Why giraffe sex is a tall order and hinges on pee

With no set breeding season or visual cues, giraffe romance is difficult to navigate.
Two giraffes on a sunny day with one looking directly at the viewer.

Two giraffes on a sunny day. Deposit Photos

As Valentine’s Day quickly approaches, it’s crunch time for finding the perfect way to express love. Showing your affection for that special someone can be pretty tough for humans— but it is tricky for giraffes too. The mammals are known for their long necks, but not so much for their necking.

Unlike dogs and cats that go into heat or peacocks that use a flourish of feathers to attract a mate, giraffes do not have mating calls or visual cues to indicate that they are ready to have sex. 

[Related: Trilobites may have jousted with head ‘tridents’ to win mates.]

What they do have are nudges, pheromones, and pee. A new study published February 8 in the journal Animals has some fresh knowledge of the sex lives of giraffes and how their unique anatomy supports reproductive behavior. 

To test and see if a female giraffe is ready, males sniff their genitalia and nudge it to get them to pee. If she is open to his advances, the female will widen her stance and urinate for a few seconds while the male takes some of  the pee in his mouth. The male will then perform an action called flehmen where he curls his lip and inhales with an open mouth, transporting the female’s scent and pheromones from the male’s oral cavity to the vomeronasal organ, an organ that influences social and mating behavior.

This new study provides a precise understanding of how flehmen occurs with giraffes’ anatomy.

Flehmen is common among many animals, such as horses and cats, but most mammals will wait until the urine is on the ground to investigate it. With their tall frames, giraffes aren’t built to do this kind of exploration. 

“They don’t risk going all the way to the ground because of the extreme development of their head and neck,” said co-author Lynette Hart, a University of California, Davis professor of population health and reproduction, in a statement. “So they have to nudge the female, effectively saying, ‘Please urinate now.’ And often she will. He has to elicit her cooperation. If not, he’ll know there’s no future for him with her.”

A male giraffe begins the lip-curling flehmen behavior as the female begins to urinate. CREDIT: Lynette Hart, UC Davis.

Hart and her co-author and husband Benjamin Hart, witnessed this behavior during research trips to Etosha National Park in Namibia, a mixed habitat sanctuary that is also home to elephants, endangered black rhinos, leopards, and over 340 bird species. 

[Related: 7 animal mating rituals that make horseshoe crab orgies look tame.]

Previously, Benjamin had studied how flehmen behavior worked within the anatomy of goats and other animals. While on a trip to East Africa, the team suspected that a similar process was underway in giraffes.

“This is part of their reproductive behavior,” said Benjamin Hart, who is also a professor emeritus with the UC Davis School of Veterinary Medicine, in a statement. “This adds to our understanding of what giraffes are doing as they accumulate around a water hole. People love watching giraffes. I think the more the public understands about them, the more interested they’ll be in their conservation.”

The study also highlights some previously undocumented giraffe behaviors including chewing bones and potentially mourning their dead, after the team saw a steady procession of giraffes investigate the body of a giraffe that had been killed by two lions.