Fred and ______

For the last several years, we have had a pair of Cardinals here at the Boggy Thicket.  We have watched them raise several batches of babies, and have enjoyed watching their interaction.
We named them Fred and Ethel.
This year we are wondering if Fred has become a bigamist.
Ethel is still around, although she has put on some weight, and Fred is still attentive and protective as ever.  
This year though, there is another female. 
Her coloring looks just like Ethel except her beak is black with no trace of red.  The two females get along fine, and Fred spends at least as much time with the newcomer.
We've decided to name her Wilma.