From “Females choose mates for their personalities, study shows” (Eurekalert, August 24, 2011), we hear,
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.
Oh wait, they’re talking about zebra finches. Only 150 of them. We also learn, “This is the first study to show that the non-sexual behaviour or personalities of both mates influences partner choice in non-humans.”
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.”
Maybe. The trouble is, the researchers had restrained half of the test males in glass boxes, to make them look less adventurous. And in a situation where free form behaviour matters critically.
The hen birds could easily have been reacting to some sense that those males were caged. Just the sort of thing a bird would care about.
More generally, successful partnerships, man or bird, typically depend on complementary characteristics, as in “He says, let’s buy it; she says, let’s do the math.” Not on similarity, which leads to direct competition.