They say the beauty is in the eyeball holder. For male rainbow finches, that's definitely right, has in right eye. The birds depend on their right eyes for scoping out potential mates. Many males are choocing when picking partners and the rainbow ingudio finch is no acception. Some birds with colorfurl and variable plumage goaled in a male tend to go for a gal with a pretty face, one that pretty match is. So male with black faces prefer the females with the same. But that bias turns out depends how they look at. When researchers gave black face finches a choice, they could flirt with black females, red face females or fellow male. Males with both eyes open cozy to the dull with dark feathers. But when researchers covered the male's  right eye, the male sing and dance with everyone, or hopped up randomly looking lost. You can use either eyes to see the finding in the journal Biology Letters. The right eye feeds and folds the left half of the brain, so it seems males are really particular when it comes to choosing a partner are not in their right minds.