A harem is an

animal Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage ...

group consisting of one or two males, a number of females, and their offspring. The

dominant male In biology, a dominance hierarchy (formerly and colloquially called a pecking order) is a type of social hierarchy that arises when members of animal social groups interact, creating a ranking system. A dominant higher-ranking individual is som ...

drives off other males and maintains the unity of the group. If present, the second male is subservient to the dominant male. As juvenile males grow, they leave the group and roam as solitary individuals or join

bachelor herd A bachelor herd is a herd of (usually) juvenile male animals who are still sexually immature or 'harem'-forming animals who have been thrown out of their parent groups but not yet formed a new family group. It may also refer to a group of males who ...

s. Females in the group may be inter-related. The dominant male mates with the females as they become sexually active and drives off competitors, until he is displaced by another male. In some species, incoming males that achieve dominant status may commit

infanticide Infanticide (or infant homicide) is the intentional killing of infants or offspring. Infanticide was a widespread practice throughout human history that was mainly used to dispose of unwanted children, its main purpose is the prevention of resou ...

. For the male, the primary benefit of the harem system is obtaining exclusive access to a group of mature females. The females benefit from being in a stable social group and the associated benefits of grooming,

predator avoidance Anti-predator adaptations are mechanisms developed through evolution that assist prey organisms in their constant struggle against predators. Throughout the animal kingdom, adaptations have evolved for every stage of this struggle, namely by avo ...

and cooperative defense of territory. The disadvantages for the male are the energetic costs of gaining or defending a harem which may leave him with reduced reproductive success. The females are disadvantaged if their offspring are killed during dominance battles or by incoming males.

Overview

The term ''harem'' is used in

zoology Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the animal kingdom, including the structure, embryology, evolution, classification, habits, an ...

to distinguish social organization consisting of a group of females, their offspring, and one to two males.Maestripieri, Dario; Mayhew, Jessica; Carlson, Cindy L.; Hoffman, Christy L.; and Radtke, Jennifer M.
One-Male Harems and Female Social Dynamics in Guinea Baboons
" Folia Primatologica 78.1 (2007): 56-68 The single male, called the

, may be accompanied by another young male, called a "follower" male. Females that closely associate with the dominant male are called "central females," while females who associate less frequently with the dominant male are called "peripheral females."Kummer, Hans. Social Organization of Hamadryas Baboons. A Field Study. Basel: Karger, (1968.) Print. Juvenile male offspring leave the harem and live either solitarily, or, with other young males in groups known as

s.David, J. H. M.
The Behaviour of the Bontebok, Damaliscis Dorcas Dorcas, (Pallas 1766), with Special Reference to Territorial Behaviour
" Zeitschrift für Tierpsychologie 33 (1973): 38-107 Sexually mature female offspring may stay within their natal harem, or may join another harem.Qi, Xiao-Guang; Li, Bau-Guo; Garber, Paul A.; Ji, Weihong; and Wanatabe, Kunio. "Social Dynamics of the Golden Snub-Nosed Monkey (Rhinopithecus Roxellana): Female Transfer and One-Male Unit Succession." American Journal of Primatology 71 (2009): 670-79 The females in a harem may be, but are not exclusively, genetically related.Greenwood, Paul J. "Mating Systems, Philopatry and Dispersal in Birds and Mammals." Animal Behaviour 28.4 (1980): 1140-162 For instance, the females in

hamadryas baboon The hamadryas baboon (''Papio hamadryas'' ) is a species of baboon within the Old World monkey family. It is the northernmost of all the baboons, being native to the Horn of Africa and the southwestern region of the Arabian Peninsula. These re ...

harems are not usually genetically related because their harems are formed by "kidnapping" females from other harems and subsequent herding. In contrast, gelada harems are based on kinship ties to genetically related females.Mori, Akio; Iwamoto, Toshitaka; Mori, Umeyo; and Bekele, Afework.
Sociological and Demographic Characteristics of a Recently Found Arsi Gelada Population in Ethiopia
" Primates 40.2 (1999): 365-81 Multiple harems may assemble into larger groups known as "clans" or "teams".Schreier, Amy L.; and Swedell, Larissa. "The Fourth Level of Social Structure in a Multi-level Society: Ecological and Social Functions of Clans in Hamadryas Baboons." ''American Journal of Primatology'' 71.11 (2009): 948-55 Harem cohesiveness is mediated by the dominant male who fights off invading males to keep claim over the harem. In some harem-forming species, when a dominant male vacates his harem (due to death, defection to another harem, or usurpation) the incoming male sometimes commits

of the offspring.Swedell, Larissa; and Tesfaye, Teklu. "Infant Mortality after Takeovers in Wild Ethiopian Hamadryas Baboons." American Journal of Primatology 60.3 (2003): 113-18 Because time and resources are no longer being devoted to the offspring, infanticide often stimulates the female to return to

sexual receptivity Animal sexual behaviour takes many different forms, including within the same species. Common mating or reproductively motivated systems include monogamy, polygyny, polyandry, polygamy and promiscuity. Other sexual behaviour may be reprodu ...

and

fertility Fertility is the capability to produce offspring through reproduction following the onset of sexual maturity. The fertility rate is the average number of children born by a female during her lifetime and is quantified demographically. Ferti ...

sooner than if the offspring were to survive. Furthermore, while

lactating Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process naturally occurs with all sexually mature female mammals, although it may predate mammals. The proces ...

, females do not ovulate and consequently are not fertile. Infanticide therefore has the potential to increase the incoming male's reproductive success.Horev, Aviad; Yosef, Reuven; Tryjanowski, Piotr; and Ovidia; Ofer. "Consequences of Variation in Male Harem Size to Population Persistence: Modeling Poaching and Extinction Risk of Bengal Tigers (Panthera Tigris)." Biological Conservation 147.1 (2012): 22-31

Benefits

Harems are a beneficial social structure for the dominant male, as it allows him access to several reproductively available females at a time. Harems provide protection for the females within a particular harem, as dominant males will fiercely ward off potential invaders. This level of protection may also, such in the case of the

common pheasant The common pheasant (''Phasianus colchicus'') is a bird in the pheasant family ( Phasianidae). The genus name comes from Latin ''phasianus'', "pheasant". The species name ''colchicus'' is Latin for "of Colchis" (modern day Georgia), a countr ...

, reduce the energy expended by females on remaining alert to, or fleeing from, invading males. Harems allow bonding and socialization among the female members, which can result in greater control over access to females as determined by the females' preferences. Harems also facilitate socialized behavior such as grooming and cooperative defense of territory.Searcy, William A.; and Yasukawa, Ken.
Alternative Models of Territorial Polygyny in Birds
" The American Naturalist 134.3 (1989): 323-43

Costs

Harems can prove energetically costly for both males and females. Males spend substantial amounts of energy engaging in battles to invade a harem, or to keep hold of a harem once dominance has been established. Such energy expenditure can result in reduced reproductive success such as in the case of

red deer The red deer (''Cervus elaphus'') is one of the largest deer species. A male red deer is called a stag or hart, and a female is called a hind. The red deer inhabits most of Europe, the Caucasus Mountains region, Anatolia, Iran, and parts of ...

. This is especially true when there is high turnover rates of dominant males, as frequent intense fighting can result in great expenditure of energy. High turnover rate of dominant males can also be energetically costly for the females as their offspring are frequently killed in harems where

occurs. Harems can also negatively affect females if there is intra-harem competition among females for resources. A lower-cost

alternative mating strategy An alternative mating strategy is a strategy used by male or female animals, often with distinct phenotypes, that differs from the prevailing mating strategy of their sex. Such strategies are diverse and variable both across and within species. Anim ...

, useful to bachelors without a harem, is kleptogyny or the "sneaky fucker strategy", sneaking in to mate while the harem owner is distracted: in the case of

, when the harem stag is involved in a fight with another older stag. The strategy is also recorded in the elephant seal.

Examples

Animals that form harems include:

Mammals

Red deer The red deer (''Cervus elaphus'') is one of the largest deer species. A male red deer is called a stag or hart, and a female is called a hind. The red deer inhabits most of Europe, the Caucasus Mountains region, Anatolia, Iran, and parts of ...

Bonenfant, Christophe; Gaillard, Jean-Michel; Klein, François; and Maillard, Daniel. "Variation in Harem Size of Red Deer (Cervus Elaphus L.): The Effects of Adult Sex Ratio and Age-structure." Journal of Zoology 264.1 (2004): 77-85 * Sika deer * Elk * Fallow deer * Collared Peccary * Fur seal * Elephant sealMcCann, T. S.
Aggression and Sexual Activity of Male Southern Elephant Seals, Mirounga Leonina
" Journal of Zoology 195 (1981): 295-310. Web. *

Greater short-nosed fruit bat The greater short-nosed fruit bat (''Cynopterus sphinx''), or short-nosed Indian fruit bat, is a species of megabat in the family Pteropodidae found in South and Southeast Asia. Description These bats have a relatively long snout. Their upper p ...

Storz, Jay F.; Bhat, Hari R.; and Kunz, Thomas H.
Social Structure of a Polygynous Tent-making Bat, Cynopterus Sphinx (Megachiroptera)
" Journal of Zoology 251.2 (2000): 151-65 * Jamaican fruit batOrtega, Jorge; Maldonado, Jesus E.; Wilkinson, Gerald S.; Arita, Hector T.; and Fleischer, Robert C.
Male Dominance, Paternity, and Relatedness in the Jamaican Fruit-eating Bat (Artibeus Jamaicensis)
." Molecular Ecology 12.9 (2003): 2409-415 *

African lion The lion (''Panthera leo'') is a large cat of the genus '' Panthera'' native to Africa and India. It has a muscular, broad-chested body; short, rounded head; round ears; and a hairy tuft at the end of its tail. It is sexually dimorphic; adu ...

(harem referred to as a "pride") with the infrequent strategy of two coequal males (often brothers) who enter the territory of an existing harem and share the dominance, which makes it easier to depose the existing alpha male.

Primates

Hamadryas baboon The hamadryas baboon (''Papio hamadryas'' ) is a species of baboon within the Old World monkey family. It is the northernmost of all the baboons, being native to the Horn of Africa and the southwestern region of the Arabian Peninsula. These re ...

Gelada baboon The gelada (''Theropithecus gelada'', am, ጭላዳ, translit=č̣əlada), sometimes called the bleeding-heart monkey or the gelada baboon, is a species of Old World monkey found only in the Ethiopian Highlands, living at elevations of above se ...

Golden snub-nosed monkey The golden snub-nosed monkey (''Rhinopithecus roxellana'') is an Old World monkey in the subfamily Colobinae. It is endemic to a small area in temperate, mountainous forests of central and Southwest China. They inhabit these mountainous fores ...

Guinea baboon The Guinea baboon (''Papio papio'') is a baboon from the Old World monkey family. Some (older) classifications list only two species in the genus ''Papio'', this one and the hamadryas baboon. In those classifications, all other ''Papio'' specie ...

Gray langurs Gray langurs, also called Hanuman langurs and Hanuman monkeys, are Old World monkeys native to the Indian subcontinent constituting the genus ''Semnopithecus''. Traditionally only one species ''Semnopithecus entellus'' was recognized, but since ...

Agoramoorthy, Govindasamy.
Adult Male Replacement and Social Change in Two Troops of Hanuman Langurs (''Presbytis entellus'') at Jodhpur, India
." International Journal of Primatology 15.2 (1994): 225-38 *

Chimpanzee The chimpanzee (''Pan troglodytes''), also known as simply the chimp, is a species of great ape native to the forest and savannah of tropical Africa. It has four confirmed subspecies and a fifth proposed subspecies. When its close relative t ...

Gorilla Gorillas are herbivorous, predominantly ground-dwelling great apes that inhabit the tropical forests of equatorial Africa. The genus ''Gorilla'' is divided into two species: the eastern gorilla and the western gorilla, and either four ...

Birds

Common pheasant The common pheasant (''Phasianus colchicus'') is a bird in the pheasant family ( Phasianidae). The genus name comes from Latin ''phasianus'', "pheasant". The species name ''colchicus'' is Latin for "of Colchis" (modern day Georgia), a countr ...

Ridley, M. W.; and Hill, D. A.
Social Organization in the Pheasant (Phasianus Colchicus): Harem Formation, Mate Selection and the Role of Mate Guarding
" Journal of Zoology 211 (1987): 619-30 *

Greater rhea The greater rhea (''Rhea americana'') is a species of flightless bird native to eastern South America. Other names for the greater rhea include the grey, common, or American rhea; ema (Portuguese); or ñandú ( Guaraní and Spanish). One of two ...

Codenotti, Thaïs L.; and Alvarez, Fernando.
Mating Behavior Of The Male Greater Rhea
" The Wilson Bulletin 113.1 (2001): 85-89 *

Northern harrier The northern harrier (''Circus hudsonius''), or ring-tailed hawk, is a bird of prey. It breeds throughout the northern parts of the northern hemisphere in Canada and the northernmost USA. The northern harrier migrates to more southerly areas ...

* red-winged blackbird

Insects

Bark beetle A bark beetle is the common name for the subfamily of beetles Scolytinae. Previously, this was considered a distinct family (Scolytidae), but is now understood to be a specialized clade of the "true weevil" family (Curculionidae). Although the ...

Latty, Tanya M.; Magrath, Michael J. L.; and Symonds, Matthew R. E.
Harem Size and Oviposition Behaviour in a Polygynous Bark Beetle
. ''Ecological Entomology'' 34.5 (2009): 562-68 *

Tree weta In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are u ...

Kelly, Clint D.; and Jennions, Michael D.
Sexually Dimorphic Immune Response in the Harem Polygynous Wellington Tree Weta Hemideina Crassidens
. ''Physiological Entomology'' 34.2 (2009): 174-79 * Malaysian stalk-eyed fly forms temporary harems even though mating frequency is high and the behavior of multiple mating partners is common.

Fish

Hogfish The hogfish (''Lachnolaimus maximus''), also known as boquinete, doncella de pluma or pez perro in Mexico is a species of wrasse native to the Western Atlantic Ocean, living in a range from Nova Scotia, Canada, to northern South America, in ...

* Several species of

cichlid Cichlids are fish from the family Cichlidae in the order Cichliformes. Cichlids were traditionally classed in a suborder, the Labroidei, along with the wrasses ( Labridae), in the order Perciformes, but molecular studies have contradicted th ...

* California sheephead

Explanatory notes

References

{{Ethology Behavior Ethology