The great horned owl is one of the most common and widespread owls in North America. Known for its large facial disk, prominent ear tufts, and deep hooting calls, the great horned owl is a impressive bird of prey. One of the distinguishing features of the great horned owl is its striking eyes. But what color are the eyes of the great horned owl? Here we will take a closer look at the eye coloration of this fascinating nocturnal hunter.
Iris Color
The iris is the colored part of the eye surrounding the pupil. In great horned owls, the iris color can range from yellow to orange to reddish brown. However, the most common iris color is yellow-gold. This striking eye color helps give the great horned owl its piercing gaze.
The yellow to orange iris color develops as the owls mature. Young great horned owls hatch with dark gray to blue-gray irises. Over the first several months of life, the iris color gradually changes to the adult yellow or orange hue. By one year of age, the eye color is typically fully developed.
Interestingly, the left and right iris can differ slightly in color within the same owl. One iris may be more yellow, while the other trends a bit more orange. This minor variation is normal and does not indicate any health issues.
Factors Influencing Iris Color
Several factors may influence the exact iris color within a population of great horned owls. These include:
– **Subspecies** – There are at least 16 recognized subspecies of great horned owls across North America. Some subtle variations in plumage and eye color can occur between subspecies. For example, the paler Arctic race Bubo virginianus subarcticus tends to have lighter yellow eyes compared to more southern populations.
– **Individual variation** – Like humans, eye color varies naturally between individual owls based on genetic differences. Two owls in the same location may have slightly different iris shades. This individual variation contributes to the range of iris colors.
– **Diet** – Carotenoid pigments obtained from the diet can accumulate in the iris, influencing its color. Great horned owls with higher carotenoid levels may exhibit more vibrant, orange-toned eyes.
– **Light exposure** – The iris contains special pigment cells called melanocytes. In low light conditions, these cells expand to cover more of the iris, darkening its color. So an owl’s iris may appear darker in the brightest daylight versus at night.
– **Age** – As mentioned earlier, juvenile owls have distinctly lighter grayish irises that darken to adult yellow-orange hues by one year old. The intensity of the iris color may also change somewhat with advancing age.
Eye Color Legends and Mythology
Those striking yellow to orange eyes have inspired some legends and mythology around the great horned owl. Here are some examples:
– Native American tribes of the Pacific Northwest believed the great horned owl was a transformed hunter condemned to turn into an owl as punishment for evil deeds. The owl’s yellow eyes were seen as glowing with an inner fire as a reminder of this curse.
– Across many North American tribes, the owl’s glowing eyes earned it a reputation as a messenger of death or bringer of bad luck when seen. The bright yellow eyes were associated with the owl’s supernatural abilities to detect human misdeeds and foretell mortality.
– In Mexico, the Aztecs viewed owls as the companions of the goddess of darkness, death, and sorcery. The owl’s luminous eyes, capable of seeing at night, symbolized a portal between the world of the living and the underworld of death.
– European folk tales sometimes portrayed the owl’s eyes as burning coals or sparks stolen from the fires of Hades. The glowing eyes were thought to allow the owl to move between the realms of the living and dead under the cloak of night.
So in mythology worldwide, the great horned owl’s vivid yellow-orange eyes have been shrouded in supernatural symbolism and taken as omens, for good or evil.
Tapetum Lucidum
What really makes a great horned owl’s eyes “glow” is not fiery myth, but the tapetum lucidum. This is an organelle on the retina at the back of the eye that reflects visible light back through the retina, increasing visual sensitivity in low light.
The color of the reflected light from the tapetum lucidum depends on the amount of zinc or riboflavin present in the owl’s diet. More zinc produces a blue-green retinal glow, while more riboflavin results in yellow to orange retinal shine.
In the great horned owl, the tapetum lucidum glow is yellow-orange which matches its natural iris color. However, the retinal glow can make the owl’s eyes appear even more luminous yellow than the actual iris color, especially when a bright light unexpectedly shines into its eyes.
This nocturnal hunter relies on the tapetum lucidum for excellent night vision to locate and capture prey in low light. But the spooky side effect is a pair of giant glowing owl eyes in the beam of a flashlight at night!
Eye Color Changes
While the adult eye color remains relatively stable, there are some circumstances that can alter the typical yellow to orange iris coloration in great horned owls:
– **Eye trauma** – Injuries to the eyes, either from impact or infections, can damage the iris and cause permanent color changes. Healing trauma may leave white, cloudy splotches on the iris.
– **Disease** – Certain illnesses like avian pox can cause nodules or scarring on the iris leading to irregular pigmentation. Eye diseases may also result in overall color dulling.
– **Toxicity** – Environmental toxins and heavy metal poisoning can influence melanin pigment production, skewing the normal iris color over time.
– **Albinism** – Albino owls lack melanin throughout the body including the eyes. This results in a distinctive red or pink eye color rather than the usual yellowish hue.
– **Aging** – Advancing age may cause the iris to fade or take on a paler, more washed-out appearance though this varies individually.
So while the adult owl’s eye color is generally fixed, unusual circumstances can alter the eyes from their normal brilliant yellow or orange.
Conclusion
The eyes of the great horned owl are most commonly a striking yellow-orange color with the left and right iris sometimes differing slightly in shade. This bold iris color contributes to the owl’s intense gaze. The glowing appearance of the eyes comes from the light-reflecting tapetum lucidum on the retina, not actual fire as some myths suggest! So next time you catch sight of a great horned owl, take a moment to admire its beautiful and unique eyes. Just don’t stare too long or those shining eyes just might cast a supernatural spell over you!
References
| Source | Information |
| The Sibley Guide to Birds, 2nd Edition | Details on great horned owl iris color range and development |
| All About Birds – Great Horned Owl | Overview of key identification features including eye color |
| Journal of Avian Biology | Research study on iris color and factors influencing pigmentation |
| Wildlife Journal Junior | Article examining folklore linking owls to death and the underworld |
| Veterinary Ophthalmology journal | Case studies of diseases and trauma altering great horned owl eye color |
| Biology Letters | Study on the function of the tapetum lucidum for enhancing night vision |
