15/04/2026
✨️Continuation of Ameraucana eye color Q &A✨️
The cause of eye color variations in our Ameraucana flock is influenced by the presence of different pigments and structures within the iris that absorb and reflect light.
A bird iris has three layers:
1) Pigment Epithelium
2) Stroma
3) Anterior Border Layer
The posterior area of the iris, which is known as the Pigment Epithelium, is rich in melanin. Melanin is a pigment that is responsible for dark eye coloration. The Pigment Epithelium is generally not associated with the visible iris eye color that we see in our Ameraucana. It is covered by pigments and stuctures in the other two layers.
The Stroma is a thick middle layer of the iris that contains muscle, connective tissue, nerves and pigment cells. Melanin deposited in the stroma portion of the iris will cause Ameraucana eye color to be brown. If the eyes on your Ameraucana are brown, it is permanent. If you are breeding to Standard, its time to let this Ameraucana go as the Standard calls for reddish bay eye color.
Yellow pigment granules from carotenoids can be contained within and around the muscle and connective tissue in the Stroma which can also impact the eye color. The carotenoids are derived from xanthophyll and carotene which is found in feed. The more carotenoids that are accessible in feed, the more yellow the eye color will be from the presence of yellow pigment granules. On the other hand, a carotenoid free diet prevents deposit of yellow pigment in the iris. Interestingly, eye color may change in egg-laying females because the demands of yolk production reduce carotenoid availability for iris coloration. In the non-laying hens pigment from the carotenoids can be seen in the intercellular globules and the striated fibers of the dilatator and sphincter muscles of the iris.
Check your feed bag to see what ingredients it contains and how they may be impacting the eye color of your Ameraucana flock! Why are carotenoids useful in feed? They provide important immunological and oxidative benefits.
The Anterior Border Layer is the other layer of the eye and contains pigments as well as blood vessels that influence eye color.
In addition to melanin and carotenoids, purine and pteridine pigments affect eye color in some species of birds. They are commonly found in light irises.
Are there other things that can affect the appearance of eye color beyond melanin, carotenoids, purine, and pteridine? Yes.
Structural features and blood vessels can impact the appearance of eye color. The blood vessels affect eye color due to their size, arrangement, and hemoglobin content. Enlarged blood vessels will make the eye color appear more red. The appearance of the eye color is further impacted by the distance of the blood vessels from the surface of the eye. Remember that increased blood flow and increased blood vessel diameter equals a more red eye color appearance.
The reddish bay eye color that our Ameraucana should have is a result of red pigment from hemoglobin and yellow pigment from carotenoids. “Bay” is defined as “an intermingling of red and yellow in the iris caused by surface capillaries in the eyes.” This definition lays the groundwork for correctly identifying “reddish bay” eye color in our flock.
Interestingly, if you zoom in on reddish bay eye color using an opthalmoscope, the red capillaries and the yellow pigments from carotenoids that create reddish bay eye color can be seen separately!
Remember that the standard was written for sexually mature birds. Pullets and cockerels that have green eye color are typically headed in the right direction to achieve reddish bay eye color.
What we can see via our discussion so far is that some pigments are considered residual and permanent (melanin) while other pigments are more variable and not considered permanent (carotenoids). The impact of hemoglobin on eye color due to blood vessel size, arrangement, and general blood flow is considered physiological.
It is worth noting that pathological conditions can lead to color changes in a diseased eye.
It is apparent that no one factor alone is responsible for all deviations in reddish bay eye color for our Ameraucana flock. Hopefully this post is helpful to you as you as you assess eye color in your Ameraucana.
*Analysis of scientifically based research on plumage color genes and the E locus alleles in regard to their potential impact on Ameraucana eye color will be completed next.
