(Newser) – Add one more creature to the list of animals known to engage in oral sex: A pair of male brown bears living in captivity in a sanctuary in Croatia have been observed engaging in fellatio regularly over the six years they were studied, report researchers in the journal Zoo Biology. In fact, the researchers go into considerable detail—suffice it to say that fellatio looks in bears much like it does in humans, tends to take a few minutes, and happens several times a day, reports Discover. The researchers also noted that, over the course of 100-plus hours of observation, one bear was always the one to both initiate and perform the sex act on the other. They say it's the first time fellatio has been observed between bears living in "proper conditions."

In their study they write that "in solitary species ... sexually stimulating behaviors that are not linked to reproduction ... are more enigmatic, and possibly indicative of something abnormal." But the researchers have a theory that might explain the behavior: They wonder if both bears being orphaned at a young age might play a role, since other orphaned bears have been observed sucking their own or their sibling's paws, ears, and other body parts in an apparent attempt to self soothe. As unusual as the behavior may be in bears, they are not alone in the animal kingdom: Bonobos, female cheetahs and lions, and Chinese fruit bats have all been observed performing oral sex, reports LiveScience. (Click to read about another unusual sex-related animal discovery.)

