Herd composition, kinship and fission–fusion social dynamics among wild giraffe

Abstract

A variety of social systems have evolved as a consequence of competition and cooperation among individuals. Giraffe (Giraffa camelopardalis sp.) societies are an anomaly because the dearth of long-term data has produced two polar perspectives: a loose amalgamation of non-bonded individuals that sometimes coalesce into a herd and a structured social system with a fission-fusion process modifying herd composition within a community. We analysed 34 years of data collected from a population of Thornicroft's giraffe (G. c. thornicrofti, Lydekker 1911) residing in South Luangwa, Zambia, to establish the nature of giraffe society. Our sample consisted of 52 individually recognized animals. We found that giraffe herd composition is based upon long-term social associations that often reflect kinship, with close relatives significantly more likely than non-relatives to establish herds. Mother/offspring dyads had the strongest associations, which persisted for years. Giraffe live in a complex society characterized by marked flexibility in herd size, with about 25% of the variance in herd composition owing to kinship and sex. We suggest that giraffe herds share many characteristics of fission-fusion social systems and propose that sophisticated communication systems are a crucial component regulating subgroup dynamics. caractéristiques des systèmes sociaux de fission-fusion et nous proposons que les systèmes de communication sophistiqués sont une composante cruciale dans la régulation de la dynamique des sous-groupes.

Social Preferences of Translocated Giraffes (Giraffa Camelopardalis Giraffa) in Senegal: Evidence for Friendship Among Females?

“…If social preferences are consistently maintained over time, then they are considered relationships (Whitehead et al, 2005). We compared the levels of associations between giraffes in the Bandia reserve, with those reported for captive and wild giraffes residing in fission-fusion social systems (Bercovitch and Berry, 2012). According to the recorded AIs, we classified dyads into three categories: weak relationship (AI range 0 -0.2), medium relationship (AI range 0.2 -0.4), and strong relationship (AI range 0.4 -1).…”

“…In small herds strong associations developed among adult females (Fennessy, 2009). Recent studies reported that female giraffes showed significant preference for, or avoidance of, other giraffes (Bercovitch and Berry, 2012). In the wild, female giraffes form a stable population of individuals that is divided into geographically distinct subgroups, despite the absence of physical barriers (Carter et al, 2013b;van der Jeugd and Prins, 2000).…”

“…This system evolved in response to the exploitation of food availability that animals can most effectively use by broadcasting long-distance information to their kin. This is combined with short-distance bonding mechanisms (Bercovitch and Berry, 2012). Social ties in giraffe society could be influenced by kinship and social attraction or may only associate because they have similar habitat preferences (Carter et al, 2013a;Carter et al, 2013b).…”

Personalities, social patterns, and reproductive success in female eastern grey kangaroos (Macropus giganteus)

“…elephants, Archie et al 2006), and relatedness sometimes does not explain association strengths at all, as in big brown bats (Eptesicus fuscus) (Metheny et al 2008). In a number of social ungulate species with higher fission-fusion dynamics, including bison (Bison bison) , wild boar (Sus scrofa) (Kaminski et al 2005), red deer (Cervus elaphus) ) and giraffe (Bercovitch and Berry 2013), mothers continue to associate to some degree with their female offspring following weaning. These associations can persist when daughters reach adulthood in some species, for example mountain goats (Oreamnos americamus) (Godde et al 2015).…”

“…Such associations have been reported in some bat species Kerth et al 2011), Grevy's zebra (Equus grevyi) ), chimpanzees (Langergraber et al 2009), bottlenose dolphins (Tursiops spp.) (Frère et al 2010b), eastern grey kangaroos (Macropus giganteus) ), and giraffe (Giraffa camelopalardis) (Bercovitch and Berry 2013;). The strongest associations within a higher fission-fusion social context often occur between relatives, especially among females where female-biased philopatry occurs.…”