Birds come in a stunning array of colors and patterns. Their plumage can be brightly colored or strikingly muted. Their eyes too exhibit an array of hues and shades. But do any birds actually have red eyes?
Quick Answer
While many birds have eyes that appear reddish or orange, very few birds actually have true red eyes. Most red or orange eyes are the result of carotenoid pigments in the eyes. However, some birds, like the red-eyed vireo, do possess true red eyes due to a high concentration of red retinal oil droplets. Overall, true red eyes are rare in the avian world.
What Causes Red Eyes in Birds?
There are a few different factors that can cause a bird’s eyes to appear red or orange:
- Carotenoid pigments – Many carotenoids produce yellow, orange, and red colors. Deposits of these pigments in the eyes can cause a reddish or orange hue.
- Red retinal oil droplets – These droplets contain high levels of astaxanthin and related pigments that filter light and produce red colors.
- Reflective effects – Some birds have eyes that reflect red wavelengths of light, causing a red eye shine effect.
- Albinism – Lack of pigment causes the blood vessels at the back of the eye to show through, creating a red color.
Of these causes, only red retinal oil droplets produce a true red eye color. Carotenoid pigments and reflective effects create orange, reddish-orange, or brownish-red eye colors. Albinism leads to red eyes due to blood vessels rather than actual red pigments in the eye.
Birds With Red Eyes
Here are some birds that can have true red eyes:
- Red-eyed Vireo – This small songbird has distinctive bright red eyes year-round. The red color comes from retinal oil droplets.
- Indian Roller – Native to Asia, this coraciiform bird has brownish-red eyes from carotenoids.
- Boat-billed Heron – Found in Central and South America, this heron has striking red eyes.
- Eurasian Eagle Owl – One of the largest owl species, it has orange-red eyes from carotenoids.
- Red Lory – An Australasian parrot with distinctive red plumage and orange-red eyes.
While these birds can have red eyes, many other bird species may appear to have red eyes. This reddish color is often simply due to carotenoid pigmentation or reflective effects rather than true red coloration.
Why Red Eyes Are Rare in Birds
There are a few key reasons why true red eyes are uncommon among birds:
- Carotenoid limitations – Birds cannot synthesize carotenoids and must obtain these pigments from their diet. Access limits carotenoid-based red eye coloration.
- Light filtering – Many birds filter light through yellow oil droplets. This filters out red and blue light, making red eyes rare.
- Reflectivity – Some birds have reflective tapestums that can produce eye shine. This is often yellow, white, or pale blue rather than red.
- Camouflage – Bright red eyes may make some bird species more conspicuous to predators.
Additionally, there are only a few pigments that produce true red colors in vertebrate eyes. These include astaxanthin and related carotenoid derivatives. These pigments are relatively uncommon in avian eyes compared to other animals like fish.
Differences Between Male and Female Birds
In most bird species, there is little difference in eye color between males and females. Both sexes have the same eye color and patterning. However, there are a few exceptions:
- In some species like ducks, mallards and mandarin ducks for example, the males can have more brightly colored eyes than females.
- Male birds may sometimes have eyes that reflect UV light, while female eyes do not reflect UV.
- In some species, the area around the eye differs in color between the sexes, even if eye color itself does not differ.
Overall though, eye color is not usually a reliable indicator of sex in birds. Instead, other characteristics like plumage color, size, feather patterning, and behaviors are better cues.
Differences Between Juvenile and Adult Birds
Juvenile birds can differ in eye color and pattern compared to adult birds. Some key differences include:
- Young birds may start with darker grey, brown, or black eyes that lighten with age.
- Juvenile birds may lack bright spot patterns that adults develop around the pupil.
- Eye color may attain full brilliance and iridescence as the bird reaches maturity.
However, in some species like blue jays and crows, the eyes are the same color from a very young age. But in many songbirds, eye color changes as the bird molts and replaces feathers and other structural coloration.
Do Bird Eyes Change Color?
For most bird species, eye color remains the same throughout the bird’s life once they reach maturity. However, there are some exceptions where eye color may change:
- Albino birds may start with bright red eyes that darken over time as melanin increases.
- Some birds may develop brighter eye colors during the breeding season.
- Eye color can fade or seem less vibrant as a bird ages.
- Illness, injury, or eye diseases may alter apparent eye color.
So while small changes are possible, birds do not usually undergo dramatic or seasonal shifts in eye coloration. Subtle brightness and hue changes can occur due to health, hormones, and aging though.
What Eyes Reveal About Bird Health
Examining a bird’s eyes can provide insight into their health. Here is what different eye features may indicate:
Eye Feature | What It May Indicate |
---|---|
Clear, bright eyes | Good bird health |
Pale, watery, or cloudy eyes | Sickness or malnutrition |
Crusty eyes | Infection or eye disease |
Uneven pupil sizes | Head trauma or neurological issue |
Bulging eyes | Potential internal infection |
Red, swollen, or watery eyes are common signs of conjunctivitis. Misshapen pupils can signal trauma or exposure to toxins. Any changes in eye color or clarity in a short period likely indicate an underlying health issue.
Conclusion
While many birds may appear to have red or reddish eyes, true bright red eyes are rare in the avian world. A few specialized pigments and oil droplets can produce red eye coloration, but most red-eyed birds simply have carotenoid deposits or reflective tissues that filter light. Eye color is not strongly linked to sex or age in many species, though some subtle shifts can occur between juveniles and adults. Bird eyes also provide insight into health, so observing eye appearance and activity can reveal underlying issues requiring treatment.