I was interested in looking up some info on the Northern Cardinal after my neighbor has had a female Cardinal persistently tapping at her dining room window. A few years ago we had taken a picture of a mother cardinal and her babies in a nest in the cherry tree in front of that dining room window.
I found the following information at http://www.birds.cornell.edu/BOW/NORCAR/
Description: Northern Cardinals are a medium-sized songbird (approximately 8.75 inches in length) with short, rounded wings, a long tail, a heavy conical bill, and a crest. Males are nearly all brilliant red; brownish-gray-tinged scapular and back feathers give the upper parts a less colorful appearance. The coral red bill is surrounded by a mask of black that extends to a dark eye and includes the chin and throat. Legs and feet are dark red.
The female is soft grayish brown on the back with variable areas of red on the tail, crest, and wings. The underparts are a warm pinkish brown. Her coral red bill is also surrounded by darker but not black feathers, so her mask is not as distinct as the male's. Females are slightly smaller than males.
The juveniles are like females but more brown in color, with shorter crest and a blackish bill. They molt to adult plumage in fall.
Cardinals are noted for their loud, clear whistled songs, often sung from a high treetop song post. Females will counter sing, duetting with males—usually after the males have established territories and before nesting begins. Local variations and accents have been noted in cardinal songs.
Typical habitats are thickets and brushy areas, edges and clearings, riparian woodlands, parks, and residential areas. Here the nonmigratory cardinals feed on a variety of foods including seeds, leaf buds, flowers, berries, and fruit. Up to one-third of its summer diet can be insects. Its winter diet is 90 percent vegetable matter, especially large seeds. Winter flocks can be very large, up to 60 or 70 individuals in areas of abundance.
Cool fact: In the 1800s Cardinals were much-sought-after cage birds highly valued for their color and song. Thousands were trapped in the south in the winter and sent to northern markets, and thousands more were sent to Europe. This trade ceased, fortunately, with the passage of the Migratory Bird Treaty Act of 1918.
The common and familiar Northern Cardinal is a bird whose range has expanded northward in the last 100 years. Originally a bird of the Southeast, the Northern Cardinal's range expanded north and northwest along the Mississippi River and its tributaries. In 1886 this cardinal was found only occasionally north of the Ohio River. By 1895 it had reached the Great Lakes, and by 1910, it was found in southern Ontario.
"Although some birds are polygamous, most are monogamous at least for a single summer season. In a few species, birds returning to last year's territory remate with the same returning partner, and some birds will reunite for breeding year after year throughout thier lives.
Cardinals not only mate for life, they remain together the whole year, generally in unruffled tranquillity. Long before winter is over, they are both singing again, sometimes solo but more often counter singing--one bird trilling several phrases, which the other completes. As spring returns, the male resumes his courtship feeding, bringing his companion tidbits of food, their bills touching briefly as she accepts each offered morsel.
The female builds the nest alone, while the male is close beside her, exuberant in song. The female also incubates the eggs alone, but the male feeds her on the nest, and together they work to exhaustion feeding their first nestlings of each season. Then, as the female starts her second brood, they resume the counter singing and courtship feeding that so beautifully express the harmony of their life."
This info comes from the Reader's Digest Book of North American Birds.