When you think of a lion, what is the first image that comes to mind? Is it a large male with a dark, impressive mane around the neck and shoulders? Or a group of maneless females with their cubs?
Lions are linked intrinsically with their manes, or the lack thereof. Males have them; females don’t. And yet, as with everything, there are exceptions to the rule.
Maneless Lions of Tsavo
The Tsavo Conservation Area of Kenya is home to an unusual population of maneless male lions. These males have a very small mane, if they have one at all. Lion manes are linked to levels in testosterone – the testosterone promotes the growth and influences the color. However, testosterone isn’t the only factor. A lion’s genetics, health, and even environment can influence the mane’s appearance.
The region of Tsavo is very hot and full of dense, thorny foliage. Both factors may very well be the cause for these lions’ lack of mane. Large manes often absorb heat, while it is likely difficult to hunt in dense foliage with a thick mane. Tsavo males also have a slightly different social structure than males in other areas of Africa: instead of living together in a coalition, they typically live alone. Coalitions in most of Africa are more successful at leading prides than individual lions. The structure of Tsavo could be due to either a scarcity in prey or higher testosterone levels, which may lead to increased aggression.
Maned Lionesses
It is rare, but not impossible, to find a female lion with a mane. The growth of manes is caused by testosterone, so only females with unusually high testosterone levels will develop one. The first officially documented case of wild female lions with manes was during a study between 2014 and 2016. Scientists studied five females with manes in the Okavango Delta of Botswana. One of the lions, Mmamoriri, had a full, dark mane and behaved similar to a male when it came to scent-marking and caroling frequency. Mmamoriri may be seen as a male by other prides, which could benefit her own pride – prides with more males are typically more successful. However, these maned lionesses are likely sterile, and with the isolated nature of the Okavango Delta this could be an issue.
Animals have traits that help them survive. While the majority of a species may have a similar trait, certain populations may have different mutations to help them survive. Tsavo lions lack manes, possibly due to challenges of their specific environment. Mutations can also be caused by the isolated nature of certain populations, which could lead to issues for the population as a whole.
Sources
Figure 1: https://lionrecoveryfund.org/maneless-male-lions/
Figure 2: https://africageographic.com/stories/unravelling-the-mystery-of-mmamoriri-the-maned-lioness/
https://tsavotrust.org/why-are-tsavos-male-lions-maneless/
https://www.lionstigersandbears.org/the-life-cycle-and-significance-of-the-lions-mane/
https://2024.sci-hub.se/5891/8f0bdbe9661dccc4b3b5acf43cda8531/gilfillan2016.pdf
https://www.thirteen.org/programs/nature/nature-mmamoriri-maned-lioness/
*Published by Eryn Meeker on 11/22/2025*