Ruby-throated hummingbirds are one of the most familiar backyard birds in eastern North America. With their bright emerald green backs, gray-white undersides, and of course, ruby red throats on the males, ruby-throated hummingbirds are a colorful sight at feeders and in gardens from spring through fall.
Do male and female ruby-throats look different?
Yes, male and female ruby-throated hummingbirds have different plumage colors. Adult male ruby-throats have a brilliant metallic red throat patch (called a gorget) that can appear black in low light. Females lack the red throat patch and are duller overall, with a pale throat that is whitish towards the chin. Both sexes have green backs and heads, but the green is brighter on the males. The undersides are grayish-white on females and whiter on males.
Do ruby-throats change color seasonally?
Ruby-throated hummingbirds do undergo some seasonal color changes, but they are subtle. In fall and winter, the bright throat patches and emerald green backs of the males become slightly duller. The feathers may become worn and frayed as well. Females and young birds also look a bit duller in the nonbreeding season. These color changes are likely due to differences in diet between the breeding grounds and wintering grounds. Flower nectar contains carotenoids – pigments that produce orange, yellow, and red colors. Less availability of flower nectar in the winter means less vibrant colors.
Do the throats change color?
The ruby red gorget of the male is permanently colored – the feathers do not change to another color later. The throat patch becomes a bit duller outside of breeding season, but it does not turn a dramatically different shade. Females may sometimes show just a small amount of red at the throat as they age, but they never acquire a full red patch like the males.
Do molting and juvenile plumage cause color changes?
Ruby-throated hummingbirds molt once per year, in late summer/early fall after breeding. During the molt, they gradually replace all of their feathers over a period of a month or two. The new feathers will be bright and vibrant for the migration to the wintering grounds. Juvenile ruby-throats have drab brownish plumage, lacking any iridescent colors, and resemble the adult female. As they molt and replace feathers, the brilliant red, green, and gray colors will emerge. So during the late summer months, you may see some drabber looking individuals that are young birds growing in their adult plumage.
Summary of ruby-throat seasonal color changes
- Males have brighter plumage during the breeding season.
- In winter, plumage of both sexes becomes somewhat duller looking.
- The red throat patch on males does not change to another color.
- Females may show just a small red throat patch as they age.
- Young birds lack bright colors until their first molt.
Do any other North American hummingbird species show dramatic seasonal color changes?
Most hummingbird species in North America do not undergo major seasonal color changes. However, adult male rufous hummingbirds do display a striking difference. In breeding plumage, male rufous hummers have bright rusty red plumage on their backs and flanks, and an orange throat. In nonbreeding plumage, they molt into a green-backed appearance with a white throat that resembles a female.
Rufous hummingbird breeding plumage
- Brilliant rusty reddish-orange plumage on back, rump, and flanks
- Orange throat patch
Rufous hummingbird nonbreeding plumage
- Green back
- Pale whitish throat
This dramatic color change appears to be an adaptation to compete for breeding territory and attract females in spring and summer. During the nonbreeding season, the green plumage provides better camouflage.
Do hummingbirds undergo color changes as juveniles?
Yes, hummingbirds can look dramatically different as juveniles compared to adults. Hatchlings are almost featherless, but start growing identifiable feathers within a couple weeks. Here are some examples of how appearances change:
Ruby-throated hummingbird
- Hatchlings: Tiny, nearly naked body with some gray down
- Juveniles: Grayish-brown overall, drab white underside
- Adult females: Emerald green back, white underparts with gray sides, pale throat with some red
- Adult males: Brilliant metallic green back, clean white underparts, vivid ruby red gorget
Rufous hummingbird
- Hatchlings: Lightly covered in downy feathers
- Juveniles: Spotted brownish-green plumage
- Adult females: Green above, buffy white below with rusty flank spots
- Adult males: Rufous coppery red back, orange throat
The drab juvenile plumage provides camouflage in the nest before they are strong flyers. As they grow and molt, the vibrant red, orange, green, and iridescent coloring develops.
Why don’t females have bright colors like the males?
In most hummingbird species, the males have the most vibrant and showy plumage. There are a couple of theories as to why:
- Bright colors in males help attract females and intimidate competing males in breeding displays.
- Dull plumage in females provides better camouflage while incubating eggs and brooding young in the nest.
- Bright colors may be an indicator of fitness in males. Females carefully select healthy mates.
- Females spend more time and energy on nesting activities than males, so they may have less energy to devote to growing colorful feathers.
Having one brightly colored sex and one camouflaged sex may provide the best balance for the species in terms of attracting mates, brooding young successfully, and avoiding predators. The tendencies are not absolute though – a few hummingbird species do have females with colorful plumage similar to males.
Do diet and habitat impact hummingbird colors?
Yes, a hummingbird’s diet and habitat can influence its plumage colors. Here’s how:
- Carotenoid pigments from flower nectar enhance reds, oranges, and yellows.
- Iridescent feather colors come from light refraction off microscopic structures.
- Molting grounds with abundant flowers boost bright colors.
- Adequate protein from insects helps grow colorful new feathers.
Habitats with more flowers and arthropod prey, such as tropical areas, support the most vibrantly colored hummingbirds. Birds restricted to poorer quality wintering grounds often appear duller until they return to flower-rich breeding areas.
How do ruby-throats display their colors in courtship?
Male ruby-throated hummingbirds use their vibrant plumage in courtship displays to attract females:
- Aerial displays – Males fly in loops and dives to show off their colors.
- Perch displays – Males puff up feathers and turn to showcase their throats.
- Chase displays – Males chase females, showing their colors.
In these displays, the males orient themselves to best exhibit the ruby red throat to the females. The bright plumage signals health and fitness as a mate. Females watch the displays to select a healthy male with a territory to provide food.
Conclusion
While ruby-throated hummingbirds retain their characteristic plumage year-round, they do undergo subtle seasonal color changes as well as dramatic transformations from juveniles to adults. Molting, diet, habitat, and mating displays all interact to produce their vivid colors of red, green, and iridescent feathers. Understanding the factors that drive hummingbird colors provides a deeper appreciation of their beauty.
