This reticulated giraffe is one of eight in the herd at the Oakland Zoo in California. The bull weighs 1,700 to 4,200 pounds and can be 18 feet tall. The males engage in a behavior known as necking, which is not what you think. When trying to win mating rights, two males will wildly swing and smash their heads and necks together until the weaker one either retreats or is no longer standing. It can be a vicious contest but it also ensures the best genes are reproduced.