A small group of giraffe.
Image taken with permission from Hedweb
Giraffe social organization is characterized by loose, fluid herds with few affiliations observed between individuals. In fact, Pratt (1985) defined a group of giraffe
as "a collection of individuals that are less than a kilometre apart and moving in the same general direction."
Even under this broad definition, giraffe groups are highly transient, changing composition every few hours, with the exception of calving groups, which may be loosely maintained over weeks or months (Leuthold 1979).
Overall, the hallmark of giraffe social grouping is convenience, not social bonds. The only significant bond observed in giraffe is that of a cow and her calf (see parental care).
Nonetheless, giraffe are often found in transient aggregations, which occur when individuals are browsing near a common food source.
Adult male giraffe are fairly solitary, spending most of their time alone. Females are more often found in mixed groups, and calves and subadult giraffes are rarely alone (Dagg 1976; Pratt 1985).
Group sizes in giraffe range widely from one or two individuals to over 40, though small groups of a few individuals are the most common size (Ciofolo 2002). Group size is influenced by food availability; in areas where food is abundant, giraffes tend to aggregate--leading to larger group sizes. However, when food is sparse (e.g. during the dry season) smaller and more dispersed groups are observed (Le Pendu 2000).
A small group of giraffe.
Image taken with permission from Hedweb
Though they do not exhibit a complex social structure, giraffes in a given geographic area are usually familiar with their neighbors. A variety of greetings and contact types have been observed between individuals of both sexes and all ages. However, the types of interactions that are most commonly observed vary according to individuals' sex and age. Overall, nosing and licking are the two most common contact interactions between giraffes, and probably serve both a bonding and recognition function (Dagg 1976).
According to Le Pendu (2000), Leuthold (1979) and Pratt (1985), juvenile and subadult males associate with one another more often than most other giraffe groups, mostly in the form of necking behavior. Necking, also called playfighting or sparring, is observed on a regular basis among young adult male giraffes. In this ritualized practice, males take turns hitting one another with their massive necks and heads. Leuthold (1979) observed young adult males engaged in sparring behavior for up to 1-2 hours a day. Injuries rarely result from these exchanges, and male giraffe may alternate peacefully between sparring and browsing in groups (Pratt 1985). Male-male mounting has also been observed in conjunction with necking behavior, leading some researchers to conclude that it is a sexually based activity (Coe 1967; Leuthold 1979).
Two young males sparring.
Image taken with permission from http://randm2.tripod.com/index.html
An early paper written by Coe (1967) asserted that necking behavior is a "sexuo-social bonding mechanism" for young males as they build a dominance hierarchy for obtaining female mates. Coe believed that necking had sexual significance for males, as males were often seen with unsheathed penises (and occasionally mounted one another) while necking. Coe's assertion that necking is sexually stimulating for males is not universally accepted, but most scholars agree that necking is involved in the development of a dominance hierarchy among males of a given population of giraffe (Coe 1967; Pratt 1985; Simmons 1996). Necking behavior allows males to assess the relative strength of their peers in a fairly non-aggressive setting. By constantly sparring, juvenile and young adult males 'compete' with one another ahead of time, in order to avoid fighting and injury in the presence of estrous females.
Pratt and Anderson (1985) noted that, in cases of sparring between males of different sizes, it is usually the smaller males that initiate the match. They speculate that sparring is primarily an activity initiated and maintained by young males who are still establishing their relative ranks. Through the course of their study, these authors divided the adult male giraffe into three classes--A, B, and C bulls--based on body, head and neck size and horn development.
Pratt and Anderson found that Class C bulls spent the most time sparring: they observed 38 percent of the Class C bulls engaged in necking behavior over the course of 668 observations. In contrast, 12 percent of Class B bulls were found sparring over 359 observation periods, and no Class A bulls were ever seen sparring over the 96 observation periods in which they were seen. The authors concluded that sparring was an "adolescent" male behavior, likely cementing social rank in a linear dominance hierarchy. The oldest and most dominant Class A and B males have already established their rank; therefore, they are more solitary and spend more time pursuing females and less time interacting with other males.
Male giraffes' necks and heads continue to gain mass throughout their lives.
Males also develop extra bony growths, called ossicones, on their heads (Pratt 1982; Simmons 1996).
This male has prominant ossicones, and would be classed by Pratt as a Class A bull.
Image taken with permission from Ralf Schmode
In conclusion, sparring behavior is primarily dominance-related. Pratt and Anderson (1985) found that among their study population, class was highly correlated with dominance rank, with Class A bulls almost always more dominant than B bulls, who were likewise dominant over Class C bulls. Class C bulls, the least dominant, sparred most often, and sparring presumably increased their fighting experience--leading to higher rank. Simmons and Scheepers (1996) assert that the disproportionately large necks of giraffe have evolved due to selection pressure for males with heavy necks and heads. According to this hypothesis, the males with the heaviest necks and heads should have the highest reproductive success. In fact, Pratt and Anderson found that the highest-ranking males were able to court the most females, when rank was based on size of neck and development of ossicones. Thus, the sexual selection of large necks among giraffe is a reasonable possibility.
Displacement occurs as the result of male competition for estrous females (see mating system), as dominant males immediately displace subordinates from the presence of potentially receptive females. Displacement interactions typically involve the dominant male intently staring at, or walking toward, the less dominant male, who then runs away; typically, there is no need for physical contact between males. Very rarely, displacement attempts end in fighting. Pratt (1985) saw displacement as the hallmark of dominance among male giraffe. Of 129 displacements observed by Pratt, only four of the displacing bulls were Class C bulls; the rest were A or B. Further, in almost all instances, a more dominant male displaced a less dominant one. Thus, a male's ability to displace another seems to depend on his social rank.
In addition to building a dominance hierarchy among males, necking behavior prepares male giraffes for fighting, a male-male activity that is similar in content to sparring but much more fierce. Fighting is relatively rare among giraffe, but has been observed by many scholars, typically in the presence of females (Leuthold 1979). Fighting was observed only twice by Pratt (1985), once in the presence of an estrous female and once in the absence of any females. Fighting encounters between male giraffe are typically abrupt and violent. The mechanisms of fighting are similar to those found in necking--males exchange blows by striking one another with their heavy necks and heads. The main difference between fighting and sparring is intensity and risk: injuries from fighting are much more common, since individuals simultaneously and recklessly pound one another rather than taking turns delivering gentle blows, as observed in sparring (Leuthold 1979; Pratt 1985).
Male-female interactions in giraffe are mostly limited to mating interactions. Common male-to-female interactions include sniffing genitalia, urine testing, flehmen behavior and courtship/guarding. Female-to-male interactions often consist of females rubbing their necks against the flanks of males (Dagg 1976). For more details on giraffe mating behavior, see mating system.
Females with young tend to associate with one another for selfish herd reasons, in the nursery groups and calving pools that characterize their parental care. Other than casual greetings and haphazard aggregation, female giraffes have few interactions with one another (Leuthold 1979; Pratt 1985).
A group of females and young.
Females associate with one another mainly for convenience and selfish herd reasons.
Image taken with permission from http://randm2.tripod.com/index.html
Young giraffes are considered calves for the first year and a half of their lives, when they associate with their mothers for nursing and parental care. At the age of a year and a half, they are classed as subadults, and at 5 years, when they reach sexual maturity, giraffes are considered adults (Leuthold 1979; Le Pendu 2000).
Calves exhibit the most frequent social interactions observed among giraffe. At ages as early as one week, they are left by their mothers in calving pools with other calves of similar age. Within these groups, giraffe calves experience much of their socialization through physical contact with their peers. Pratt (1982) lists a few common calf-calf interactions: "nosing, rubbing, sniffing, licking, kicking, gamboling, and 'naso-frontal greeting'." These kinds of contact are most common in young calves of less than a year old. Leuthold (1979) noted that young males began playfighting at ages younger than one month, and that groups of calves would often run and jump playfully together.
Several authors, including Leuthold (1979) and Pratt (1985), note that calves exhibit the highest levels of inter-individual bonding among giraffe. Calves may associate with the same few peers for several months at a time during their infancy. Pratt (1982) found that calves were found in stable peer groups of the same two to four individuals in 48-92 percent of their sightings, and that they spent even more time with these peers than with their own mothers. In fact, groups with mothers and calves are the most stable group type observed among giraffe, most likely because these groups give the calves some degree of predator protection (see calving pools), as well as providing social stimulation.
The most significant adult-young relationship is that of the cow and her calf. To learn more about the cow-calf bond, see parental care.
Adult giraffes of both sexes tend to act curious towards calves, often approaching, sniffing and nosing them. Pratt (1979) points out that giraffes use olfactory cues to recognize one another, and that adults may use olfaction to familiarize themselves with newborn calves.
Adult giraffes are naturally curious towards young, approaching and often touching them.
Image taken with permission from Hedweb
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