The northern mockingbird (Mimus polyglottos) is a mockingbird commonly found in North America, of the family Mimidae. The species is also found in some parts of the Caribbean, as well as on the Hawaiian Islands. It is typically a permanent resident across much of its range, but northern mockingbirds may move farther south during inclement weather or prior to the onset of winter. The northern mockingbird has gray to brown upper feathers and a paler belly. Its tail and wings have white patches which are visible in flight.
The species is known for its ability to mimic bird calls and other types of sound, including artificial and electronic noises. Studies have shown its ability to identify individual humans and treat them differently based on learned threat assessments. It is an omnivore and consumes fruit, invertebrates, and small vertebrates. It is often found in open areas, open woodlands and forest edges, and is quite common in urbanized areas. The species breeds from southeastern Canada throughout the United States to the Greater Antilles. It is listed as a species of least concern by the International Union for Conservation of Nature.
The mockingbird is influential in United States culture, being the state bird of five states, appearing in book titles, songs and lullabies, and making other appearances in popular culture.
Taxonomy Swedish zoologist Carl Linnaeus first described this species in his Systema Naturae in 1758 as a species of thrush, Turdus polyglottos. Its current genus name, Mimus, is Latin for "mimic" and the specific polyglottos, is from Ancient Greek , "harmonious", from polus, "many", and glossa, "tongue", representing its outstanding ability to mimic various sounds.
The closest living relative of the northern mockingbird is the tropical mockingbird (Mimus gilvus); the two form a superspecies, and occasional hybrids have been recorded where they overlap in Oaxaca and Veracruz in southeast Mexico.
Subspecies There are three recognized subspecies for the northern mockingbird. There have been proposed races from the Bahamas and Haiti placed under the orpheus section.
M. p. polyglottos (Linnaeus, 1758): generally found in the eastern portion of North America ranging from Nova Scotia to Nebraska, to as far south as Texas and Florida. M. p. leucopterus, the western mockingbird (Vigors, 1839): generally found in the western portion of North America ranging from northwestern Nebraska and western Texas to the Pacific coast, and south to Mexico (the Isthmus of Tehuantepec), and Socorro Island. It is larger than M. p. polyglottos and has a slightly shorter tail, upperparts are more buff and paler, underparts have a stronger buff pigment. M. p. orpheus (Linnaeus, 1758) from the Bahamas to the Greater Antilles, also the Cayman and Virgin Islands. Similar to M. m. polyglottos except smaller, a paler shade of gray on its back, and underparts with practically little, if any buff at all.
Description
The northern mockingbird is a medium-sized mimid that has long legs and tail. Males and females look alike. Its upper parts are colored gray, while its underparts have a white or whitish-gray color. It has parallel wing bars on the half of the wings connected near the white patch giving it a distinctive appearance in flight. The black central rectrices and typical white lateral rectrices are also noticeable in flight. The iris is usually a light green-yellow or a yellow, but there have been instances of an orange color. The bill is black with a brownish black appearance at the base. The juvenile appearance is marked by its streaks on its back, distinguished spots and streaks on its chest, and a gray or grayish-green iris.
Northern mockingbirds measure from including a tail almost as long as its body. The wingspan can range from and body mass is from . Males tend to be slightly larger than females. Among standard measurements, the wing chord is , the tail is , the culmen is and the tarsus is .
The northern mockingbird's lifespan is observed to be up to 8 years, but captive birds can live up to 20 years.
Distribution and habitat The mockingbird's breeding range is from the Maritime provinces of southern Canada, westwards to southern Oregon, and south through practically the entire continental United States south of the northern Plains states and Pacific Northwest, the Greater Antilles, and the majority of Mexico to eastern Oaxaca and Veracruz. The mockingbird is generally a year-round resident of its range, but birds that live in the northern portion of its range often move south during the winter season. The mockingbird is thought to be at least partly migratory in the northern portions of its range, but the migratory behavior is not well understood. Small numbers of northern mockingbird have also been recorded north of the breeding range, north to southeastern Alaska, and three times as transatlantic vagrants in Britain, most recently an individual which moved northeast through Britain from Devon via West Sussex to Northumberland in February to May 2021.
In the 19th century, the range of the mockingbird expanded northward towards provinces such as Nova Scotia and Ontario and states such as Massachusetts, although the sightings were sporadic. Within the first five decades of the 20th century, regions that received an influx of mockingbirds were Maine, Vermont, Ohio, Iowa, and New York. In western states such as California, the population was restricted to the Lower Sonoran Desert regions but by the 1970s the mockingbird was residential in most counties.
Islands that have had human-mediated introductions of mockingbirds include Hawaii (where it was introduced in the 1920s), Barbados, St. Helena, Socorro Island, the Cayman Islands, Tahiti, and Bermuda (in which it failed).
The mockingbird's habitat varies by location, but it prefers open areas with sparse vegetation. In the eastern regions, suburban and urban areas such as parks and gardens are frequent residential areas. It has an affinity for mowed lawns with shrubs within proximity for shade and nesting. In western regions, desert scrub and chaparral are among its preferred habitats. When foraging for food, it prefers short grass. This bird does not nest in densely forested areas, and generally resides in the same habitats year round.
Behavior Diet
The northern mockingbird is an omnivore. The birds' diet consists of arthropods (such as spiders, grasshoppers, wasps, bees, ants, beetles, butterflies, and caterpillars), earthworms, berries, fruits, seeds, and occasionally flowers, small crustaceans, and lizards (Anolis spp.). Mockingbirds can drink from puddles, river and lake edges, or dew and rain droplets that amass onto plants. Adult mockingbirds also have been seen drinking sap from the cuts on recently pruned trees. Its diet heavily consists of animal prey during the breeding season, but takes a drastic shift to fruits during the fall and winter. The drive for fruits amid winter has been noted for the geographic expansion of the mockingbird, and in particular, the fruit of Rosa multiflora, a favorite of the birds, is a possible link. Mockingbirds also eat garden fruits such as tomatoes, apples, and berries (like blackberries, raspberries, other bramble fruits, holly berries, mulberries, and dogwood), as well as grapes and figs.
These birds forage on the ground or in vegetation; they also fly down from a perch to capture food. While foraging, they frequently spread their wings in a peculiar two-step motion to display the white patches. There is disagreement among ornithologists over the purpose of this behavior, with hypotheses ranging from deceleration to intimidation of predators or prey.
Breeding
Both the male and female of the species reach sexual maturity after one year of life. The breeding season occurs in the spring and early summer. The males arrive before the beginning of the season to establish their territories. They may demonstrate or contest the edges of a territory using a boundary dance in which males, typically on the ground, face each other and hop side to side, sometimes fighting, until one flies away. The males use a series of courtship displays to attract the females to their sites. They run around the area either to showcase their territory to the females or to pursue the females. The males also engage in flight to showcase their wings. They sing and call as they perform all of these displays. The species can remain monogamous for many years, but incidents of polygyny and bigamy have been reported to occur during a single bird's lifetime.
Both the male and female are involved in the nest building. The male does most of the work, while the female perches on the shrub or tree where the nest is being built to watch for predators. The nest is built approximately three to ten feet above the ground. The outer part of the nest is composed of twigs, while the inner part is lined with grasses, dead leaves, moss, or artificial fibers. The eggs are a light blue or greenish color and speckled with dots. The female lays three to five eggs, and she incubates them for nearly two weeks. Once the eggs are hatched, both the male and female will feed the chicks.
The birds aggressively defend their nests and surrounding areas against other birds and animals. When a predator is persistent, mockingbirds from neighboring territories may be summoned by distinct calls to join the defense. Other birds may gather to watch as the mockingbirds drive away the intruder. In addition to harassing domestic cats and dogs that they consider a threat, mockingbirds will at times target humans. The birds are bold, and will attack much larger birds, even hawks. One incident in Tulsa, Oklahoma involving a postal carrier resulted in the distribution of a warning letter to residents.
The northern mockingbird pairs hatch about two to four broods a year. In one breeding attempt, the northern mockingbird lays an average of four eggs. They are pale blue or greenish white with red or brown blotches, and measure about . They hatch after about 11 to 14 days of incubation by the female. After about 10 to 15 days of life, the offspring become independent.
Sexual selection
Northern mockingbirds are famous for their song repertoires. Studies have shown that males sing songs at the beginning of breeding season to attract females. Unmated males sing songs in more directions and sing more bouts than mated males. In addition, unmated males perform more flight displays than mated males. The mockingbirds usually nest several times during one breeding season. Depending on the stage of breeding and the mating status, a male mockingbird will vary his song production. The unmated male keeps close track of this change. He sings in one direction when he perceives a chance to lure a female from the nest of the mated male. Unmated males are also more likely to use elevated perches to make their songs audible farther away. Though the mockingbirds are socially monogamous, mated males have been known to sing to attract additional mates.
An observational study by Logan demonstrates that the female is continuously evaluating the quality of the male and his territory. The assessment is usually triggered by the arrival of a new male in a neighboring territory at the beginning of a new breeding season. In those cases, the mated female is constantly seen flying over both the original and the new male's territory, evaluating the qualities of both territories and exchanging calls with both males. The social mate displays aggressive behaviors towards the female, while the new male shows less aggression and sings softer songs. At the same time, both the mated male and the new male will fly over other territories to attract other females as well. Separation, mate switching and extra-pair matings do occur in northern mockingbirds.
Sex allocation