Spotted Hyena (Crocuta crocuta)

The spotted hyena's physical appearance and unusual characteristics have made it often the subject of hatred and disdain but rarely scientific interest. Thus through much of history the hyena was overlooked despite being the #2 predator in Africa. There have been very few whom have taken an interest in the creatures. Those scientists are few and far between but have made great leaps in our understanding of this fascinating species. What they have uncovered is far stranger than the myths surrounding the species and may give us a view into how male and female sex characteristics come into being as well as what role hormones play in making us who we are. Recent findings may even give us the clues to how prostate cancer can be controlled.

Physical

• Masculinized females. Suspected pathway is Anderostendione is converted into Testosterone by the placenta bathing the cubs in hormones. However research shows blocking this does not stop masculinization showing a more complex pathway exists.
• Females have a phallus, almost identical in shape to the male's penis but which they copulate, urinate and give birth through. Fatty bodies in false scrotum mimic testes.
• Origin tissue and structure of genitals different in males and females. Males must get hard to breed, females must get soft and retract. Subtle differences in morphology are males have a more pointed tip, less elastic meatus and longer shaft. Females are blunter tipped with a slightly shorter shaft.
• Gestation is around 110 days.
• Umbilical cord is shorter than birth canal. First time moms suffer tearing and high mortality rates among their cubs since their meatus hasn't stretched sufficiently. Self-episiotomies are common to enlarge the opening.
• Males have a bulbous glans that locks with the female upon insemination.
• Males have barbs to possibly induce ovulation in females. Females have barbs but at a reduced number.
• Strong jaws and specialized teeth for crushing bones.
• Major upper body strength for taking down very large prey.
• No interdigital fur.
• Post-anal scent gland which they invert to mark territory. Secretions are made of a short term and longer lasting modified sweat gland product that blends together to form a light gray paste. This is the origin of the hyena butter references.

Hyenas have been known for their unusual sexual dimorphism. In a usual mammalian species, males are bigger, stronger and more aggressive then females. In hyenas this is reversed. Female spotted hyenas are bigger, stronger and more aggressive than their male counterparts. Females outrank males so even the highest ranking male is lower than the lowest ranking female.

Female's unusual qualities don't end with just being dominant. Their external genitalia look strikingly like a male's complete with a pseudo scrotum with fatty bodies that mimic testes. The females have a large peniform clitoris. This phallus can get erect and it is used as a shared urogenital tract. She urinates, copulates and gives birth through the structure.

This unusual structure makes giving birth quite difficult. The umbilical cord is shorter than the birth canal so before the cub emerges the placenta has to detach. The cub only has a limited time to leave the birth canal or suffocate. The meatus is also another stumbling block as first time mothers are most at risk. The meatus undergoes significant tearing to allow a large enough opening to allow the cub to pass through. Mothers will often bite at the opening to help tear it so the cub can emerge. Subsequent births are a bit easier on the moms and cubs so mortality rates are lower for second time moms.

Social

• Exist in highly social groups called clans. Clans range from as few as a dozen to upwards of 100 individuals.
• Females outrank males. Males immigrate into a new clan upon reaching maturity.
• Cubs inherit mother's rank. Rank is maintained even if mother isn't present. Females stay in clan and assume mother's rank.
• Upon birth strong aggression is displayed. Born with fully erupted teeth. Bite-shake behavior against any sibling. This behavior switches to a play behavior at around two weeks of age. Mothers will attempt to break up cub's aggression if possible. In the wild it is difficult since the cubs are down in abandoned aardvark burrows and away from mother's ability to break up aggressive behavior.
• Gender specific roles are reversed. More play in females than males. However when males and females are together, play difference equals out.
• Engage in scent rolling to solicit positive attention from higher ranking individuals.
• Accomplished hunters. Use tactics and teamwork to bring down large prey.
• Clans keep territories they actively defend from other clans.
• Greeting ceremony involved the lower ranking individual lifting their hind leg exposing their erect genitals to a higher ranking individual. They must read the social cues or risk never passing their genes on. This leads one to believe that those with the most social savvy are the ones to pass on their genetics. Females may choose males based on this trait since strength and rank are moot points since females occupy those.
• Witnessed males fail to pass on genes because they were too scared of the female. Males must be brave and able to read cues of the female. Greeting ceremony through copulation.

Hyenas exist in highly social groups called clans. Clans range from as few as a dozen to upwards of 100 individuals. Social structure is quite rigid with females outranking males and rank being inherited from mother to daughter. Male cubs leave the clan during puberty and immigrate to a new clan where they slowly work their way back up the social hierarchy. Cub rank is respected even if the mother is not immediately present as experiments have shown cubs of higher ranking females asserting their rank over a lower ranking adult and successfully procuring their food despite being half the adult's size. This rank system keeps order and allows for an effective utilization of resources and minimizes conflicts between individuals.

The hyena's cooperation in large groups allow them to be quite effective hunters. It also allows them to defend their territory against other clans as well as defend against lions. Existing in a larger group however requires many things. First off you need an effective means of communication. Hyenas have a wide range of vocalizations for both close and long distance communication between clan-mates. Studies show there may be quite a bit of embedded information in their communication such as rank and other useful information to aide in an effective response. Hyenas utilize whoops, groans and giggles to convey their message. They also have other means such as body posture and scent glands.

Hyenas have a greeting ceremony which involves the lower ranking individual lifting their hind leg, exposing their genitals for inspection as the dominant one will sniff and lick, then raising their own leg for inspection. This puts the lower ranking animal at a distinct disadvantage in case the higher ranking one should want to punish them or attack them. In the wild it has been reported that many times hyenas will be seen with mutilated genitals from failed greeting ceremonies.

Socialization is generally hard wired in creatures that live in a complex society. Attention from superiors is rarely positive so lower ranking individuals utilize tricks such as scent rolling to give themselves an interesting odor to illicit positive interactions from their clan-mates. Grooming is also another common activity however usually it is a subordinate grooming a higher ranking individual.

Gender roles are generally reversed in hyenas. One such example is play behavior. In most mammals males play more than females but in hyenas it is the opposite. However in gender mixed groups the males lower the play rates and the gender bias is negated.

Typical female mammals generally tend to choose males based on who is biggest strongest and can provide the most food for their offspring or pass on the best genetics. In hyenas however the females are bigger, stronger and far more formidable hunters than the males so it begs the question, what does a female hyena look for in a male? One such answer might be buried in the above. Society. Males which demonstrate a superior ability to read female behavioral cues and read their social surroundings should pass on their genes more frequently. Thus social savvy may be the biggest 'turn on' for a female hyena looking for a potential mate. The earlier mentioned failed greeting ceremony would be a more immediate end to a male's ability to reproduce and removing their genes, thus those who don't make any social 'mistakes' will be at a far higher advantage to passing on their genes, even with just the greeting ceremony being taken into consideration.

Environment

• Direct competition with lions. Lions often chase hyenas off prey.
• Humans encroach on their environment.
• Limited but popular positive interactions such as Harare and humans keeping the hyena clan friendly which in turn keeps other possibly less friendly hyena clans away.

Hyenas hold a special place in the ecosystem as apex predators. They share this position with lions and clashes over resources are common. Hyenas are skilled hunters and often bring down prey much larger than themselves. Hyenas often hunt at night taking advantage of their superior vision. Lions, being larger than individual hyenas will often be attracted to the commotion and drive hyenas off of a kill. When dawn breaks humans often see the lions perched over a half eaten carcass with the hyenas attempting to reclaim their kill and assume the lions were the original hunters. However displacing the original predator only makes sense. Why risk the injury and energy expenditure of the initial kill when you can displace the original predators? However it is not always so easy, clashes are common and generally speaking whomever has the most raw weight on their side wins the clashes over food. It takes a few hyenas to equal one lion so it seems raw weight is a good determining factor. Scavenging also makes good sense. Why risk injury when food is lying around ready to be eaten? The ability to scavenge off food sources others cannot such as the marrow inside of thick bones has given hyenas a distinct advantage in lean times and harsh climates. We could almost call hyenas apex scavengers as they can get at food which other scavengers cannot. This dual role as both apex predator and scavenger has lead them to be far more resilient than other species to harsh environments and changing environmental pressures.

Like almost all African animals, human encroachment is the biggest threat to hyena populations. Luckily hyenas are far more adaptive and have fared the problem of decreasing habitat better than other species. That being said, the human view of them is often very poor and they regularly fall victim to farmers who poison, shoot and trap them as well as becoming victims to interactions with vehicles along ever increasingly common roadways. There are very few locations which see hyenas in a positive light. Harare Ethiopia is one such location where the towns folk welcome their local pack of hyenas into the town to help clean the streets of scraps and garbage. As well as cleaning up after the town the hyenas are regularly fed by a special hyena caretaker. This not only keeps the hyenas friendly but also increases that clan's ability to remain strong and hold off rival clans and other predators who might not be as friendly towards the town's population. In such, the clan becomes the town's defenders. Such mutually beneficial interactions are rare but could be used as an example for future human/hyena relations. Coexistence is rarely seen as a viable option, so the future looks bleak unless land can be set aside for parks and preserves. Maintaining and protecting that land takes resources, dedication and most of all money. Other animals which have a far more positive view by humans are usually the focus of preservation efforts yet hyenas will still benefit from any land set aside for the natural ecosystem. Environmental pressure and disease has taken a toll. What the future holds for the species is still unsure.

Problems

• Poor reputation among indigenous and non-indigenous people lead to difficulty in conservation and research.
• Very little research carried out over the years compared to other apex predators.
• Much of the detailed data especially with neonatal aggression and play behavior difficult to observe in wild. Most has come from UC Berkeley. The hyenas there have given us much of what we know, scientific and otherwise. They are easily observed there and that lead entities such as National Geographic, BBC, Skywalker Sound and Disney to visit to collect video, sound and artistic references. You can say much of what we hear and see that has hyenas in it came from there as well.