Northern cardinal

The adult male is a brilliant crimson red color with a black face mask over the eyes, extending to the upper chest. The color becomes duller and darker on the back and wings.[11] The female is fawn-colored, with mostly grayish-brown tones and a slight reddish tint on the wings, crest, and tail feathers.[12] The face mask of the female is gray to black and is less defined than that of the male. Both sexes possess prominent raised crests and bright coral-colored beaks. The beak is cone-shaped and strong.[11] Young birds, both male and female, show coloring similar to the adult female until the fall, when they molt and grow adult feathers.[13] They are brown above and red-brown below, with brick-colored crest, forehead, wings, and tail.[5] The legs and feet are a dark pink-brown. The iris of the eye is brown.[5]

The plumage color of the males is produced from carotenoid pigments in the diet.[14] Coloration is produced from both red pigments and yellow carotenoid pigments.[15][16] Northern cardinal males metabolize carotenoid pigments to create plumage pigmentation of a color different from the ingested pigment. When fed only yellow pigments, males become a pale red color.[15] A few rare "yellow morph" cardinals lack the enzyme to convert carotenoids into red pigments, and have a yellow beak and feathers (except for black face mask). [17][18][19][20]

During winter, cardinals will fluff up their down feathers in order to retain warm air next to their body. The down feathers are small and hairlike at the base of each flight feather. The legs and feet of are thin and lack feathers, and are vulnerable to rapid heat loss.[21] In cold temperatures, cardinals will shiver and tense their muscles, especially breast muscles, to generate heat. Cardinals have the ability to drop their body temperature 3 to 6° if needed in order to survive cold temperatures.[22]

Both sexes sing clear, whistled song patterns, which are repeated several times, then varied. Some common phrases are described as "cheeeer-a-dote, cheeer-a-dote-dote-dote", "purdy, purdy, purdy...whoit, whoit, whoit, whoit", "what-cheer, what-cheer... wheet, wheet, wheet, wheet"[23] and "cheer, cheer, cheer, what, what, what, what".[13]

The northern cardinal has a distinctive alarm call, a short metallic chip sound. This call often is given when predators approach the nest, in order to give warning to the female and nestlings.[5]

The songs of the two sexes of the northern cardinal, although not distinguishable by the human ear, are sexually dimorphic. It is suggested that this is because of the differences in levels of hormones of the two sexes.[24]

The diet of the adult northern cardinal consists mainly (up to 90%) of weed seeds, grains, and fruits. It is a ground feeder and finds food while hopping on the ground through trees or shrubbery. It will also consume snails and insects, including beetles, cicadas, and grasshoppers, and the young are fed almost entirely on insects.[10] Other common items include corn, oats, sunflower seeds, the blossoms and bark of elm trees, and drinks of maple sap from holes made by sapsuckers.[25]

The northern cardinal is a territorial song bird.

The male sings in a loud, clear whistle from the top of a tree or another high location to defend his territory. He will chase off other males entering his territory. He may mistake his image on various reflective surfaces as an invading male and will fight his reflection relentlessly. The northern cardinal learns its songs, and as a result the songs vary regionally. Mated pairs often travel together.[26] The songs of a northern cardinal will usually overlap more in syllables when compared to other northern cardinals near it than those far away from it.[27]

Pairs may mate for successive years, but some also "divorce" between seasons or choose a new mate when one dies.[28] Pairs generally stay together year-round but are not necessarily monogamous. DNA studies of two populations of cardinals found that 9–35% of nestlings were not fathered by the female's mate.[28] Mated pairs sometimes sing together before nesting. During courtship they may also participate in a bonding behavior where the male collects food and brings it to the female, feeding her beak-to-beak.[23]

Males sometimes bring nest material to the female, who does most of the building. She crushes twigs with her beak until they are pliable, then turns in the nest to bend the twigs around her body and push them into a cup shape with her feet. The cup has four layers: coarse twigs (and sometimes bits of trash) covered in a leafy mat, then lined with grapevine bark and finally grasses, stems, rootlets, and pine needles. The nest typically takes three to nine days to build; the finished product is 5.1–7.6 cm (2.0–3.0 in) tall, 10.1 cm (4.0 in) across, with an inner diameter of about 7.6 cm (3.0 in). Cardinals do not usually use their nests more than once. The female builds a cup nest in a well-concealed spot in dense shrub or a low tree 1–3 m (3.3–9.8 ft) off the ground. The nest is made of thin twigs, bark strips, and grasses, lined with grasses or other plant fibers.[29]

The oldest wild cardinal banded by researchers lived at least 15 years and 9 months, although 28.5 years was achieved by a captive bird.[30] Annual survival rates for adult northern cardinals have been estimated at 60–65%.[31]

• 
  Newly hatched
• 
  At one week of age
• 
  Female feeding a chick
• 
  Fledgling at a box feeder
• 
  Juvenile male northern cardinal (left) at feeder with female house finch
• 
  Male juvenile in Manhasset, New York
• 
  Female juvenile in Manhasset

There are usually 3 or 4 eggs per nest, though there are sometimes 1–5.[8] The eggs are white, with a tint of green, blue, or brown, and are marked with lavender, gray, or brown blotches which are thicker around the larger end.[32] The shell is smooth and slightly glossy.[29] Eggs measure approximately 26 mm × 19 mm (1.02 in × 0.75 in) in size.[32]

Eggs are laid one to six days following the completion of the nest. Three or four eggs are laid in each clutch. The female generally incubates the eggs. The male may incubate for brief periods of time, though this is rare. Incubation takes 12 or 13 days.[29] Young fledge 10 or 11 days after hatching. Two or three, and even four, broods are raised each year.[29] The male cares for and feeds each brood as the female incubates the next clutch of eggs.[25]

Nest with three eggs in Durham, North Carolina

Cardinals in Massachusetts have been observed to nest in thick and dense shrubs, trees, and vine tangles, making nests out of twigs, grass, and plant fibers.[8] The eggs are usually incubated by female cardinals, who have brood patches, while the male cardinal forages for food.[33]

Newly hatched cardinals weigh an average of 3–3.5 grams,[5] are naked, blind, and immobile, and do not have feathers until they are 4-5 days old.[5] Unlike adults, their diet is mainly composed of insects, which adults crush with their beaks and feed to them.[5] They gain weight at a rate of about 2–3 grams per day, but grow a bit slower until day 2, faster from day 2 to day 7 or 8, and then slower for the day or two before fledging.[5]

Nestlings vocalize to attract parents for feeding. Very young nestlings will beg if the nest is moved, but as they grow older, they start to only respond to their parents' presence or their songs.[5]

Nestlings defecate in the form of a fecal sac, where the fecal matter is enclosed by a tough mucus membrane. They are produced every 3 or 4 feedings, and female cardinals sometimes stimulate defecation by poking the nestling near the cloaca. Fecal sacs from the first 4- or 5 days of nesting are eaten by the parents, and later sacs are carried away from the nest and dropped.[5]

Northern cardinals are preyed upon by a wide variety of predators native to North America, including falcons, all Accipiter hawks, shrikes, bald eagles, golden eagles and several owls, including long-eared owls, and eastern screech owls. Predators of chicks and eggs include milk snakes, coluber constrictors, blue jays, crows, eastern gray squirrels, fox squirrels, eastern chipmunks, and domestic cats.[10]

Cowbirds have been observed to parasitize their nests.[8]

• 
  The male often feeds the female as part of their courtship behavior.
• 
  Male cardinal feeding on American beautyberry at Okeeheelee Nature Center, Florida
• 
  A male northern cardinal feeding on a bird feeder

In the United States, the northern cardinal (referred to as just "cardinal") is the mascot of numerous athletic teams; however, most teams portray the bird with a yellow beak and legs. In professional sports, it is the mascot of the St. Louis Cardinals of Major League Baseball's National League and the Arizona Cardinals of the National Football League, which for many years were also based in St. Louis. In college athletics, it is the mascot of many schools, including Ball State University, The Catholic University of America, Illinois State University, the University of the Incarnate Word, Lamar University, the University of Louisville, the Massachusetts College of Pharmacy and Health Sciences, North Idaho College, Otterbein University, Saint John Fisher College, the State University of New York at Plattsburgh, Wesleyan University, Wheeling University, and William Jewell College.[38]

The northern cardinal is the state bird of seven U.S. states, more than any other species: Illinois, Indiana, Kentucky, North Carolina, Ohio, Virginia, and West Virginia; although in each case the particular state just refers to the bird as "cardinal". It was also a candidate to become the state bird of Delaware but lost to the Delaware Blue Hen.[39]