Wednesday, June 2, 2010

Brewer's Blackbird

There were several Brewer's Blackbirds in the parking lot at Fernhill Wetland as I was returning to my car after walking the main loop. This particular Blackbird caught my eye because of its "club foot". It had no trouble getting around, but walked with its toes curled under on its right foot. When trying to select which picture I was going to post I happened to notice something peculiar about its eye. There seemed to be a line through the middle of the eye and the portion of the eye to the left of this line was slightly darker. At first I wrote it off to a trick of light, but I couldn't justify what would cause it. My curiosity peeked, I looked up Brewer's Blackbird's at Cornell's very useful All About Birds site, but there was no mention of anything unusual about its eye. So then I did a generic web search of "bird's eyelid" using Google. This turned up some interesting information. Apparently, many birds, reptiles and some mammals have a third eyelid, called a nictitating membrane. This is used to help clean and apply moisture to the eye while allowing the bird to still see since it is mostly transparent. It is a single eyelid that moves horizontally across the eye. I believe what is caught in this picture is this bird's third eyelid in action having moved half way across its eye. If you would like to read more about this subject check out this link:

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