Friday, December 25, 2020

Hooded Merganser

Just like Great Blue Herons, I find walking by unphotographed Hooded Merganser to be very difficult. This pair of mergansers were at the Nisqually wildlife refuge on 14 December 2020. Hooded Mergansers breed in eastern North America and also in the Pacific Northwest. They enjoy a diverse diet of aquatic critters. It turns out that these ducks can change the refractive properties of their eyes. People can only affect the curvature of their lens. Many diving ducks can also change the curvature of their corneas—and they have an “extra eyelid” (the nictitating membrane) that they use much like underwater goggles. The result of these adaptations is that Hooded Mergansers have great under-water vision.

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