Abstract:
The social organization of giraffes (Giraffa camelopardalis) imposes a high-cost
reproductive strategy on bulls, which adopt a ‘roving male’ tactic. Our observations on
wild giraffes confirm that bulls indeed have unsynchronised rut-like periods, not unlike
another tropical megaherbivore, the elephant, but on a much shorter time scale. We
found profound changes in male sexual and social activities at the scale of about two
weeks. This so far undescribed rutting behaviour is closely correlated with changes in
androgen concentrations, and appears to be driven by them. The short time-scale of
the changes in sexual and social activity may explain why dominance and reproductive
status in male giraffe in the field seem to be unstable.
