Social organization and behaviour of giraffes were studied in Tsavo East National Park, Kenya, by means of road strip counts and observations of individually known animals.
Most groups comprised of one to ten animals, with a maximum of thirty‐five and a mean of 3.8. Group size and composition varied locally to some extent. Single adult males constituted the commonest group type; in groups of two or more animals the sexes were usually mixed. Groups were loose and open; close inter‐individual bonds were only temporary and occurred mainly in young animals.
Home ranges of adult males overlapped extensively; there was no evidence of territoriality. Subadult males were gregarious and often indulged in playfighting, while adult males were often seen alone, rarely interacting and never fighting. An absolute hierarchy among them was most evident in the presence of an oestrus female. Three behavioural categories, probably correlated with age, could be distinguished in adult males. Some aspects of sexual behaviour are described.
Calves commonly formed crèche groups; they were temporarily separated from their mothers for up to 1 km during the daytime. They continued sucking up to the age of 13 months and remained associated with their mothers for another 2–5 months.
Comparison with other studies shows that, apart from group size, social organization and behaviour of giraffes are similar in the different subspecies and in different areas.