Red-billed Oxpecker With A Giraffe

Male giraffes often engage in necking, which has been described as having various functions. One of these is combat. Battles can be fatal, but are more often less severe, generally ending when one giraffe surrenders to the other. The longer the neck, and the heavier the head at the end of the neck, the greater the force a giraffe is able to deliver in a blow. It has also been observed that males that are successful in necking have greater access to estrous females, so the length of the neck may be a product of sexual selection.
After a necking duel, a giraffe can land a powerful blow with his head — occasionally knocking a male opponent to the ground. These fights rarely last more than a few minutes or end in physical harm.
Another function of necking is sexual, in which two males caress and court each other, leading up to mounting and climax. Such interactions between males are more frequent than heterosexual coupling. In one study, up to 94% of observed mounting incidents took place between two males. The proportion of same sex activities varied between 30 and 75%, and at any given time one in twenty males were engaged in non-combative necking behaviour with another male. Only 1% of same-sex mounting incidents occurred between females.