Cardinals vs. windows

We live in woodsy setting in Eastexas. about 7 days ago a female cardinal started attacking the 4 windows on one side of our house (near a bird feeder) about three days ago her spouse joined her. During daylight they hit the windows about every minute or two minutes. I am afraid they will injure themselves they are starting to look ragged.
   
Any suggestions???
   

The birds probably see their own reflections and think they are defending their territory against some intruders. Chances are they have a nest and perhaps young ones near by. Perhaps there is some way to lessen the chance of them seeing seeing their own images. If you have shades or curtains you might try closing them to see if that stops the attacks. Hope this helps.