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Copyright Joe Dellinger 2008 |
A Yellow-Crowned Night Heron eating a crawdad in Brazos Bend State Park, Texas. Its nictitating membrane is pulled across its eye to protect it from the spines of the crawdad.
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Copyright Joe Dellinger 2008 |
A pair of Purple Martins. The male on the left has his nictitating
membrane drawn. The female on the right does not.