Pairs of birds can often be seen spitting out loud, clear whistling noises year round. It is not uncommon for females to counter sing with a male, whistling a duet of sorts. Some variations in song, such as accent, have been noted in cardinals living in different regions. Cardinals survive on a diet made up mostly of insects. Because of this, cardinals are often introduced into areas in North America to help control insect populations.
Cardinals also eat seeds, wild fruit, leaf buds, berries and flowers.
Almost one-third of the cardinal's summer diet consists of insects, and 90 percent of its winter diet is made up of vegetable matter. Cardinals live in nests, which are made from small collections of twigs, pieces of bark, roots, and lined with grass. Their natural habitats include thickets, bushes, woodlands, parks, and residential areas. If you've spotted one cardinal, it's most certain that its partner is close by. The female cardinal lays 3-5 eggs at one time and incubates them herself while the father brings food to her.