I have 7 male Cardinals here as I type. Females are about the same. I would guess have about 20 Cardinals living around my home. I always have lots.
They eat all seeds and over the years have grown to like my peanut butter mix. They also like chopped peanuts. Thinking on it, guess they eat everything. Maybe that is why they prosper so well?

They are the first birds at my bed room window feeder and the last to show at my feeders in the evening.

In Spring they fight over mates and territory. Some nest in my Leyland Cypress, and all sleep in those or the Pyracanter.
They are beautiful, noisy, tame - just a perfect backyard bird.