The Cardinal is found just about everywhere within its range, but is most commonly seen around the edges of woods and in brushy open fields. The species is very common in the suburban areas of the eastern United States. The usual food of Cardinals is seeds. However during the breeding season insects are added to the diet. Cardinals are very common birds at bird feeders.
Cardinals are territorial and very aggressive.
Territories are defended all year long. The typical Cardinal nest contains 3 to 4 pale green eggs with red-brown spots. The nest is a cup of mixed leaves, twigs, and plant fibers, usually concealed in a thicket of branches or twigs. Cardinals are very common around our house in suburban Maryland. For several years we had a resident male whose chief pleasure seemed to be attacking the glass door between the deck and the dining room.