Male Japanese quail were raised with normal brown-colored quail and should have imprinted on brown females as mates.

Their preference for mates were then measured by how much time they spent by a window with females on the other side.

• Phase 1: adult males saw a blond female on the other side of a window followed by chances to mate with her.

• Phase 2: they saw a brown female through the window, but were not allowed to mate with her.

• Phase 3: they showed a strong preference for blond (B) over normal brown (N) females.