A study of birds on the pull has shown that in many cases personality really does trump looks.
Researchers found that adventurous female zebra finches tend to prefer the most out-going and confident males. They seem to be less impressed by a prospective partner's body size, condition or beak colour.
Scientists conducted "personality tests" on more than 150 birds, assessing males and females separately.
In particular, they measured levels of exploratory behaviour by watching birds' willingness to investigate new environments and their reaction to new objects. Each female was then shown a pair of brothers exploring strange cages.
One of the male birds was made to appear less exploratory than the other by restraining it in a box not visible to the female.
The female was then placed together with the brothers to see which one she appeared to be most attracted to.
Females with exploratory personalities chose to spend more time with males who seemed the most outgoing, irrespective of their appearance.
Less outgoing females showed no preference for either male.
The findings were published in the journal Ethology.
Study leader Dr Sasha Dall, from 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."
Co-author Dr Wiebke Schuett, from the Royal Veterinary College, said: "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.
"However, this is the first evidence that the personality of both partners plays a role in mate choice."