duration of copulation. Post copulation genital grooming has also been observed. Homosexuality: Same-sex sexual behaviour occurs in a range of species, especially in social species, particularly in marine birds and mammals, monkeys, and the great apes. , the scientific literature contained reports of homosexual behaviour in at least 471 wild species. Organisers of the Against Nature? exhibit stated that "homosexuality has been observed among 1,500 species, and that in 500 of those it is well documented." Genital-genital rubbing: This is sexual activity in which one animal rubs his or her genitals against the genitals of another animal. This is stated to be the "bonobo's most typical sexual pattern, undocumented in any other primate". Inter-species mating: Some animals opportunistically mate with individuals of another species. Sex involving juveniles: Male stoats (Mustela erminea) will sometimes mate with infant females of their species. This is a natural part of their reproductive biology—they have a delayed gestation period, so these females give birth the following year when they are fully grown. Juvenile male common chimpanzees have been recorded mounting and copulating with immature chimps. Infants in bonobo societies are often involved in sexual behaviour. Necrophilia: This describes when an animal engages in a sexual act with a dead animal. It has been observed in mammals, birds, reptiles and frogs. Bisexuality: This describes when an animal shows sexual behaviour towards both males and females. Extended female sexuality: This is when females mate with males outside of their conceptive period. Seahorse Seahorses, once considered to be monogamous species with pairs mating for life, were described in a 2007 study as "promiscuous, flighty, and more than a little bit gay". Scientists at 15 aquaria studied 90 seahorses of three species. Of 3,168 sexual encounters, 37% were same-sex acts. Flirting was common (up to 25 potential partners a day of both sexes); only one species (the British spiny seahorse) included faithful representatives, and for these 5 of 17 were faithful, 12 were not. Bisexual behaviour was widespread and considered "both a great surprise and a shock", with big-bellied seahorses of both sexes not showing partner preference. 1,986 contacts were male-female, 836 were female-female and 346 were male-male. Bonobo Among bonobos, males and females engage in sexual behaviour with the same and the opposite sex, with females being particularly noted for engaging in sexual behaviour with each other and at up to 75% of sexual activity being non-reproductive, as