Females choose mates for their personalities, study shows

Adventurous females choose mates with similar personalities, regardless of the male's appearance and other assets, according to research led by the University of Exeter. This is the first study to show that the non-sexual behaviour or personalities of both mates influences partner choice in non-humans.

The study focused on a population of more than 150 zebra finches. The research team assessed male and female birds separately for personality traits through a series of behavioural tests. In particular, they measured levels of exploratory behaviour through, for example, assessing birds' willingness to explore new environments and reactions to new objects. Each female then watched a pair of brothers exploring strange cages, one of which was made to look less exploratory than the other by restraining it in an invisible box. They then put the females together with the brothers they had seen and observed which male they spent the most time with.

The results showed that more exploratory females are more likely to favour the most apparently outgoing and confident males. This was regardless of the bird's body size and condition or beak colour. Less exploratory females on the other hand, did not show a preference for either male.

Team leader, Dr Sasha Dall of the University of Exeter said: "This is strong evidence that females care about the apparent personality of their male independently of his appearance. We have the first evidence that it is important for partners to have compatible personalities in the mating game. This is something we would probably all agree is the case for humans but which has been overlooked for other species."

Previous studies have shown that there is a link between a pair's personalities and their reproductive success in a range of species. Lead author, Dr Wiebke Schuett of the Royal Veterinary College said: "Exploratory females seem to have the most to gain by choosing exploratory mates. We have shown previously that pairs of zebra finches that are both exploratory raise offspring in better condition than those that are mismatched or unexploratory. Similar patterns have been seen in other birds and fish. However, this is the first evidence that the personality of both partners plays a role in mate choice."