Both parents will feed the young ones (nestlings}. The young ones will leave the nest after about 18-25 days after hatching. The parents will continue to feed them for about three weeks, until they are old enough to eat on their own.
First photo and second photos is dad feeding young ones. Third and fourth photos are of mom feeding young one.
Fifth photo is a young male downy, sixth photo is a young female downy.
During the cardinals nesting season, the male may bring his mate materials for her to build a nest. She will lay 2 or up to 5 eggs. It is the female that sits (keeps them warm} on the eggs; it may take about 12 to 14 days for the eggs to hatch. The female will sing a song to let the male know that she is ready to eat. The male will bring her food while she is nesting.
After the eggs hatch, both parents will feed the young ones. When the young ones leave the nest, the parents will feed them for a while, until they are old enough to eat on their own.
In the southern States the cardinals may raise two or three broods per season. In the middle States they will probably raise only one brood per season..
During the breeding season the male will at times bring food to the female; it is his way of winning her over. It also shows the female that he will be a good provider for when they have young ones to feed.
Most of the time the pair will stay together until one dies. The survivor will then search for another mate.
In the top photos the male is giving the female a grape. In the bottom set of photos the male is giving her a dry roasted unsalted peanut.
There aren’t many North America female birds that sing, the Northern Cardinal female in one of the females that can sing.. She will often sing at times when sitting on her nest, to let the male know when to bring food to her.
The female may at times sing a longer more complex song then the male cardinal.