Lioness sprouts a mane at age 18
Bridget the lioness was born at the Oklahoma City Zoo in 1999, and she lived a fairly typical zoo lion life for most of her first 18 years. Then she grew a mane.
“At first, you’re kind of like, well, that’s a little different,” said Jennifer D’Agostino, the zoo’s director of veterinary services. “Then it kind of kept going to the point where it was like, wow, it looks like she’s growing a mane. That’s not quite right.” Bridget’s behaviour had not changed. Her appetite remained healthy. She seemed unbothered by her new look, and her fellow lions, halfsister Tia and a younger male named Hubert, were similarly unfazed. But by November, the mane looked like a thick scarf, and the zoo decided to try to untangle the mystery of this bearded lady.
The likely explanation, D’Agostino said, was testosterone. An overproduction of that hormone is also implicated in the lush locks of wild maned lionesses in Botswana’s Okavango Delta, but the causes are not clear, lion expert Luke Hunter said. It could be that the sperm of the lionesses’ fathers was “slightly aberrant,” causing a disruption of the embryos, or that the lionesses’ mothers had abnormally high levels of male sex hormone during pregnancy, he said. Researchers who study the Botswana maned lionesses say they have never become pregnant, which can be a consequence of elevated testosterone.
“Both situations occur occasionally in humans and other mammals, but, of course, we are less likely to observe it in wild animals,” said Hunter, chief conservation officer for Panthera, a global wild cat conservation organization. “Whatever the cause, we know that while they are infertile, maned lionesses in the wild are otherwise perfectly capable of survival.”
The case of Bridget’s mane is different, however. She grew a mane in late middle age for a captive lion. D’Agostino said that suggests it is caused by a tumour of some sort, perhaps on her ovaries, adrenal gland or pituitary gland. The first investigative step would be a blood test to compare Bridget’s testosterone level with that of a mane-free lioness — in this case, with a stored sample from Tia, who also is 18.
So far, the zoo has drawn only enough blood to do routine bloodwork, which has come back normal, D’Agostino said. Caretakers plan to try again this week to get a sample for a hormone test. If the levels suggest a tumour, treatment could involve hormone supplements to suppress the testosterone, or surgery as a last resort, D’Agostino said.