When an 18-year-old lioness named Bridget started sporting a noticeably furrier look in 2017, Oklahoma City Zoo (OKC) officials began to worry. After all, it’s not every day you see a female lion grow a mane. Now, scientists believe they’ve cracked the "Curious Case of Bridget’s Mane”.
When news of Bridget's masculine hairdo first broke, people of the Internet obviously had a few things to say about it.
Zookeepers took a different approach. They used behavioral training to coach Bridget into letting them draw a blood sample from her tail, eliminating the need for anesthesia. They then took a serum sample from her sister Tia to serve as a control to compare the pair’s hormone levels. Both of the lions were born at the OKC Zoo’s Lion Overlook in 1999. Both blood samples were sent to the veterinary school laboratory at the University of Tennessee for analysis.
Veterinary staff expected to find elevated testosterone levels like those found in one group of lions in the Okavango Delta in Botswana. Here, at least five females were found to have not only grown manes but to display male-associated behaviors like roaring, scent-marking, and mounting other females.
However, they found the two sisters had almost identical – and normal – levels of testosterone.
The answer instead rested on hormones found in Bridget’s adrenal gland, the small endocrine organ that regulates body systems. Here, cortisol that regulates metabolism and the immune system was 2.5 times higher than her sister’s. And androstenedione, which is the precursor to sex hormones like estrogen and testosterone, was seven times higher.
“The elevation of those two hormones together definitely indicates that she has some extra hormones floating around in her body that most likely caused this mane,” said Dr Jennifer D’Agostino, OKC Zoo Director of Veterinary Service, in a blog post.
Bridget’s “mini mane” probably comes from a small benign tumor pressing against the adrenal gland, which then secretes these hormones. But a little tumor won’t affect her too much: OKC says she’s in otherwise “excellent” health. As for her luscious new locks?
“We do suspect that she will continue to have her mane. I don’t think it’s probably going to get much bigger than it is now, but most likely she will have that for the rest of her life,” said D’Agostino.
Average life expectancy of the African lion is 15 years, but those living in captivity can grow to 30, according to the Zoological Society of London. D’Agostino says the zoo will continue monitoring Bridget’s health with several annual blood test, but otherwise, she’ll rock her normal routine.
We think she looks fabulous with or without the extra fluff. You do you, Bridget.
[H/T: OKC Zoo]