The Sisterhood
by Hilde Grov
Abstract of original research paper
1: Proc R Soc Lond B Biol Sci. 2003 Jun 22;270(1521):1247-54.
Sexual conflicts in spotted hyenas: male and female
mating tactics and their
reproductive outcome with respect to age, social status and tenure.
East ML, Burke T, Wilhelm K, Greig C, Hofer H.
We investigated the reproductive outcomes of male and
female mating tactics in the spotted hyena, Crocuta crocuta, a female-dominated
social carnivore with high maternal investment, an absence of paternal
care and female control over copulation. Paternity was determined using
microsatellite profiling of 236 offspring in 171 litters from three clans.
We found little evidence that male tactics that sought to coerce or monopolize
females were successful. Polyandry and sperm competition appeared to counter
effectively pre-copulatory male
tactics, such as harassment, monopolization and other tactics, such as
infanticide, that were against the evolutionary interests of females,
and may have contributed to the stability of the male dominance hierarchy,
which operated as a social queue. At least 39% of 54 females mated multiply,
and 35% of 75 twin litters were fathered by two sires. Polyandry may also
serve to ensure fertilization, compensate for an initial poor-quality
mate or ensure fertilization by genetically compatible mates. Female mate
choice matched observed patterns of affiliative male-female behaviour,
indicating that affiliative behaviour is a successful male mating tactic,
and was consistent with the idea that male tenure may serve as an index
of male quality, although male fertility may decline with extreme old
age.
When talking about hyenas, people usually think of the spotted hyena of Africa. It is also the hyena species this assaz will focus on, only mentioning some key features of other species of the family.
The hyena has not been concidered beautiful like the lepard or royal like the lion.
Spotted hyenas have a bad reputation all over the world as cowardous, but araggressive killers and scavanger, that will eat about anyhthing, beeing other dead animals (even hyenas), humans, insects or even fruits. Their very characteristic voice sounds like a course hysterical laugther, and they are by most people considered to be ugly beasts.
(This negative image is tougth to be based on observations made of hyenas eating human corpses).
This was also my impression of hyenas, and like most people, all I knew about them.
After learning a bit more, I understood that this animal is truly amazing and uniqe in the animal kingdom. First of all when it comes to their social structure, with all the females ranking higher than the males, but also in other aspects like their great variety of food sources, their anatomy and physiology.
With this assay I aim to give a general description of theese facinating creatures, with special attention to the building up of their social hierarchy.
Hyenas have allways been object to folklore and superstition.
Many african cultures, even today, concider them to be connected to whichcraft. They are believed either to be the Whiches` "nigth cattle", beeing milked and used to ride on through the nigth to the which seremonies. Or that the which actually turns herself into the hyena during the nigth, and roam the african savannas.
Other cultures concider the hyena to be some sort of divine undertaker, which transport the human soul to the afterlife...by eating it!
The arabic people, and the europeans traditionally associate the hyenas with perversions and homosexuality due to the females extremely enlarged clitoris. and they were tougth to be able to change sex back and forth.
There is evidence that there in the ice ages existed a giant prehistoric hyena at many locations, and cave paintings proves that the spotted hyena has survived in more or less it`s present form for over 20 million years.
Usuallz people assume that the hyena is closely related to the dog. this is a mistake. their relationship to the cat is much closer.
they belong to the family hyaenidae, which comprises four species:
- spotted hyena (crocuta crocuta)
- brown hyena (parahyaena brunnea)
- striped hyena (hyaena hyaena)
- aardwolf
The spotted hyena is the biggest and the most intensivly studied.
It is found throughout most of africa south of the sahara exept the rainforrest and the mountain tops.
(The striped hyena is found in north Africa, southwest asia and india, the brown in limited areas of southern Africa, and the small ardwolf is found in south and east of Africa).
The brown hyenas also have females on top of the social ladder, but they are not nearly as aggressive in their ruling as the spotted females. neither do they have the grossly enlarged clitoris. They are mainly scavengers and search for food individually during the nigth. they also like to vary their diet with fruits.
The striped hyena is found in the middle east, and is like the brown, more solitary and more scavanger than hunter.
The aardwolf is the least terrifying of the hyena familz. Actually it is so specialized to eating terimites (they can consume up to 30 000 terimites in one nigth), that its teeths are reduced to harmless pegs, exept for the canines which are used in territorial figths. Since they feed alone, they never developed a clan system. They are as humans, more or less monogamous. The female may sneak off during the nigth to mate with a more attractive male before returning to her mate. But if she is not discret about it, her male migth abandon her and her cubs.
All four species of hyenas are decreasing in number, mostly due to decreas in food sources and territories, but also due to endless persecution.
THE SPOTTED HZENA
The biggest and most agressive of its family. It is between 70-92 cm tall and weigh between 55-85 kilos. They have a relatively low back part and a corse coat of mainly guard hairs.
Hyenas prefer open land and even semi-dessert, and are rarely found in forrests. They have developed the ability to go for several days without water.
The territory is marked with a thick evil-smelling secretion from their anal glands (a highly unplesant smell, which also surrounds the animals). The social center of the clan is the common dung, where the cubs remains and the voilent arguments take place. Hyenas migth roam as far as 40-80 km from their home dung in search of food.
They are the dominant predator of Africa, and dispite a reputation as scavangers, their diet only comprises about 5% carrions. This is highly dependent on the availability of live prey. On the top of the menu they have wildbeest, gazelles, zebra, buffalos and most ungulate species. Normallz they hunt alone and at nigth, but will hunt in packs to catch large pray, or steal prey from lions. Typically they chase their prey until it is exhausted, an then kill it by tearing it apart. Allthough they win mainly on basis of endurance, they are capable of running at speed up to 65 km pr hour. for shorter periods. They have the strongest jaws in the animal kingdom, and can easily break a human leg with one bite. Their digestive szstem is also extremely well developed, f.ex. their stomach juice is more acidic than other carnivores. Thez can digest all parts of their kill, including bones, hooves and fur.
They usually consumes their prey at the site of the kill, and can eat one third of their body weigth in one feeding frency.
Lions and hyenas are concidered eternal enemies, most likely due to the fact that they compete for the same food, and that hyenas (exept for other male lions) are the major predator of lion cubs. Lions account for 50% of all hyena deaths, where the dead hyenas are not eaten but left to rot. In some areas the primary food source for lions are what they can steal from hyenas.
But there have also been observations of large packs of hyenas (up to 40 individs) challanging lions to figth.
In these kinds of disputes, it has been noted that the lions (including the male) seems to seek out the dominant female and kill her.
The hyena is both matriarchal and hierarchial.
As many as 80 (usually 30-40) hyenas live together in large clans, which divide into packs. Centrally in the clan is a group of related females forming the top of the hierarchy, where the older or the stronger one is the leader. Male dominance is almost universal among mammals, which makes this social structure wery interesting. The highest ranking male, is still under the lowest ranking female.
Studies of Serengeti spotted hyena clans have showed on which basis the females choose their males. They do not choose the dominant male, nor the most aggressive. They pick the friendly ones that focused on grooming, greeting etc. The time spent with the clan is also concidered an important factor for the females, they want a male that sticks around. But males are males also in the hyena society, and the they tried several other tactics...
- mild harassment is when males are approaching females agressively, biting, grovling and
trying to mate with them without their cooperation.
- intense harrassment (baiting) where coalitions of males attach a solitary female.
- shadowing is when a male will follow a female for weeks, even months.
- defending behavior is when a male try to defend her against other males.
(Does theese tactics seem familiar...?)
Neither of these tactics gives the males any advantage, it even showed that the male defending his choosen female actually decreased his chances to mate with her.
The spotted hyena are sexually mature around 3 years (females a bit later). Young males often leave the clan while females always stays.
The females are usually bigger, more agressive and have a penis like clitoris which causes problems, and many deaths of both the mother and the cubs, during delivery.
(Copoulation is carried out as usual).
The females leave the clan to give birth to, usually two offsprings. The cubs are born in an advanced state of development. they are 1.5kg, black, have teeth and open eyes.
Their aggressive nature is evident only hours after birth, when same sex siblings start to figth for dominance, often ending in the death of the weaker cub. The figth between sisters is the most fierce. cubs can remain without food or care for days while the mother is hunting. She will not bring food to the cubs other than the concentrated milk she is producing (four times the concentration of cow milk and with a very high protein content).
After 2-4 weeks the mother bring her cub(s) to the clan. The female cubs automatically takes the hiercial position rigth below that of her mother, and will from this point start her figth to keep it, or advance.
The clan commonly nurtures and cares for the young, allthough males to a lesser extent than females.
The hyena can live to be 20 years in the wild, which is quite impressing concidering their feeding habits. In captivity they can even reach 40.
Hyenas are constantl decreasing in number. Some places in africa they have been completely eliminated to save lifestock like sheeps and goats. Other places their nuber is decreasing due to lack of ungulates and territory.
Earlier a great effort were made to introduce hyenas to nature reserves, this activity has declined the later years.
But it is not to late! One thing we all can contribute to, is changing the negative reputation this amazing animal have, and educate the people.
Referances
Royal Society of Britain`s report on sexual politics of spotted hyenas
www.pubs.royalsoc.ac.uk
Kruuk,Hans.1972 " the spotted hyena-a studz of predation and social behavior"
www.liberalmafia.org
www.zoo.org
www.lib.montana.edu
Notes (if any) by Peter Kabai:
Hilde found an interesting site I was not aware of. Hyenas on leash on a busy street:
Go to the site to see all pics: http://www.bizarsite.nl/Nigeriaanse%20geld%20ophalers.html