The social lives of giraffes—still a puzzle
- Social, but duration of social bonds not well-understood due to few longitudinal behavior studies (Bercovitch and Berry 2009a).
- Contradictory findings: "Giraffe society has been characterized as both a loose and constantly shifting amalgamation of non-bonded individuals...as well as a structured community network..." (Bercovitch and Berry 2012)
Earlier studies (VanderWaal et al. 2014 and as noted)
- Concluded temporary, non-preferential associations based on frequent, shifting group patterns (e.g., Le Pendu et al. 2000).
- However, shorter-term affiliations may not indicate a lack of social bonds (Bercovitch and Berry 2009a).
Recent studies yield new insights
- Social structures more complex than previously thought (VanderWaal et al. 2014).
- Evidence of non-random associations from a few studies
- More studies needed to draw generalized knowledge for the species (David O'Connor, personal communication)
- Multiple levels of social organization, as demonstrated using social network analysis (e.g., Bashaw et al. 2007; Shorrocks and Croft 2009; Carter et al. 2013; VanderWaal et al. 2014).
- Fission-fusion dynamics embedded within a larger structure of cliques, subcommunities, and communities.
- Do not seem to have a discernible hierarchy (may be revealed with additional studies)
- Likely, a highly fluid social structure: dynamic composition of individuals in a herd, even over short periods of time (except the mother-young bond).
- Gender, shared habitat use (home range overlap), kinship, age, familiarity, and individual social preferences and avoidances mediate association preferences (Carter et al. 2013; VanderWaal et al. 2014; Bercovitch and Deacon 2015).
- Female-female associations more common than male-male or female-male associations (Dagg and Foster 1982; Bercovitch and Berry 2012).
- Females and males often occupy different social networks; sexes sometimes segregated (VanderWaal et al. 2014).
- Female associations not random; likely make the strongest long-term associations. Males may or may not form non-random associations (Carter et al. 2013, VanderWaal et al. 2014).
- Shared space use and kinship: influence female social organization more strongly than that of males (Bercovitch and Berry 2012; Carter et al. 2013; VanderWaal et al. 2014).
- Adult males more solitary than females; often travel as singletons (Le Pendu et al. 2000; Bercovitch and Berry 2009a).
- Kin-based bonds among females: sister-sister, mother-adult daughter (Bercovitch and Berry 2012)
- Mothers observed with adult offspring of up to 10 years old
- Maternal kin of up to 3 generations
- Females very social when not guarding newborns. Usually found in congregations of other females and young.
- Some females stay in their natal areas (Carter et al. 2003).
- Subadult males tend to be part of 'bachelor herds,' usually leaving their natal area (Dagg 2014).
- Formation of all-male herds may help males learn distributions of food and females (Bercovitch and Berry 2014).
- Younger males likely follow and learn from older males.
- Possibly temporary protection against predators.
- Younger males observed in groups.
- Social cliques of younger males represent familiar individuals that are repeatedly observed together (VanderWaal 2014).
- Older males observed alone, in pairs, or with females.
- Loose herds. Group size commonly small, 3-10 individuals, but can be much larger—more than 100 individuals (Le Pendu et al. 2000; Bercovitch and Berry 2009a, 2012; VanderWaal et al. 2014; David O'Connor, personal communication).
- Mean herd size may be larger and more variable during the wet season.
- Habitat type (vegetation open vs. dense), competition within a group for food, and soil condition may also affect group size.
- Herd may be spread out over large areas.
- Because of well-developed eyesight and high head height, giraffe are able to stay in communication with one another, even if physically far apart.
- No evidence for a 'group leader'; more research needed on potential for any matriarchial structuring (VanderWaal et al. 2014).