I hope you dont mind me chiming in here.. lol i have a photo of an unusual color mutation for a cardinal..
she seems to be hanging around here for the suet cakes I make.. the Pied mutation in wild birds is fairly rare.. only becomming common.. like in cockatiels.. when in bred and line bred to seat that mutation a bit more in the genetic makeup .. (used to breed cockatiels)
also there is a cream color make robin . almost white that hangs around this one amish ladies house.. tho she said she has not seen him for a year so he might be gone for good..