In the animal kingdom, bright, flashy colors are often associated with males trying to attract mates. However, in some species of birds, it is actually the females that have the colorful, decorative plumage while the males are drab and inconspicuous. The phenomenon of females being more colorful than males is known as reverse sexual dimorphism. There are several evolutionary reasons why this occurs in certain bird species.
Reasons for Reverse Sexual Dimorphism in Birds
There are a few key factors that can lead to females being more colorful than males in bird species:
- Female-female competition – In species where females take on multiple mates, there is increased competition among females over access to males. The more colorful, flashy females may have an advantage in attracting male attention.
- Male mate choice – In some species, males take on the role of choosing among potential mates. Again, more colorful females are selected for by choosy males.
- Camouflage for nesting – Drab male plumage allows for better camouflage while nesting and caring for young. Colorful females can still attract mates.
- Species recognition – Bright female plumage allows for easier species recognition, especially among closely-related bird groups.
The relative importance of each factor depends on the mating system and natural history of each particular species exhibiting reverse sexual dimorphism.
Bird Groups with Colorful Females
There are a several families and species of birds where females tend to be more colorful and decorative than their male counterparts:
Birds of Paradise
This family is famous for their wildly elaborate plumage and mating rituals. In birds of paradise, females are typically drab brown and black while males sport brightly colored feathers, plumes, and ornamentation used in courtship displays. However, there are a few species where the females have distinctive ornamentation:
- Twelve-wired Bird of Paradise – Females have yellowish plumage on their breasts and necks.
- Ribbon-tailed Astrapia – Females have glossy black plumage and long tail ribbons.
- Princess Stephanie’s Astrapia – Females have iridescent green shoulder patches and small head tufts.
In these species, elaborate female plumage and ornaments likely evolved for mutual mate choice and species recognition.
Phalaropes
Phalaropes are shorebirds that exhibit a complete role reversal from typical avian sex roles. Females are larger and more colorful than males. They compete for access to mates, defend territory, and leave the male to incubate the eggs and care for the young. Examples include:
- Red-necked Phalarope – Breeding female has gray plumage with deep red neck and breast.
- Wilson’s Phalarope – Female has pale gray plumage with rich red-brown throat and breast.
- Red Phalarope – Female is reddish-brown with black markings on back and chest.
The male phalaropes are more drab gray-brown. The female’s bright plumage likely allows males to identify potential mates.
Other examples
Here are a few other bird species where the female is more colorful than the male:
- Eclectus Parrots – Females are bright red and purple, males are green.
- King Penguins – Females have bright orange neck and breast plumage.
- Black Swans – Females sometimes develop black plumage with white flecks, males are gray-brown.
- Spotted Sandpiper – Females have bold spotted plumage, males are plain gray.
Why Be Drab?
If bright colors give females an advantage, why are many male birds dull and cryptic looking? Here are some of the benefits of camouflaged male plumage:
- Avoid predation – Drab males blend in better while incubating eggs and caring for nestlings.
- Conserve resources – Producing fancy feathers and colors may use resources and energy better spent on mate competition by the females.
- Paternity assurance – Cryptic males can’t fake bright female plumage, ensuring they don’t expend parental care on another male’s offspring.
Natural selection seems to favor subdued male plumage in species where it provides an advantage. Females get to keep their showy feathers for attracting mates.
Conclusion
While males with flashy plumage get most of the attention, in some bird species, it is actually the females that evolved extravagant colors and adornments. This reverse sexual dimorphism can occur due to female competition, male mate choice, the need for camouflaged nesting, or species identification. Groups like birds of paradise, phalaropes, and eclectus parrots all have species where the females are distinctly more colorful than their male counterparts. Drab male plumage likely persists in these species because it aids in predator avoidance, conserving resources, and ensuring males care for their own offspring. So while the males may not be as spectacular, they play an important role in breeding success. Next time you see a vivid flash of feathers, take a second look – it just might be a fancy female!