Nightly selection of resting sites and group behavior reveal antipredator strategies in giraffe

Do giraffes sleep while others keep watch? At evening resting sites in Namibia, some animals remained standing and scanning their surroundings while others lay down, sometimes curling their heads back onto their flanks. That vulnerable-looking posture raised the possibility that group life helps giraffes balance rest with remaining alert.

Anna Lena Burger, Julian Fennessy, Stephanie Fennessy and Paul Dierkes used night-vision and thermal cameras on 24 nights during dry and wet seasons. Their study followed Angolan giraffe groups on a partly fenced ranch, recording the early hours of darkness and inspecting resting sites the next day. They recorded 152 head-on-flank bouts, the posture commonly used as an indicator of possible rapid-eye-movement sleep.

At least one giraffe remained vigilant during all observation periods, and several animals rarely adopted the curled posture simultaneously. Resting sites offered relatively open views among scattered trees or low bushes. The pattern fits a protective role for group vigilance, but does not demonstrate organised guard shifts; brain activity was not measured, and no free-ranging lions lived at the site. The observations reveal how resting and alertness can coexist within one giraffe group, without showing that its members consciously take turns.