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Bald Eagle’s Nictitating Membrane

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Last updated March 2010

Bald eagle's eyelid on and off.

Compare the bald eagle inner eyelid

This bald eagle is a three year and a half old female named Pandora. The bird belongs to Stephen Bucciarelli from Predator Bird Services. We met Pandora during the Wings of Spring Festival in Rondeau Park. We estimate that during Stephen's inspiring 1-hour long presentation, Pandora blinked her inner eyelid approximately 1000 times.

It takes about five years for the Bald Eagle to reach maturity and to gain its distinctive white head and tail that everybody recognizes. For this reason, young bald eagles are easily confused with golden eagles, especially when observed from a distance. Learn the clues provided by our readers on how to correctly identify the young bald eagle from the golden eagle.

As an interesting fact, birds are not the only species that have a nictitating membrane. Reptiles, sharks, amphibians, and some mammals such as polar bears have it too.

Let's take a closer look at Pandora and see the nictitating membrane at 100% magnification. Note the blood veins traversing the eyelid in great numbers.

Bald Eagle Inner Eyelid Closeup - Nictitating Membrane

We hope to meet Pandora and Stephen again. Till then we wish them both good 'hunting'.

Examples of the Nictitating Membrane in Other Birds

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