Koala (Phascolarctos cinereus) are one of the most popular symbols of Australia, and despite their being considered bears, they have nothing to do with the true bears, they are real marsupials, related to kangaroos or more precisely to possums.

They are indeed peculiar with their adaptations to arboreal life and the diet formed almost exclusively by the toxic and less nutritious eucalyptus leaves.

Now researchers at the University of Queensland, investigating a population of 130 captive koalas, add another freak to their biology: female koalas enjoy lesbian "sex sessions", rejecting male suitors and trying to mate with each other, sometimes up to five at a time, as researchers have noticed in a new research. This tendency was observed till now only in individuals kept in captivity, while in the wild, they seem to remain heterosexual.

The researchers detected this behavior using digital cameras installed in the cages of the koala. They found a ratio of three homosexual mating sessions for each heterosexual one. "Some females rejected the advances of males that were in their enclosures, only to become willing participants in homosexual encounters immediately after," explained the research team. "On several occasions more than one pair of females shared the same pole, and multiple females mounted each other simultaneously. At least one multiple encounter involved five female koalas."

The researchers tried to explain the bizarre behavior: lesbian sex could be used by females to turn on the males; it may also be a hormonal impairment occurring in captivity, or employed to relieve stress. "Our aim was to determine the extent of differences in the homosexual and heterosexual behavior of female koalas and thereby to determine the purpose of female homosexual behavior in the koala. Wild koalas brought into captivity clearly display homosexual behavior on a regular basis. A total of 15 heterosexual and 43 homosexual interactions were recorded in separate animals. Homosexual behavior was restricted to females only. Heterosexual encounters were typically twice as long as homosexual encounters," explained the researches.