SCARLET? TANAGER - This female Scarlet Tanager shows none of the bright scarlet color that gives the species it's name. Tanagers are strongly sexually dimorphic - the males and females look different - and recent studies show that this is linked to migration. More than three-quarters of migratory species are dimorphic, while over three-quarters of sedentary species are not. With migration, sexual roles diverge and in order to establish a breeding territory in a few days, the female must select a mate. The most attractive males are more likely to be chosen and quickly - which drives the evolution to more showy plumage in the males.