprouted a mane.
>

Bridget doesn't seem to notice her new hairdo and is acting \"completely normal,\" Cole aid. She's eating and grooming the same, and, more notably, her \"strong attitude\" is still present.

\"It's only the outward appearance of the mane that has changed,\" she said. \"... We are trying to solve the puzzle.\"

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