About Sturnus vulgaris Linnaeus, 1758
The common starling (Sturnus vulgaris Linnaeus, 1758) measures 19–23 cm (7.5–9.1 in) in length, has a 31–44 cm (12–17 in) wingspan, and weighs 58–101 g (2.0–3.6 oz). Its standard body measurements are: wing chord 11.8 to 13.8 cm (4.6 to 5.4 in), tail 5.8 to 6.8 cm (2.3 to 2.7 in), culmen 2.5 to 3.2 cm (0.98 to 1.26 in), and tarsus 2.7 to 3.2 cm (1.1 to 1.3 in).
Its plumage is iridescent black with purple or green gloss, and is spangled with white, with more prominent white spangling in winter. At the same time of year, adult males have fewer spots on their underparts than adult females. Male common starlings have long, loose throat feathers used for display, while females have smaller, more pointed throat feathers. Their legs are stout; they are pinkish- or greyish-red during the breeding season, and slightly darker in winter. The bill is narrow, conical, and has a sharp tip. In winter the bill is brownish-black; in summer, females have lemon yellow beaks with pink bases, while males have yellow bills with blue-grey bases.
Common starlings moult once a year in late summer, after the breeding season ends. Fresh feathers after moulting have prominent white tips on breast feathers, and buff tips on wing and back feathers, which gives the bird a speckled appearance. Spotting fades during the breeding season as the light-colored feather tips mostly wear away. Juveniles are grey-brown, and by their first winter they resemble adults, though they often retain some brown juvenile feathering, especially on the head.
Sex can usually be determined by iris color: males have rich brown irises, while females have mouse-brown or grey irises. Estimating the contrast between the iris and the permanently dark central pupil is 97% accurate for sexing, and accuracy rises to 98% when throat feather length is also considered.
The common starling is mid-sized for both starling and passerine species. It is easily distinguished from most other mid-sized passerines such as thrushes, icterids, or small corvids by its relatively short tail, sharp blade-like bill, round-bellied shape, and strong, sizeable rufous-colored legs. In flight, its strongly pointed wings and dark colour are distinctive, while on the ground its characteristic somewhat waddling gait also sets it apart. Its colouring and body structure usually distinguish it from other starlings, though the closely related spotless starling can be told apart by its lack of pale feather tip spots in adult breeding plumage. The Bohemian waxwing is structurally very similar in flight and also flies in dense flocks, but can be distinguished by its paler reddish buff colour, slightly smaller size, and very different flight call.
Like most terrestrial starlings, the common starling moves by walking or running rather than hopping. Its flight is strong and direct; its triangular wings beat very rapidly, and periodically birds glide for a short distance without losing much height before resuming powered flight. When in a flock, birds take off almost simultaneously, wheel and turn in unison, form a compact mass or trail off into a wispy stream, then bunch up again and land in a coordinated fashion. Migrating common starlings can fly at 60–80 km/h (37–50 mph) and cover up to 1,000–1,500 km (620–930 mi).
Several terrestrial starlings, including those in the genus Sturnus, have skull and muscle adaptations that support feeding by probing. This adaptation is most strongly developed in the common starling (along with the spotless and white-cheeked starlings): the protractor muscles that open the jaw are enlarged, and the skull is narrow, allowing the eye to move forward to peer down the length of the bill. The probing technique involves inserting the bill into the ground and opening it to search for hidden food. The physical traits that allow this feeding technique have helped the common starling spread widely across the globe.
In Iberia, the western Mediterranean, and northwest Africa, the common starling may be confused with the closely related spotless starling, which, as its name suggests, has more uniformly colored plumage. At close range, spotless starlings can be identified by their longer throat feathers, a feature that is particularly noticeable when the bird sings.
In 2004, the global common starling population was estimated at 310 million individuals, occupying a total range of 8,870,000 km2 (3,420,000 sq mi). Widespread across the Northern Hemisphere, the species is native to Eurasia, and found throughout Europe, northern Africa from Morocco to Egypt, India (mainly in the north, but regularly extending further south and into the Maldives), Nepal, the Middle East including Israel, Syria, Iran, and Iraq, and northwestern China. Common starlings in southern and western Europe and south of 40°N are mainly resident, while other populations migrate from regions with harsh winters, frozen ground, and scarce food. Large numbers of common starlings from northern Europe, Russia, and Ukraine migrate southwest or southeast. In autumn, while immigrants arrive from eastern Europe, many of Britain's common starlings depart for Iberia and North Africa; different groups of birds pass through the country, and their migration pathways may cross. Of 15,000 birds ringed as nestlings in Merseyside, England, individuals have been recovered at various times of year as far afield as Norway, Sweden, Finland, Russia, Ukraine, Poland, Germany, and the Low Countries. Small numbers of common starlings have been spotted sporadically in Japan and Hong Kong, but the origin of these birds is unclear. In North America, northern populations have developed a migration pattern, leaving most of Canada during winter; birds in eastern North America move south, while birds from farther west winter in the southwestern United States.
Common starlings prefer urban or suburban areas, where artificial structures and trees provide suitable nesting and roosting sites. They also favour reedbeds for roosting, and commonly feed in grassy areas such as farmland, grazing pastures, playing fields, golf courses, and airfields, where short grass makes foraging easy. They occasionally live in open forests and woodlands, and are sometimes found in shrubby areas such as Australian heathland. They rarely inhabit dense, wet forests such as rainforests or wet sclerophyll forests, but are found in coastal areas, where they nest and roost on cliffs and forage among seaweed. Their ability to adapt to a wide variety of habitats has allowed them to disperse and establish populations in diverse locations around the world, with a habitat range extending from coastal wetlands to alpine forests, and from sea cliffs to mountain ranges 1,900 m (6,200 ft) above sea level.
The common starling is a highly gregarious species, especially in autumn and winter. While flock size varies greatly, large noisy flocks called murmurations may form near roosts. These dense bird concentrations are thought to provide defence against attacks by birds of prey such as peregrine falcons or Eurasian sparrowhawks. Flocks form tight sphere-like formations in flight, frequently expanding, contracting, and changing shape, with no apparent leader. Each common starling adjusts its course and speed in response to the movement of its closest neighbours.
Very large roosts, holding up to 1.5 million birds, form in city centres, woodlands, and reedbeds, and cause issues from accumulated bird droppings. Droppings can build up to 30 cm (12 in) deep, and kill trees via their concentrated chemical content. In smaller amounts, droppings act as fertiliser, so woodland managers may move roosts from one area of woodland to another to gain the benefit of soil enhancement and avoid large toxic deposits. Flocks of more than a million common starlings may be observed just before sunset in spring in southwestern Jutland, Denmark, over the seaward marshlands of Tønder and Esbjerg municipalities between Tønder and Ribe. The birds gather here starting in March, until northern Scandinavian birds depart for their breeding ranges by mid-April. Their swarming behaviour creates complex shapes silhouetted against the sky, a phenomenon locally called sort sol meaning "black sun". Flocks of 5,000 to 50,000 common starlings form in areas of the United Kingdom just before sundown during mid-winter, and these flocks are commonly called murmurations.
