Cardinals may form winter flocks of 60-70 birds. Males care for the first brood while the females are incubating a second clutch in a new nest. Females usually sing after males establish territory but before nesting starts. Females dull colors help camouflage them from predators. Males bright colors help attract a mate.
Males are duller in winter.
Male cardinals vigorously defend their territory. They have been known to attack their reflections in mirrors, windows and chrome. Sometimes they will even attack small red objects they mistake for other males. Most small birds only live for a year or two. One cardinal was caught almost 16 years after it was initially banded.