^ What I just borrowed from the library.
A good example of the difference between behavioral transvestitism and homosexuality is in the Bighorn Sheep. In this species, males and females lead almost entirely separate lives: they live in sex-segregated herds for most of the year and come together for only a few short months during the breeding season. Among males, homosexual mounting is common, while females do not generally permit themselves to be mounted by males except when they are in heat (estrus). A small percentage of males, however, are behavioral transvestites: they remain in the female herds year-round and also mimic female behavioral patterns. Significantly, such males also generally refuse to allow other males to mount them, just the way females do. Thus, among Bighorn Sheep, being mounted by a male is a typically “masculine” activity, while refusal of such mounting is a typically “feminine” behavior. Males who mimic females specifically avoid homosexuality. This is the exact opposite of the stereotypical view of male homosexuality, which is often considered to be a case of males “imitating” females. It is also a striking reminder of how important it is not to be misled by our preconceptions about human homosexuality when looking at animals.