Why Are Birds Different Colors?


There are thousands of species of birds here
on Earth and with those great numbers come great biodiversity. Birds are among the most colorful animals
on the planet, and scientifically speaking, it’s because different species can employ
a wide range of chemical and physical tricks to make them stand out – or disappear – depending
on what suits them. When looking at the plumage of a bird, there
are really two factors that define the “color” that you see – pigmentation and structure. Pigments are chemicals that absorb certain
wavelengths of visible light, leaving the remaining light to be reflected from a surface
to give it its color, while structural colors are produced by the way that the physical
structure of the feather interacts with visible light. Birds are also “tetrachromatic,” which
means they can see four colors: all the colors we see, plus they can also reach into the
UV spectrum too! This has lead to certain species of birds
to develop plumages that are more complex than we can even perceive! There is a variety of forms of pigmentation
in birds, but we are going to focus on three different kinds, carotenoids, melanins, and
porphyrins. Some of these pigments are produced in bird’s
bodies, while others are taken from food sources. Different species of birds use different combinations
of them to create unique looking plumages. Carotenoids are a diet-based class of pigments
that birds ingest from food and deposit into their feathers. These yellow to red pigments give foods like
carrots and corn their color. Carotenoids are broken into two subgroups,
oxygen-containing xanthophylls and oxygen-less carotenes. Flamingos for example, are gray when young,
but after eating enough carotenoid-containing brine shrimp and algae, they become pink. Other birds metabolize the ingested carotenoids
to create their color, which is how yellow canaries get their yellow and cardinals get
their red. Melanin is a pigment found in many animal
species, including ourselves! Unlike carotenoids, these pigments are produced
in the feather by special cells called melanocytes, and there are two different types. Eumelanin create blacks and grays, while pheomelanin
is often buff, brown, or chestnut in tone. What makes melanin stand out from other pigments
is that it also acts to reinforce the structure of the feather, strengthening the wings for
flight. This is why the tips of feathers and the feathers
on wings are darker. One of the less common forms of bird pigmentation
comes from compounds called porphyrins. Generally, these web-like molecules are responsible
for vibrant colors in biology – hemoglobin and chlorophyll are good examples. In birds, these usually produce different
shades of brown, as in the feathers of owls and bustards, but also can create vibrant
reds and greens, as in birds like turacos. But what really makes porphyrins stand out
to birds, is that they fluoresce in a bright red under UV light! Beyond pigments, so-called structural coloration
also can generate a diverse array of feather colors. These are produced in feather barbs and barbules
by microstructures that can absorb or scatter different wavelengths of light to produce
a range of colors and visually striking effects. First and most basic, white comes from the
un-pigmented keratin layer on the exterior of a barb. The intensity and brightness of the white
is dependent on how light is bounced around by tiny air vacuoles inside. To create structural colors like blue, in
an area just below the keratin exterior, keratin rods and air vacuoles of various shapes and
sizes assemble together and scatters or absorbs certain colors of light, bouncing off another
to produce what you see. It’s then backed by a black layer of melanin
to make sure the effect isn’t wrecked from light coming in the other direction. This type of structural color can create ultraviolet
patterns too. Angle-dependent effects of these colors are
also possible, which is the case for iridescence. The physical cause is similar to how structural
blue is made. The way light bends off of the structures
changes our perception of color based off of the angle of viewing and the incidence
of light. Also, nano-structures in some bird feathers
can take almost all light away too, producing a black that’s blacker than black! Researchers discovered recently that structures
in birds of paradise are so effective at repeatedly bouncing light, that they absorb 99.95% of
the light that hits them! These many different methods of producing
color can combine to create the amazingly colorful spread of bird feathers. We never asked, how many birdwatchers do we
have out there? Bird science is a recent discovery for us,
and we want some more topics to cover – post them down in the comments below! Thanks for watching.

17 thoughts on “Why Are Birds Different Colors?

  1. Used to be a bird owner and I really like know more about beaks in general, since birds are born with them while we humans are still developing our teeth months after birth.

  2. Here’s a question about birds: What chemical processes go underway in hatching eggs, bird flight, or morphological attributes like beak size?

  3. maybe try to get an interview with charles kelly from philadelphia in. he's and expert on birdlaw, and in fact the best goddamn bird laywer in the world, so i've heard!

  4. I dont know about birds and i'm certainly not a chemist but i'm a biologist studying sea slugs and there is approximately 18-20 episodes of material just off the top of my head. For example, sea hares and how they use their 'ink' differently from cephalopods and how chemoreception plays a role. The role of the opaline gland and the unique chemistry associated with its fluid. The fact that pleurobranchs secrete acid to defend themselves. etc etc etc. Not even going to try to expand on the world of secondary metabolites from nudibranchs etc and their role in defense, camouflage, medicine, etc

  5. Interesting but I got stuck on how the presenter decided the word carotinoid could possibly be pronounced 'coratinid'. Corat juice anyone?

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