Male gerenuks guard their mates and perform flehmen tests, or lip curl tests, by sampling the female’s urine to check for estrous.
The mating ritual of the gerenuk is complex.
When a male encounters a potential mate, the female will raise her nose into the air and pull her ears close to the head as a sign of defensiveness. Meanwhile, the male displays his horns and neck in a sideways pose. If the female is receptive, then the male will mark the female on the thigh with the contents of his preorbital gland and continue to follow her around, a form of mate guarding. As the male follows the female he continually uses his forelegs to kick the female in her thigh region.
When the female attempts to urinate, the male performs the flehmen test, or lip curl test, in which he samples her urine. Once the female comes into estrous, the male will notice the difference in the female’s urine and mating will begin.