Leaving home seems to require going somewhere else. For a giraffe, however, home can mean both a familiar area and a familiar community. If different communities use overlapping country, a young animal could change its social world while remaining close to where it grew up.
Monica Bond and colleagues found evidence of exactly that possibility in northern Tanzania. Seven years of photographs allowed them to follow 137 young giraffes and ask two separate questions: how far did each move, and which adult female community did it associate with? Some changed community without making a large spatial shift. Their 2021 study showed why a map of movement alone can miss a consequential part of growing up.
A community is larger than the group visible today
Giraffe groups split and merge. The animals feeding together on one survey need not all remain together the next day. That flexibility makes permanent social membership harder to recognise than it would be in a small, stable troop.
The researchers therefore built the social map from repeated associations among adult females. These records revealed broader communities within which temporary groups formed. A young giraffe’s community could then be assigned from the adult females accompanying it, rather than from an assumption that any single observed group was its permanent herd.
The distinction is crucial. Joining a new temporary group within the same community is an everyday change. Repeatedly associating with a different community, without subsequently returning to the original one in the records, is a larger social transition.
The field team conducted 42 photographic surveys from 2012 to 2018. Individual spot patterns connected sightings across years. For the dispersal analysis, an animal had to be first recorded as a calf and seen repeatedly over at least five years. That left 67 males and 70 females from 328 calves born in the first two years of the project.
This requirement provided long enough histories to distinguish some lasting shifts from brief visits. It also means the sample represents animals that survived and remained detectable for long enough to qualify; it is not a complete record of every calf’s eventual destination.
Separating distance from membership
The authors classified four possible outcomes: staying near the original location and community; changing community while staying nearby; moving farther while retaining the community; or changing both location and community.
“Nearby” did not mean standing still. Spatial dispersal was assessed against a distance threshold based on the radius of the average adult female home range in the animal’s natal community. The team also examined the sequence of sightings, so a brief excursion followed by a return would not automatically count as a permanent move.
That leaves room for an animal to walk several kilometres and still be classified as a social-only disperser. The term describes a change small relative to the familiar female range, not an absence of movement.
Social dispersal likewise required interpretation across time. A giraffe seen with another community and later back with its original one was treated as having explored. An animal that shifted and was subsequently seen only with other communities was classified as a social disperser. The study thus used location and association histories together to ask whether a transition appeared to persist.
Sixteen animals changed community without a large move
The broad sex difference was substantial. Forty-six of the 67 males dispersed in some form, compared with 18 of the 70 females. Most females remained near their original area and within their original community.
Among the dispersers, 12 males and four females changed community without crossing the study’s spatial-dispersal threshold. Those 12 males constituted about a quarter of the males that dispersed—not a quarter of every male in the sample. A further 26 males and five females changed both their spatial location and social community.
The opposite combination also occurred: eight males and nine females moved beyond the threshold while remaining associated with their original female community. This is particularly informative because it shows that the two measures were not simply different labels for the same event. A giraffe could move a considerable distance without severing its recorded community membership, or change membership without a similarly large displacement.
The finding opens a plausible biological explanation. Joining a neighbouring community might give a young male access to different potential mating partners while preserving knowledge of familiar food, water and routes. But the study did not establish paternity or measure the genetic relatedness of each community. Avoiding inbreeding and reducing travel costs remain explanations for the pattern, not demonstrated benefits enjoyed by the 16 social-only dispersers.
Growing up has several social stages
A separate study of adolescents in two Kenyan populations found that young giraffes repeatedly associated most strongly with adolescents of their own sex. That project compared association patterns over nine months at each site; it did not follow the same animals through a complete dispersal history.
The two approaches illuminate different parts of social development. Adolescents can maintain selected peer relationships, while longer records reveal whether their wider community changes. Strong associations during one life stage do not by themselves establish where an animal will eventually settle.
The Tanzania study also found that animals born closer to towns tended to disperse shorter distances and later. Several explanations remain possible, including barriers to movement, habitat differences or undetected departures beyond the study boundary. The result should not be simplified into a universal claim that proximity to people either drives giraffes away or keeps them contentedly at home.
Even the observed social departures retain uncertainty. Nine of the 47 giraffes classed as social dispersers were seen only once with a new community and never detected again. Some could have been making late exploratory visits. And additional years might reveal dispersal among young males still classified as non-dispersers when observations ended.
Those limits do not erase the distinction the study uncovered. They explain why dispersal needs a history, rather than a single distant sighting. For a social animal living among overlapping communities, the question “Where did it go?” becomes more informative when accompanied by “Who did it join?”
Sources
- Monica L. Bond, Derek E. Lee, Arpat Ozgul, Damien R. Farine and Barbara König (2021). “Leaving by staying: Social dispersal in giraffes.” Journal of Animal Ecology 90, 2755–2766. Full paper.
- Zoe Muller, Innes C. Cuthill and Stephen Harris (2022). “Adolescence and the development of social behaviour in giraffes.” Mammalian Biology 102, 1333–1343. Related study.
