Around the clock: unveiling giraffe rest-activity rhythms and social dynamics

These giraffes spent almost a third of the night feeding. Their long nighttime lying periods were repeatedly interrupted by getting up and eating. A zoo visitor watching only during opening hours would miss a substantial part of that routine, along with the chance to see whether changing companions affected days and nights in the same way.

Hanna Mebus, Sebastian Schneider, Paul Dierkes and Anna Lena Burger-Schulz recorded three female reticulated giraffes at Germany's Opel-Zoo over 22 consecutive days and nights. Indoor cameras followed a sequence of group changes: two other females departed, then a male arrived. The male was separated from the females at night. The researchers measured time spent feeding, standing, walking and lying, and recorded nearby companions and social interactions.

Across the observations, feeding occupied about 28% of the defined nighttime period and lying nearly half. Nighttime activity budgets remained fairly similar across the three phases, while daytime feeding decreased and standing increased. This small, sequential study, with no coverage outside the indoor enclosure, cannot isolate a male's effect or establish a general response to introductions. It shows why a giraffe's daytime behaviour is only part of its daily life.