Cool pictures. Now that the weather is nice, the cardinal hardly come to my feeder any more. When they did during the winter, I notice that the male often give the female the boot at the feeder. Not exactly nice, but I guess it's the cardinal way.

Neat action shots. The Cardinals around here are getting pretty feisty too.

paulsiu,,

I think you may be slightly miss-understanding a common bird habit.

Generally when birds are feeding on the ground or at a low feeder one bird will remain perched on a higher limb to watch for predators. Occasionally there will only be two birds, such as when you see the male & female cardinal. In that case one will stay up high while the other eats. then they switch places, thus if may look like the male is chasing her off.

The males were probably establishing dominance.
Male Cardinals fight to establish territories in early spring and defend them fiercely from rival males, and the females also defend their nesting grounds from other females. After a male Northern Cardinal has established a territory he whistles from the tops of trees warn to other males that the spot has been claimed.