When no females are around, male Japanese termites pair up to make homosexual nests together, new research has revealed. However, while these civil partnerships can be happily maintained for long periods of time, if given the chance these gay termites will readily kill a heterosexual male in order to mate with his partner.

Same-sex courtship has been observed in a number of animal species, although the reasons behind this are poorly understood, given that this type of behavior would seem to be detrimental to the survival of a species. However, writing in the journal Animal Behaviour, the study authors report that forming all-male couples actually brings a number of survival benefits to termites.

When conducting their experiments, the researchers placed male termites together in makeshift colonies under lab conditions, noticing that once they realized no females were available, they readily formed all-male couples, settling down to nest together.

Explaining this behavior in a statement, study co-author Nobuaki Mizumoto said that “male termites aren't able to survive on their own, but those that make nests with another male survived for much longer.” This, he says, is partly down to the fact that searching for females places male termites in danger of being caught by predators, and partly because single termites are unable to groom themselves and need a partner to keep them clean and free of rotting wood, which can be detrimental to their health.

However, when the researchers placed all-male colonies in close proximity to mixed-sex colonies, they found that the two sometimes became connected as the insects tunneled towards each other. When this occurred, males in homosexual couples regularly killed heterosexual males and mated with their partners. However, only one male from a gay couple was able to mate with this stolen female, indicating that the homosexual unions broke down as soon as females became available.

In other words, as Mizumoto explains, “pairing with another male isn't the best option, but it gives mateless termites a chance to survive until they find a female, if that happens at all.”