Northern cardinal

Name and taxonomy

Carl Linnaeus described the bird in 1758, in the tenth edition of Systema Naturae. He put it in Loxia, a genus that now holds only the crossbills. It moved to Cardinalis virginianus in 1838 and passed through the name Richmondena cardinalis in 1918. The present name, Cardinalis cardinalis, was settled in 1983.

The English name honours the Roman Catholic cardinals, whose robes and caps are the same red. The word northern was added to separate this bird from the other cardinals of the Americas. It is the most northerly of them, which is what the word records. Many people still call it the redbird or simply the cardinal. Wikipedia lists 19 subspecies and Animal Diversity Web lists 18, most of them told apart by the female's face.

Evolution and relatives

The cardinal belongs to Cardinalidae, a family of 14 genera and 53 species. Every member of it lives in the Americas, between Canada in the north and Uruguay in the south. Its members run 11 to 28 centimetres long, and the males are red, yellow or blue while the females are duller. The indigo bunting, the scarlet tanager and the rose-breasted grosbeak are all relatives.

The genus Cardinalis holds only three species. The other two are the pyrrhuloxia of the south-western deserts and the vermilion cardinal, a bird of Venezuela and Colombia. The vermilion cardinal split away earliest, and this bird is the youngest of the three lineages. All three carry the crest and the thick conical bill. Like other seed-crushing cardinalids, this bird probably owes that heavy bill to a diet of hard seed.

Appearance

An adult measures 21 to 23.5 centimetres long and spans 25 to 31 cm across the wings. Weight ranges from 33.6 to 65 grams and averages 44.8 g, and males run slightly larger. The male is brilliant crimson, with a black mask that covers the eyes and reaches the upper chest. The red darkens on the back and the wings. The female is grey-brown with a red wash on the crest, wings and tail, and her mask is grey and vague.

Young birds of both sexes look like the female until they moult in the autumn. A juvenile has a grey-black bill and gains the orange-red one only with adult feathers. The red comes from carotenoid pigments in the food, not from the bird itself. A male fed only yellow pigments turns a pale red instead of crimson. A few rare birds cannot convert those pigments at all, and they grow yellow feathers and a yellow bill.

Habitat and range

Cardinals live across the eastern United States from Maine to Minnesota and south to Texas. In Canada they hold southern Ontario, Quebec, New Brunswick and Nova Scotia, east to Cape Breton Island. Southward the range crosses Mexico as far as the Isthmus of Tehuantepec, then reaches northern Guatemala and Belize. A separate population sits on the Pacific slope of Mexico between Jalisco and Oaxaca. People introduced the bird to Bermuda in 1700 and to every main Hawaiian island from 1929.

The species likes edges: woodland margins, hedgerows, brushy fields and thick cover near houses. It avoids the interior of large forests. Gardens with dense shrubs beside open lawn suit it as well as any wild habitat. The range has grown steadily since the early 1800s, and mild winters and bird feeders both helped. New England held few cardinals in 1929, and Massachusetts counts have climbed since 1960.

Diet and feeding

About 90% of the adult diet is weed seed, grain and fruit. The bird hops on the ground and through low branches to find it. Corn, oats and sunflower seeds are all taken, and the heavy bill husks them easily. Cardinals prefer seed that shells cleanly, and they grow less fussy in winter. They also drink maple sap from the holes that sapsuckers drill.

Insects and snails fill out the rest of the year's food. Beetles, cicadas and grasshoppers are the usual catch. The nestlings eat almost nothing but insects, which the parents crush before feeding them. Cardinals also eat crop pests, among them boll weevils, cutworms and caterpillars. Sunflower and safflower seed will bring the bird to a garden feeder in any month.

Behaviour and social life

The northern cardinal stays on its ground all year and never migrates. It is busiest in the early morning and again towards dusk. Pairs hold a territory through the breeding season and often travel together outside it. In winter most cardinals join flocks and roost together in cover. One study in northern Kentucky put a winter home range at about 0.212 square kilometres.

A territorial male sings from the top of a tree and chases rivals out. He will attack his own reflection in a window or a wing mirror for hours on end. Winter cold is met by fluffing the down at the base of each flight feather. The legs and feet carry no feathers and lose heat fast, so the bird shivers to make more. A cardinal can also drop its body temperature by 3 to 6 degrees Fahrenheit to survive a hard night.

Communication and senses

Both sexes sing clear whistled phrases, repeated several times and then changed. Birdwatchers write the phrases as what-cheer, what-cheer or purdy, purdy, purdy. In general a female North American songbird does not sing, and the cardinal is a well-known exception. The songs of the two sexes differ in ways the human ear cannot catch. Hormone levels are the suggested reason for that difference.

A short metallic chip is the alarm, and a parent gives it when a predator nears the nest. The same chip works as a contact call between a pair. Cardinals learn their songs, so the phrases vary from region to region. Neighbouring birds share more syllables with each other than with birds further away. Flicking the tail and raising or lowering the crest carry visual signals as well.

Reproduction and life cycle

Pairs form in early spring and may stay together for several seasons. Some pairs separate between years, and a lost mate is replaced quickly. The male courts by collecting food and passing it to the female bill to bill. Faithfulness is partial, and DNA work found 9 to 35% of nestlings fathered by another male. Mated birds sometimes sing together before they nest.

The female builds a cup nest 1 to 3 metres up in a dense shrub or a low tree. She crushes twigs in her bill until they bend, then shapes them around her body with her feet. The finished cup runs 5.1 to 7.6 centimetres tall and about 10.1 cm across, and it takes three to nine days. A pair almost never uses the same nest twice. Brown-headed cowbirds often lay in the second nest of the season.

A clutch holds three or four eggs, and counts from one to five occur. The eggs are white with a green, blue or brown tint and dark blotches, and measure about 26 by 19 millimetres. The female incubates for 12 or 13 days while the male brings her food. Chicks hatch naked and blind at about 3 to 3.5 grams and gain 2 to 3 g a day. They leave the nest 10 or 11 days after hatching, and the parents feed them for 25 to 56 days more.

Predators and threats

Adult cardinals are taken by falcons, hawks in the genus Accipiter, shrikes and several owls. Long-eared owls and eastern screech owls both hunt them. Domestic cats and dogs kill cardinals around houses. Eggs and chicks go to milk snakes, black racers, blue jays, crows, squirrels and chipmunks. A pair answers a predator with the chip call and short flights towards it, but they do not mob.

Adults survive from one year to the next at a rate of 60 to 65%. The oldest ringed wild bird lived at least 15.75 years, which is 15 years and 9 months. A captive bird reached 28.5 years. Cowbirds remove cardinal eggs from a nest and sometimes eat them. A study in Atlanta in 2016 found that cardinals suppress West Nile virus rather than spreading it.

Population and conservation

The IUCN Red List rates the northern cardinal as Least Concern. The world population stands at about 100 million birds. The global range covers roughly 5,800,000 square kilometres. Counts are stable or rising, which probably sets the bird apart from most woodland songbirds.

Numbers and range have both grown over the past 200 years. Suburbs, hedges and garden feeding created more edge habitat than the bird had before. The Migratory Bird Treaty Act of 1918 protects the species in the United States. Taking, killing or keeping a cardinal can bring a fine of up to 15,000 dollars and six months in prison. Naturalists have logged 386189 cardinal observations on iNaturalist.

Relationship with humans

Few wild birds are probably as welcome in a garden as this one. Sunflower and safflower seed bring cardinals to feeders across the whole range. That habit has pushed the range north and raised local numbers. The birds eat insect pests of crops as well as seed. No harmful effect on people has been recorded.

Cardinals were once caught and sold as cage birds for their colour and their song. The Migratory Bird Treaty Act of 1918 ended that trade in the United States. Canada protects the species under its own convention for migratory birds. American sports teams use the bird as a mascot, from the St. Louis Cardinals to the Arizona Cardinals. Most of those team images give the bird yellow legs and a yellow bill, which no real cardinal has.

In culture and myth

In Cherokee tradition the cardinal is tied to the sun and counts as a sign of good luck. In one story from that tradition the first red bird is said to be a child of the sun. Another tale is said to describe a brown bird that guides a blinded wolf and takes red rock as its reward. Some accounts are said to treat the bird as a weather prophet that sings ahead of rain. Many people today believe that a cardinal at the window may carry a message from someone who has died.

Seven states claim it: Illinois, Indiana, Kentucky, North Carolina, Ohio, Virginia and West Virginia. No other species holds that title in so many states. Delaware considered the cardinal and chose the Blue Hen instead. The Amtrak train between Chicago and Washington is named the Cardinal after the bird. The route passes through several of the states that claim it.