Hummingbirds are known for their iridescent and vibrant plumage. Their feathers come in a dazzling array of colors that serve different purposes. While the color of hummingbird feathers may appear to change depending on the angle they are viewed from, their underlying structure is responsible for producing these spectacular effects.
What Makes Hummingbird Feathers So Colorful?
Hummingbird feathers get their colors from pigments as well as the microscopic structure of the feathers themselves. Pigments produce colors through selective absorption and reflection of specific wavelengths of light. Structural colors arise from the physical structure of the feather reflecting light. Together, these mechanisms allow hummingbirds to display a wide spectrum of colors.
Melanin is the most common pigment in hummingbird feathers and is responsible for browns, blacks, and grays. Carotenoid pigments produce vibrant reds, oranges, and yellows. Hummingbirds get carotenoids from their diet of nectar and small insects.
While pigments contribute to overall feather color, structural colors allow for iridescence. Iridescence occurs when microscopic structures within the feather, like melanosomes, reflect light at specific angles. As the viewing angle changes, the wavelength of light reflected changes, and different colors are observed.
The shape, density, and distribution of melanosomes in the feather determine the type of iridescence. Hummingbirds can have melanosomes arranged in layers or organized into crystal-like structures. Combinations of organized melanosomes produce brilliant iridescent colors.
Common Colors and Their Functions
While hummingbird plumage dazzles the eye, each color serves a specific purpose.
Reds, Oranges, and Pinks
Male hummingbirds often have bright red, orange, or pink plumage. These vibrant colors signal dominance and fitness to other males and help attract potential mates. The gorget feathers on the throat are a prime example. Males of many hummingbird species have brightly colored gorgets used in courtship displays.
Blues and Greens
Blue and green structural colors help camouflage hummingbirds within their environments. Greens blend into foliage while blues and purples mimic the sky. Females and juveniles more commonly display plumage in these colors.
Iridescent Browns, Blacks, and Grays
While less flashy than other colors, iridescent blacks, browns, and grays serve an important purpose. These dark iridescent feathers strengthen gorgets and crests on males and help define features. The contrast makes other colors like reds and greens stand out more.
White
Many hummingbird tail feathers have white tips. These white tips flash as the birds fly, helping maintain group cohesion and coordination. This is especially important during migration. White plumage patches may also serve as signals.
Differences Based on Age, Sex, and Species
There are some general patterns in hummingbird feather color based on age, sex, and species:
- Adult males tend to be the most brightly colored within a species. They often have iridescent throats and crests used in courtship displays.
- Adult females and young birds have more camouflaged plumage – greens, blues, black, white.
- Related species overlap in plumage color, especially among females and juveniles. But adult males differ in the specific colorful patches or iridescent feathers they possess.
- Males go through a molt at around 1 year old to attain their colorful adult plumage.
- Some species also show geographic variation in color across their range.
However, even within these patterns there is incredible diversity in color across the over 300 different hummingbird species. The table below provides some examples of common hummingbird species and the colors present on their plumage:
Species | Location | Colors |
---|---|---|
Ruby-throated Hummingbird | Eastern North America | Males have an iridescent ruby red gorget, females are green and white |
Anna’s Hummingbird | Western North America | Males have iridescent magenta head and throat, females have gray heads and green backs |
Rufous Hummingbird | Pacific Northwest | Males are brightly orange, females are green with rufous speckles |
Allen’s Hummingbird | California Coast | Males have rufous oranges and purples, females are green and white |
Costa’s Hummingbird | Southwestern deserts | Males have vivid purple crowns, females are pale below with green backs |
Violet-tailed Sylph | Andes Mountains | Males have green heads and blue tails, females are white below with green above |
Why Do Hummingbird Colors Differ?
Researchers think hummingbird feather color diversity arises from a combination of factors:
- Sexual selection – Preferences in mates drives elaboration of color in males.
- Species recognition – Unique colors help birds identify potential mates within a species.
- Elevational segregation – Separate habitats select for different colors.
- Camouflage – Certain colors are better matched to local environments.
- Behavioral strategies – Some colors tie to specific feeding or display behaviors.
Additionally, the refractory quality of feathers influences color production. Small changes in the structure of melanosomes and keratin can tune colors. As hummingbirds evolved and adapted to new environments, feather structure likely shifted in response.
Research has shown some colors correlate to specific habitats – for example, more structured iridescent feathers in cloud forests versus pigment-based colors in wetlowland areas. So color diversity arises in part from anatomy tuning to local conditions.
How Do Feather Colors Change Over Time?
While hummingbird colors are remarkably vibrant, they can fade over the bird’s lifetime due to factors like UV radiation exposure, abrasion, and pigment degradation. However, birds undergo an annual molt where old worn feathers are replaced with fresh ones.
Molting occurs in a predictable sequence over several months. Hummingbirds drop their innermost flight feathers first and move outward through the wing feathers. Tail feathers are replaced next, followed by body feathers. The energy demands of molting often cause hummingbirds to maximize food intake during this time.
Young fledglings have relatively drab feathers compared to adults. But after the first year, males molt into their brightly-colored adult plumage. Females and juveniles go through similar molt cycles, acquiring fresh camouflaged feathers.
For North American hummingbirds, the molt starts in late summer and runs through fall migration. This ensures birds have strong new feathers for their long journeys. The sequence allows key flight feathers to be replaced while still retaining flight capacity.
With each molt, vibrant iridescent colors return. Adult males may get brighter and more colorful as they age and perfect their courtship displays. Over a hummingbird’s lifetime, the molting process allows them to repeatedly renew their dazzling feathers.
How Are Hummingbird Feather Colors Produced?
In summary, hummingbird feathers get their spectacular colors from two key mechanisms:
Pigments
- Melanin pigments create blacks, browns, grays
- Carotenoids from diet give reds, oranges, yellows
- Combinations of pigments produce additional colors
Structural Colors
- Microscopic structures reflect specific wavelengths
- Melanosomes organized in layers or crystals
- Varying air bubble size in keratin structures
- Combined structural effects make iridescent colors
While pigments color the feathers directly, structural mechanisms enhance and modify these colors to create spectacular visual effects. The precision nanostructures of melanosomes and keratin make the colors of hummingbird feathers truly unique in the natural world.
Conclusion
With their specialized feathers, hummingbirds dazzle with dreamlike colors. Iridescent reds, greens, violets shimmer and change in the light. The microscopic architecture of melanosomes and keratin produce these optical wonders. Combined with pigments, structural coloration allows hummingbirds to signal mates, camouflage, and communicate. Next time you see a hummingbird, take a moment to appreciate the specialized structures behind its ephemeral beauty.