Wow, stunning, Matthew!
And yes, that cardinal is definitely molting--I've got some ugly, ugly birds in MY backyard right now. Cardinals, blue jays, even a mockingbird, that are molting and it is just NOT pretty. But soon enough their winter plumage will come in and they will be back to their beautiful selves!
Beautiful and detailed. I love how non-intrusive the background is. Being a noob to wildlife photography and newish to photography in general, are you using a fairly fast telephoto lens and flash to pull the birds from the background? I think I see what is a flash pinpoint in their eyes and shadow on the third. Not sure if you want to divulge your secrets but I thought it wouldn't hurt to ask. Thanks. ps - greeting from Greenville, SC.