Why Lions Have Manes

lion
Lion, James Barker, FreeDigitalPhotos.net

While there have been a number of theories put forth, the purpose of a male lion’s mane was not known for sure until researchers devised an ingenious experiment.

Mane growth is regulated by the hormone testosterone. Male lions begin growing manes when they are around one year old, and by the time they are four years of age, the mane is fully grown.

A lion’s mane may comprise anything from dark foot-long tresses to a sparse crop of blond fur framing the neck and face. Manes are quite variable from one lion to the next, and an individual’s mane characteristics can also change in response to climactic conditions and other factors.

Some lions are so heavily maned that the long dark fur covers not only their heads and necks but also their foreheads, shoulders, and bellies. In some cases, there are even tufts of fur on the elbows.

There are three prominent theories that have been proposed to explain the purpose of a lion’s mane:

    • The thick fur protects the head and neck area when male lions fight.
    • A big mane makes a male lion look larger, thus intimidating his rivals.
    • Female lions find large manes attractive, so males with impressive manes have more mating opportunities.

West and Packer (2000) conducted research to test these theories. First, they found that when fighting, male lions were not inclined to attack the head and neck more often than any other areas of the body or to inflict more severe wounds in these areas. Also, other cats engage in equally deadly fights, yet the males of other feline species do not grow manes. Thus, it seems unlikely that the mane’s purpose is to offer protection during fights.

Next, the researchers shifted their focus to the role of the mane in competition between males and the ability to attract females. They created lifelike lion dummies with contrasting manes – short versus long and light versus dark – and observed how lions would react to them. Because lions often find food by listening for hyenas and then chasing them away from a carcass, the researchers played hyena noises to lure lions to their dummies.

The researchers found that male lions always preferred to approach the dummies with the light-coloured and the short manes, whereas female lions did not appear to care about mane length but they definitely had a colour preference, choosing most often to approach the dummy with the dark mane.

Female Lions Prefer Dark Manes on Males

Female lions most often mate with males that have the darkest manes, regardless of length. This is likely because males with darker manes are not only older and better nourished, but also tend to have higher testosterone levels, and thus a greater propensity for aggression.

The benefits to female lions in choosing mature, healthy, aggressive mates are significant. If other lions evict resident males and take over the pride, they will kill all of the existing cubs to bring the females into heat. Dark-maned males are able to hang onto their prides for longer and their young are less likely to be injured. Also, if they themselves are wounded, dark-maned males are more likely to survive their injuries. In addition, a robust male can also take down large prey such as giraffes or buffalo where these animals are available, providing a good feast for the pride.

The advantages enjoyed by dark-maned males also explain why male lions prefer to approach other males that have fair, short manes. These males are likely to be easier to defeat in a fight because they are usually quite young, injured, or less hormonally predisposed to be aggressive. Male lions with darker manes also get a higher share of the available food resources than those with lighter manes, which suggests that they usually are better nourished overall, and thus more likely to prevail in a fight.

However, dominant males pay a price for growing thick, long, dark manes. They suffer more from heat and as a result, may not be able to eat as much during the warmer months of the year, as taking in food increases body temperature. They are also more inclined to have deformed sperm due to their higher body temperatures. Males in hotter climates tend to have fairer, shorter manes overall to provide relief from the heat. As such, the colour and length of the mane may represent a trade-off between reproductive success and comfort.

References:

    • Seidensticker, John, & Lumpkin, Susan. (2004). Smithsonian Answer Book: Cats. Washington, DC: Smithsonian Books.
    • West, Peyton, & Packer, Craig. (2002). “Sexual Selection, Temperature, and the Lion’s Mane.” Science, 297, 1339-1343.

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