Conventional wisdom says male birds are more colorful because they are competing for female attention, and that female birds are less colorful because they need camouflage while guarding their nests. Actually, it's more complicated than that, a new study suggests.

Using computing power and new methods, researchers from New Zealand, Canada, Australia, and Germany looked at nearly 6,000 species of passerine, or perching songbirds, who make up 60 percent of the bird population. They concluded that female songbirds have evolved their own coloration to gain advantages in their particular climates and surroundings.

The study was published in Nature on Nov. 4.

Tropical birds, it turns out, are more colorful than their cousins from temperate climates probably because they do not migrate. They have the luxury of permanent homes, longer lives, and raising fewer offspring.

Tropical birds pay for these luxuries, however, by having to defend permanent territories. That’s where their bright feathers come into play—those colored feathers may help them assert control over their home turf.

In non-tropical migratory species, mating relationships are typically limited to one season, diminishing the need for color, and allowing physiological resources to be used for other efficiencies, the study concludes.

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