Flehmen, Osteophagia, and Other Behaviors of Giraffes (Giraffa giraffa angolensis): Vomeronasal Organ Adaptation

Male giraffes collect female urine directly in their mouths. The collection is part of courtship: a male investigates a female, sometimes nudging her, and catches urine with his muzzle and tongue when she releases it. He then often curls his upper lip and raises his head, a response called flehmen that helps mammals assess chemical signals.

Lynette A. Hart and Benjamin L. Hart recorded giraffes at waterholes in Namibia's Etosha National Park during visits in 1994, 2002 and 2004, totalling 153 hours of observation. They also examined two anatomical specimens to investigate the route from the mouth to the organ that detects reproductive chemical cues.

Across 102 recorded investigations of adult females, the observers noted fifty-four urinations and fifty-one male flehmen responses following them. They never saw males sample urine from the ground. The specimens had clear connections from the mouth to the sensory organ but only a very small nasal connection. Together, behaviour and anatomy suggest a way of testing females without lowering a heavy head to the ground; the study did not directly measure which chemicals were detected. The female's cooperation, including bracing her hindlegs before urinating, is part of making that close-range test possible.