Homosexual behavior in sheep

Homosexual behavior in sheep is common and well documented in domestic sheep (Ovis aries) and at least four species of wild sheep (members of the genus Ovis). About 8% to 10% of domestic rams (male sheep) refuse to mate with ewes (female sheep) but do readily mate with other rams, making them the only known mammal besides humans to exhibit exclusively same-sex sexual behavior. Around 18% to 30% of all domestic rams demonstrate at least some homosexual behavior. Male domestic sheep's homosexual behavior and preference has received much academic discussion.

Several observations indicate that male–male sexual preference in rams is sexually motivated. Rams routinely perform the same courtship behaviors (including foreleg kicks, nudges, vocalizations, anogenital sniffs and flehmen) prior to mounting other males as observed when other rams court and mount estrous females. Furthermore, pelvic thrusting and ejaculation often accompany same-sex mounts by rams. Additionally, a small number of females that were accompanied by a male fetus in utero (i.e. as fraternal twins) are freemartins (female animals with intersex characteristics like being behaviorally masculine and lacking functioning ovaries).