The cardinals around here are very flighty and will take off the instant I try to take a picture, especially the males. The females are slightly more tolerant of my presence, but they'll fly away if the males do. The other birds like the finches and juncos will scatter quickly if startled, but they also return pretty quickly as long as I remain still. The cardinals are hesitant to do that if I'm anywhere nearby. This makes them extremely difficult to photograph.
I had to hang around on the unheated kitchen porch with the window open for half an hour in sub-freezing temperatures and with a snow storm going on outside to get these photos. The photo of the female was particularly difficult as the falling snow was interfering with the autofocus, so I had to focus the camera manually.