|MadSci Network: Zoology|
From first-hand experience I can tell you that cardinals are very aggressive birds. On one occasion I saw one attacking his reflection in a car's hubcap and outside rear-view mirror. When extracting cardinals from mist nets they again exhibit very aggressive behavior. They always attempt to bite your fingers and hands whenever they are near enough to do so. On one occassion a cardinal caught a sharp-shinned hawk that had been attempting to get an easy meal out of the nets. Apparently the hawk missed his target and the cardinal caught the hawk's toe in his bill and would not let go. When we came upon the scene the hawk was flapping with all of his might but wasn't going anywhere. The cardinal was firmly clamped down on the hawk's toe and we had to force him to release the bird. This behavior of attacking reflections as if they were another individual is what researchers in neuroscience and cognition would label a lack of self-awareness. At present, humans and only a few other animals (dolphins and chimpanzees, I think) seem to be aware that the image in a mirror is a reflection of themselves. Most animals see this image as another individual and behave accordingly. In the case of the male cardinal the appropriate behavior would be to attempt to drive the intruder away. These patterns of behavior are interpreted by scientists studying consciousness and associated phenomena as evidence of different levels of cognitive complexity.
Try the links in the MadSci Library for more information on Zoology.