On November 21st, this interesting looking cardinal showed up at a backyard birdfeeder in Eden Prairie, MN. Thanks to Nancy for letting me re-produce the photos. She wasn't sure what was up with this strange looking female Northern Cardinal chowing down at her Yankee Whipper. The head is white but it still has a red crest. This is a pretty classic example of partial leucism. I've posted a number of images of leucistic birds from around the metro before. There was the Leucistic American Goldfinch (also with white on the head though not as much as this cardinal. I really liked this leucistic American Robin as well. One of my favorites though was this odd leucistic purple finch that looked like some sort of odd ring-necked finch.
Leucism results from defects in pigment cells in an animal's body. It can affect just one cell or all of the cells on an animal. This means we can get a bird with just one odd white feather or, as in this case, white feathers in just one part of the body. We can even get a leucistic bird with all white feathers but normal colored eyes, beak and legs. These are the individuals that are most often mistaken for albinos. A leucistic animal is sometimes called a partial albino but technically this is incorrect as albinism has a completely different cause and is systemic, never partial. True albinos lack melanin in all of the cells in their body thus the oddly colored eyes, beak and legs.