Sick Or Very Young Female Cardinal

I think I have a sick female Cardinal visiting.  She would let me get within inches or her.  I thought about catching her and taking her to a wildlife rehab, but since it was late in the evening, I just left her alone.  She was eating and drinking, but that seemed to exhaust her.  She is able to fly short distances, and I could detect no problems with her wings or legs.  If she’s still around tomorrow, I’ll see what I can do to help her.