Well, so have we here at the Conservators Center, home to 15 African Lions and a wide variety of other exotic wildlife species. All seven of our male lions sport luxurious examples of the characteristic lion’s mane, ranging in color from sandy blonde to nearly black. Lions are the only Felid species who present such a dramatic example of sexual dimorphism in the form of the mane, which is typically only seen on male lions. Our female lionesses, most of which live with at least one male lion, tend to be slightly smaller in stature than our males and ordinarily lack the distinguishing feature of a mane – with one startling exception.
Daisy, our oldest and most crotchety lioness, has in recent years become our very own bearded lady, confounding her beloved keepers and puzzling our resident veterinarian who had never encountered a maned lioness before. The presence of a mane on a female lion is a rare occurrence, mostly documented as anecdotal anomalies, with minimal extant scientific research to explain such an unusual phenomenon. What is known is that males who are neutered lose their manes, and that high testosterone levels correlate with especially heavy and darker colored manes. We were curious about the cause of Daisy’s postmenopausal mane growth and decided to explore some other examples of female lions who had inexplicably sprouted manes in order to determine why our elderly lioness was suddenly presenting such a blatantly masculine feature.
Daisy was an adult when she arrived at the Center in 2004 along with 7 other lions. Three of these 8 lions were pregnant, but interestingly, Daisy was not one of them. We have no record of Daisy’s breeding history, so we do not know whether our bearded lady ever produced offspring of her own. If she had been pregnant and reared cubs at her previous facility, then her development of a mane later in life would be all the more strange based on the research findings we uncovered regarding maned lionesses.
We first noticed Daisy’s unusual facial hair growth a few months after her decision to live the single life in one of the more spacious and verdant enclosures in the park, which happens to be rather far away from all the other lions from her original extended pride, and their offspring. We say it was her decision to live there because we had originally moved Daisy and her male companion temporarily while we made some structural changes to their other space, and when it came time to move the pair back, the male willingly loaded into the transport crate while Daisy stubbornly stood her ground and refused to budge, even when we tempted her with her favorite treat - turkey legs! After weeks of trying to get the old girl to move, we realized the effort was completely futile, so Daisy had her way and has lived alone ever since.
Of the few studies that have been done on the secondary sex characteristics of lions, only one study to-date focused on mane growth in females, and the data collected was largely inconclusive. However, two years of vigilant observation of five maned lionesses living in the Moremi Game Reserve in Botswana’s Okavango delta led Geoffrey D. Gilfillan and his team of researchers from the University of Sussex to believe that pronounced mane growth in female lions may be concurrent with infertility.
Heterosexual copulation was observed in three of the maned lionesses, but no mating attempts proved to be successful throughout the duration of the study. Their findings, which were published in the African Journal of Ecology in 2016, suggest that female lions that develop manes may possess higher levels of androgens (male sex hormones) like testosterone than is normal for most reproductively successful lionesses.
Although we do not know whether Daisy’s unusual sprouting of facial hair has anything to do with her level of fertility, there have been a few fascinating reports in the news recently of other female lions developing manes as they age. The Oklahoma City Zoo just publicized their own account of unexpected mane growth in one of their older female lions, Bridget, and the story has gone viral. Apparently Bridget did give birth to a litter of cubs back in 2007, which adds a fascinating twist on the mystery of the mane.
One other lioness in captivity has been reported to have “sprouted a mane,” a female named Emma who had also successfully reproduced many years before the growth of her masculine whiskers. Emma’s caretakers at the National Zoo in South Africa decided to run some tests on her and discovered she had elevated levels of testosterone in her blood, as would be expected based on her development of a typically male trait, the mane.
The Conservators Center has witnessed rudimentary mane growth in a few other elderly female lions over the years of our lion-housing history, but Daisy’s voluminous locks have well outdone her minimally maned peers, thus giving rise to our burgeoning curiosity about why some female lions tend to sprout beards as they age. Our co-founder, Mindy Stinner, has theorized that the observed proliferation of mane growth in older lionesses in recent years may be due in part to the greater longevity of lions in captivity as a result of improved geriatric care, suggesting that perhaps hormonal imbalances leading to things like mane growth in senior female lions is a normal part of the aging process past productive hormonal activity. Of course, this theory is as yet unproven, but we think it would be a fascinating study for the scientific community to undertake as more captive lions are living into unprecedented seniority, giving rise to uncharted territory about what happens to lions as they age.
As iconic a species as the African Lion may be, and despite the universal symbolism of power and status attached to the image of the characteristic lion’s mane, there exists a surprising dearth of scientific evidence for the evolution of the mane. In light of the vast and varied theories for why male lions have manes and, conversely, why female lionesses typically do not, we cannot provide any concrete answers to the question of why our sweet old Daisy (or Bridget or Emma or the five maned lionesses of Botswana) has unexpectedly grown a mane of her own. We can, however, speculate with educated guesses and continue to be charmed by the rare spectacle of a bearded lady at the Conservators Center.
Based on the knowledge that mane growth in males is a result of increased testosterone production during puberty, and considering Emma’s heightened levels of testosterone in her bloodstream, it is likely that as Daisy has aged in isolation and advanced beyond the age of sexual maturity (think of her age transition as similar to menopause in humans), her levels of androgens like testosterone may have incrementally increased over the years, giving rise to the production of typically male characteristics such as an underdeveloped mane and more aggressive behaviors, both of which have been witnessed in Daisy in recent history.
We cannot confirm nor deny that mane growth in female lions has anything to do with infertility, although with respect to the cases of Emma and Bridget, it seems more likely that excess hair growth in the form of a mane in female lions may be connected with age, and could also be related to a genetic predisposition for a hormonal imbalance in the form of increased levels of androgens in the bloodstream. Despite not knowing exactly why our handsome girl grew a mane, we love her perhaps all the more for being such an interesting and unique individual, and we are certain that a bit of extra hair and testosterone will have no significant impact on her quality of life for all the years remaining to her.