Northern mockingbird

Name and taxonomy

Carl Linnaeus described the bird in 1758 and placed it among the thrushes as Turdus polyglottos. The genus name Mimus is Latin for a mimic. The epithet polyglottos comes from Greek words for many and tongue. Both names point at the bird's talent for copying sound. Its closest living relative is the tropical mockingbird. The two form a superspecies and cross where their ranges meet in southeast Mexico.

Ornithologists recognise three subspecies. The eastern form ranges from Nova Scotia west to Nebraska and south to Texas and Florida. The western form is larger, paler and buffer, and it reaches the Pacific coast. A third form lives from the Bahamas through the Greater Antilles to the Cayman and Virgin Islands. That island form is smaller and greyer than the mainland birds.

Evolution and relatives

The mockingbird belongs to the family Mimidae, the mimic thrushes. Thrashers, catbirds and the other mockingbirds sit in the same family. Like other mimids, it has a long tail, long legs and short rounded wings. Linnaeus first placed the species with the true thrushes, and later work moved it out. Its repertoire is large, but the brown thrasher of the same family learns far more songs.

Genetic work suggests an inherited readiness to learn certain kinds of sound. A 2013 study proposed an enlarged auditory template as the basis of the skill. Sexual selection probably drives the size of the repertoire.

Appearance

The northern mockingbird is a slim grey bird with long legs and a long tail. The back is grey brown and the belly is white or greyish white. Two pale bars cross each wing. A large white patch sits on each wing and shows best when the bird opens it. The central tail feathers are black and the outer ones are white. The bill is black, long and slightly curved.

The eye is usually pale green-yellow or yellow, and a few birds have orange eyes. Young birds have streaked backs and spotted chests, and grey or grey-green eyes. Males weigh about 51 grams and females about 47 g. Males measure 22 to 25.5 centimetres and females 20.8 to 23.5 cm. The sexes are otherwise hard to separate in the field. The female has slightly darker tail feathers.

Habitat and range

The mockingbird likes open ground with scattered bushes and a high perch nearby. In the east it lives in gardens, parks, farmland and roadsides. In the west it uses desert scrub and chaparral. It feeds on short grass and needs shrubs close by for shade and for nesting. It does not nest inside dense forest.

The breeding range runs from Atlantic Canada west to southern Oregon and south through Mexico. Most birds stay in one place all year. Birds in the far north move south for the winter, though the movement is poorly understood. The species spread north through the 19th and 20th centuries. By the 1970s it lived in most counties of California. People released it on Hawaii in the 1920s, and on Barbados, Bermuda and Saint Helena.

A few birds have reached southeastern Alaska. Three have crossed the Atlantic to Britain, the last one in 2021. GBIF holds occurrence records from 34 countries. iNaturalist carries 241,164 observations of the species.

Diet and feeding

The northern mockingbird eats both animals and plants. In spring and summer it takes beetles, ants, wasps, grasshoppers, spiders and caterpillars. It also eats earthworms, small lizards and the occasional small crustacean. In autumn and winter the diet swings almost wholly to fruit. Holly, mulberry, blackberry, raspberry, dogwood, grape and fig all appear on the menu. Garden fruit such as tomatoes and apples goes the same way.

The bird hunts on the ground, in bushes, and by dropping from a perch. While it walks it opens the wings in a two-step motion that shows the white patches. Ornithologists disagree about the purpose of this wing-flashing. It may startle insects, or it may warn a predator away. The bird drinks from puddles, lake edges and rain drops on leaves. Adults have been seen drinking sap from fresh cuts on pruned trees. The taste for winter fruit probably helped the species spread north.

Behaviour and social life

The mockingbird is active by day, and it also sings at night. It lives alone or in a pair and holds a territory all year. A male sets up his territory before the breeding season begins. Two males settle a boundary with a dance, hopping side to side on the ground. One bird finally flies off, and sometimes the pair fights first.

The species defends its nest with great energy. It drives off cats, dogs, crows and hawks much larger than itself. Neighbouring mockingbirds answer a call for help and join the attack. Other birds gather to watch the intruder being chased away. A postal worker in Tulsa was struck so often that residents received a warning letter.

Mockingbirds do well in towns, and more now live in urban areas than outside them. Urban birds survive better than rural ones, probably because food is closer to hand. They return to a nest site that worked last year and avoid one that failed. Street lighting lets them feed their young after dark. City life brings costs, and birds in Baltimore and Washington suffer lead poisoning.

Communication and senses

Song sits at the centre of the mockingbird's life. One bird can hold 43 to 203 song types, and the number varies by region. Texas birds held 14 to 150 types in one study. Two Florida studies put the figure near 134 and 200. The bird adds new songs throughout its life. It copies wrens, cardinals, titmice, towhees, flickers, jays and robins, among many others.

It also copies cats, dogs, frogs, crickets, squeaky wheels and car alarms. The copies convince people more often than they convince other birds. Males start singing in late January or February and carry on into the autumn. An unmated male sings more, and from higher perches, so the sound travels further. Females sing more quietly, and mainly when the male is away. Four calls are known: the nest relief call, the hew call, the chat and the begging call.

Mockingbirds recognise individual people. In a 2009 study the birds picked out the one person who had touched their nest. A 2023 study found that they fled further from people who had behaved as a greater threat.

Reproduction and life cycle

Both sexes can breed at one year old. The season runs through spring and early summer. A male courts a female by chasing her, showing her nest sites and singing. He also flies up a few metres and parachutes down with the wing patches spread. Pairs are usually monogamous and can stay together for years. Polygyny and bigamy happen, but only rarely.

Both birds build the nest, and the male does most of the work. The female perches nearby and watches for predators. The nest sits in a shrub or a small tree, a few metres above the ground. Twigs form the outside, and grass, leaves, moss and even artificial fibres line the cup. The female lays three to five pale blue or greenish eggs blotched with brown. She incubates them alone for 11 to 14 days.

Both parents feed the chicks, which hatch blind and helpless. The young leave the nest after 10 to 12 days and become independent about two weeks later. The female often starts a second nest while the male teaches the fledglings to fly. A pair raises two to four broods in a season. Cowbirds lay eggs in mockingbird nests, and the hosts reject them more often late in the season. Wild birds live up to 8 years, and captive birds up to 20.

Predators and threats

Great horned owls, screech owls and sharp-shinned hawks kill adult mockingbirds. Scrub jays also take them, though the bird's aggression makes it a hard target. A snake rarely catches a female on the nest. Cats, crows and red-tailed hawks kill fledglings. Eggs and nestlings go to jays, crows, snakes and squirrels.

Blowfly larvae infest nestlings in Florida, and a blood parasite is common in Arizona. Winter storms limit how far north the species can live. Storms cut the numbers in Ohio, Michigan and Minnesota, and probably in Quebec. Dry seasons reduce numbers in Arizona. Lead in city soil poisons some urban birds.

Population and conservation

The IUCN lists the northern mockingbird as Least Concern. About 45 million birds live across the range. The population is large and widespread, and the range still creeps north. The United States protects the species under the Migratory Bird Treaty Act. Introduced berry-bearing shrubs have probably helped the northward spread.

The picture was very different in the 19th century. Trappers took huge numbers for the cage-bird trade, and the population fell sharply. The trade ended, and the birds recovered. Lawns, gardens and planted shrubs now suit the species well. It is one of the easiest songbirds to find in an American suburb.

Relationship with humans

The mockingbird lives close to people and is easy to watch. Gardeners value it because it eats beetles, ants, wasps and grasshoppers. It also eats soft fruit, which makes it unpopular with some growers. Its night-time singing keeps some people awake. Nesting birds dive at anyone who walks too near.

Americans once kept mockingbirds in cages for their song. Thomas Jefferson owned several, and he called one of them Dick. The trade nearly emptied some regions before it stopped. The bird is now the state bird of Arkansas, Florida, Mississippi, Tennessee and Texas. South Carolina once held it as a state bird as well.

In culture and myth

Harper Lee used the bird for the title and the central image of her 1960 novel. Her characters say that killing a mockingbird is a sin, because the bird only makes music. The lullaby Hush Little Baby promises a child a mockingbird. The song Listen to the Mocking Bird was a hit of the mid-19th century. Patti Page recorded Mockin' Bird Hill in 1951, and it reached number 2 on the pop chart. The Hunger Games books invented the mockingjay, a cross with an engineered bird.

In Hopi and Pueblo tradition the mockingbird taught the first people how to speak. In Shasta tradition the bird guards the dead. In Cherokee tradition the bird stands for a quick mind. Cherokee parents once fed mockingbird heads to children to sharpen their wits. In Maricopa tradition a dream of a mockingbird marks a person with healing power. In O'odham tradition the bird settles disputes between others.