Homosexual behavior in sheep
Behavior among sheep interpreted as homosexual / From Wikipedia, the free encyclopedia
Homosexual behavior in sheep has been well documented and studied. The domestic sheep (Ovis aries) is the only species of mammal except for humans which exhibits exclusive homosexual behavior.[1][2][3] "About 10% of rams (males), refuse to mate with ewes (females) but do readily mate with other rams."[2] Thirty percent of all rams demonstrate at least some homosexual behavior.[4] One report on sheep found that 8% of rams exhibited homosexual preferences—that is, even when given a choice, they chose male over female partners.[5] This documented homosexual preference has garnered much discussion.[10] Such rams prefer to court and mount other rams only, even in the presence of estrous ewes.[1] Moreover, around 18–22% of rams are bisexual.[7]
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.[9] The Merck Manual of Veterinary Medicine lists homosexuality as a "normal behavior" in up to 30% of all rams in its section on behavioral problems.[4] 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 lack functioning ovaries).[15]