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Name: Stephanie
Status: educator
Age: other
Location: OR
Country: N/A
Date: 11/17/2005
Question:
We have two educational birds at our camp. One is a Great Horned Owl and one is a Red-Tailed Hawk. The owl has beautiful orangish-yellow eyes and the Red-Tail has brown. In several bird books I have learned that most raptors eyes change color with age. Why is that? Does it have something to do with melanin? Do Owls eyes change color with age as well? Why do so many Owls have the yellow iris and then there are some with all black eyes? Is there any benefit to having yellow eyes or black eyes? Why are the Cooper Hawk's eyes red?

Replies:
From a thorough but somewhat dated (1988) reference, The Birder's Handbook, Ehrlich, Dobkin, & Whey: "Although the physiology of iris pigmentation is poorly understood, changes in color with age and with season are likely to be under hormonal control...." In this article, owls are NOT listed in the many groups known to have eye color changes. On different colors of bird's eyes see this previous response:

http://www.newton.dep.anl.gov/askasci/zoo00/zoo00586.htm

or from another Q&A

page: http://www.madsci.org/posts/archives/mar2001/984710180.Zo.r.html

J. Elliott

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