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

Abstract

The size of adult male giraffes (Giraffa giraffa angolensis) far exceeds the size of the females. At the Namutoni waterholes in Etosha National Park, bulls were seen many times each day screening adult females for their pending sexual receptivity by provoking them to urinate; this mainly involved sniffing their genitalia. If the female accedes to the male’s invitation, she widens her hindleg stance, braces her body, and then urinates, usually for at least five seconds. The male places his muzzle and tongue in the urine stream, and then performs flehmen, often raising his head high in the air. Males never investigated urine on the ground. The bilateral papillae on the giraffe’s hard palate connect with the nasopalatine ducts, which enter the bilateral vomeronasal organ (VNO). Unlike many mammals, the giraffe’s VNO lacks a prominent connection to the nasal cavity and its connections to the oral cavity are primarily via the incisive papillae. Most days, some giraffes were observed searching for bones for extended periods, chewing them, and sometimes being troubled by a bone stuck in their mouth. A giraffe killed by lions was frequented for several days by a procession of giraffes investigating the carcass. A very dark-colored bull giraffe emitted loud pulsed growls that drove off most of the surrounding giraffes.