In most marsupials and placental mammals such as the primates, perissodactyls and elephants, as well as many rodents and artiodactyls, females ovulate ‘spontaneously’, meaning that ovulation proceeds in the absence of copulation. However, in certain species, such as rabbits, cats, and ferrets, stimulation provided by the male partner during mating is required to trigger the pre-ovulatory LH surge and thus to induce ovulation. Often, tactile stimulation during mating triggers ovulation, but in certain cases chemical cues, present in the semen, stimulate the LH surge. Examples of this latter type occur in members of the Family Camelidae, which includes the llamas and alpacas, as well as the dromedary and the bactrian camel.