The common starling (Sturnus vulgaris), also known as the European starling in the United States or simply the starling in the British Isles, is a medium-sized passerine bird in the starling family, Sturnidae. It is about 20 cm (8 in) long and has glossy black plumage with a metallic sheen, which is speckled with white at some times of year. The legs are pink and the bill is black in winter and yellow in summer; young birds have browner plumage than the adults. It is a noisy bird, especially in communal roosts and other gregarious situations, with an unmusical but varied song. Its gift for mimicry has been noted in literature including the Mabinogion and the works of Pliny the Elder and William Shakespeare.
The common starling has about 12 subspecies breeding in open habitats across its native range in temperate Europe and across the Palearctic to western Mongolia, and it has been introduced to Australia, New Zealand, Canada, the United States, Mexico, Argentina, South Africa and Fiji. This bird is resident in western and southern Europe and southwestern Asia, while northeastern populations migrate south and west in the winter within the breeding range and also further south to Iberia and North Africa. The common starling builds an untidy nest in a natural or artificial cavity in which four or five glossy, pale blue eggs are laid. These take two weeks to hatch and the young remain in the nest for another three weeks. There are normally one or two breeding attempts each year. This species is omnivorous, taking a wide range of invertebrates, as well as seeds and fruit. It is hunted by various mammals and birds of prey, and is host to a range of external and internal parasites.
Large flocks typical of this species can be beneficial to agriculture by controlling invertebrate pests; however, starlings can also be pests themselves when they feed on fruit and sprouting crops. Common starlings may also be a nuisance through the noise and mess caused by their large urban roosts. Introduced populations in particular have been subjected to a range of controls, including culling, but these have had limited success, except in preventing the colonisation of Western Australia.
The species has declined in numbers in parts of northern and western Europe since the 1980s due to fewer grassland invertebrates being available as food for growing chicks. Despite this, its huge global population is not thought to be declining significantly, so the common starling is classified as being of Least Concern by the International Union for Conservation of Nature.
Description & appearanceThe common starling is 19–23 cm (7.5–9.1 in) long, with a wingspan of 31–44 cm (12–17 in) and a weight of 58–101 g (2.0–3.6 oz). Among standard measurements, the wing chord is 11.8 to 13.8 cm (4.6 to 5.4 in), the tail is 5.8 to 6.8 cm (2.3 to 2.7 in), the culmen is 2.5 to 3.2 cm (0.98 to 1.26 in) and the tarsus is 2.7 to 3.2 cm (1.1 to 1.3 in). The plumage is iridescent black, glossed purple or green, and spangled with white, especially in winter. The underparts of adult male common starlings are less spotted than those of adult females at a given time of year. The throat feathers of males are long and loose and are used in display while those of females are smaller and more pointed. The legs are stout and pinkish- or greyish-red. The bill is narrow and conical with a sharp tip; in the winter it is brownish-black but in summer, females have lemon yellow beaks while males have yellow bills with blue-grey bases. Moulting occurs once a year- in late summer after the breeding season has finished; the fresh feathers are prominently tipped white (breast feathers) or buff (wing and back feathers), which gives the bird a speckled appearance. The reduction in the spotting in the breeding season is achieved through the white feather tips largely wearing off. Juveniles are grey-brown and by their first winter resemble adults though often retaining some brown juvenile feathering, especially on the head.
They can usually be sexed by the colour of the irises, rich brown in males, mouse-brown or grey in females. Estimating the contrast between an iris and the central always-dark pupil is 97% accurate in determining sex, rising to 98% if the length of the throat feathers is also considered. The common starling is mid-sized by both starling standards and passerine standards. It is readily distinguished from 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 (and rufous-coloured) legs. In flight, its strongly pointed wings and dark colouration are distinctive, while on the ground its strange, somewhat waddling gait is also characteristic. The colouring and build usually distinguish this bird from other starlings, although the closely related spotless starling may be physically distinguished by the lack of iridescent spots in adult breeding plumage.
Like most terrestrial starlings the common starling moves by walking or running, rather than hopping. Their flight is quite strong and direct; their triangular-shaped wings beat very rapidly, and periodically the birds glide for a short way without losing much height before resuming powered flight. When in a flock, the birds take off almost simultaneously, wheel and turn in unison, form a compact mass or trail off into a wispy stream, bunch up again and land in a coordinated fashion. Common starling on migration 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 adaptations of the skull and muscles that help with feeding by probing. This adaptation is most strongly developed in the common starling (along with the spotless and white-cheeked starlings), where the protractor muscles responsible for opening the jaw are enlarged and the skull is narrow, allowing the eye to be moved forward to peer down the length of the bill. This technique involves inserting the bill into the ground and opening it as a way of searching for hidden food items. Common starlings have the physical traits that enable them to use this feeding technique, which has undoubtedly helped the species spread far and wide.
In Iberia, the western Mediterranean and northwest Africa, the common starling may be confused with the closely related spotless starling, the plumage of which, as its name implies, has a more uniform colour. At close range it can be seen that the latter has longer throat feathers, a fact particularly noticeable when it sings.
Voice, singing & callThe common starling is a noisy bird. Its song consists of a wide variety of both melodic and mechanical-sounding noises as part of a ritual succession of sounds. The male is the main songster and engages in bouts of song lasting for a minute or more. Each of these typically includes four varieties of song type, which follow each other in a regular order without pause. The bout starts with a series of pure-tone whistles and these are followed by the main part of the song, a number of variable sequences that often incorporate snatches of song mimicked from other species of bird and various naturally occurring or man-made noises. The structure and simplicity of the sound mimicked is of greater importance than the frequency with which it occurs. In some instances, a wild starling has been observed to mimic a sound it has heard only once. Each sound clip is repeated several times before the bird moves on to the next. After this variable section comes a number of types of repeated clicks followed by a final burst of high-frequency song, again formed of several types. Each bird has its own repertoire with more proficient birds having a range of up to 35 variable song types and as many as 14 types of clicks.
Males sing constantly as the breeding period approaches and perform less often once pairs have bonded. In the presence of a female, a male sometimes flies to his nest and sings from the entrance, apparently attempting to entice the female in. Older birds tend to have a wider repertoire than younger ones. Those males that engage in longer bouts of singing and that have wider repertoires attract mates earlier and have greater reproductive success than others. Females appear to prefer mates with more complex songs, perhaps because this indicates greater experience or longevity. Having a complex song is also useful in defending a territory and deterring less experienced males from encroaching.
Singing also occurs outside the breeding season, taking place throughout the year apart from the moulting period. The songsters are more commonly male although females also sing on occasion. The function of such out-of-season song is poorly understood. Eleven other types of call have been described including a flock call, threat call, attack call, snarl call and copulation call. The alarm call is a harsh scream, and while foraging together common starlings squabble incessantly. They chatter while roosting and bathing, making a great deal of noise that can cause irritation to people living nearby. When a flock of common starlings is flying together, the synchronised movements of the birds' wings make a distinctive whooshing sound that can be heard hundreds of metres away.
Distribution & habitatThe global population of common starlings was estimated to be 310 million individuals in 2004, occupying a total area of 8,870,000 km2 (3,420,000 sq mi). Widespread throughout the Northern Hemisphere, the bird is native to Eurasia and is found throughout Europe, northern Africa (from Morocco to Egypt), India (mainly in the north but regularly extending further south and extending into the Maldives) Nepal, the Middle East including Syria, Iran, and Iraq and north-western China.
Common starlings in the south and west of Europe and south of latitude 40°N are mainly resident, although other populations migrate from regions where the winter is harsh, the ground frozen and food scarce. Large numbers of birds from northern Europe, Russia and Ukraine migrate south westwards or south eastwards. In the autumn, when immigrants are arriving from eastern Europe, many of Britain's common starlings are setting off for Iberia and North Africa. Other groups of birds are in passage across the country and the pathways of these different streams of bird may cross. Of the 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 starling have sporadically been observed in Japan and Hong Kong but it is unclear from where these birds originated. In North America, northern populations have developed a migration pattern, vacating much of Canada in winter. Birds in the east of the country move southwards, and those from further west winter in the southwest of the US.
Common starlings prefer urban or suburban areas where artificial structures and trees provide adequate nesting and roosting sites. Reedbeds are also favoured for roosting and the birds commonly feed in grassy areas such as farmland, grazing pastures, playing fields, golf courses and airfields where short grass makes foraging easy. They occasionally inhabit open forests and woodlands and are sometimes found in shrubby areas such as Australian heathland. Common starlings rarely inhabit dense, wet forests (i.e. rainforests or wet sclerophyll forests) but are found in coastal areas, where they nest and roost on cliffs and forage amongst seaweed. Their ability to adapt to a large variety of habitats has allowed them to disperse and establish themselves in diverse locations around the world resulting in a habitat range from coastal wetlands to alpine forests, from sea cliffs to mountain ranges 1,900 m (6,200 ft) above sea level.
Hunting & foodThe common starling is largely insectivorous and feeds on both pest and other arthropods. The food range includes spiders, crane flies, moths, mayflies, dragonflies, damsel flies, grasshoppers, earwigs, lacewings, caddisflies, flies, beetles, sawflies, bees, wasps and ants. Prey are consumed in both adult and larvae stages of development, and common starlings will also feed on earthworms, snails, small amphibians and lizards. While the consumption of invertebrates is necessary for successful breeding, common starlings are omnivorous and can also eat grains, seeds, fruits, nectar and food waste if the opportunity arises. The Sturnidae differ from most birds in that they cannot easily metabolise foods containing high levels of sucrose, although they can cope with other fruits such as grapes and cherries. The isolated Azores subspecies of the common starling eats the eggs of the endangered roseate tern. Measures are being introduced to reduce common starling populations by culling before the terns return to their breeding colonies in spring.
There are several methods by which common starlings obtain their food but for the most part, they forage close to the ground, taking insects from the surface or just underneath. Generally, common starlings prefer foraging amongst short-cropped grasses and eat with grazing animals or perch on their backs, where they will also feed on the mammal's external parasites. Large flocks may engage in a practice known as "roller-feeding", where the birds at the back of the flock continually fly to the front where the feeding opportunities are best. The larger the flock, the nearer individuals are to one another while foraging. Flocks often feed in one place for some time, and return to previous successfully foraged sites.
There are three types of foraging behaviour observed in the common starling. "Probing" involves the bird plunging its beak into the ground randomly and repetitively until an insect has been found, and is often accompanied by bill gaping where the bird opens its beak in the soil to enlarge a hole. This behaviour, first described by Konrad Lorenz and given the German term zirkeln, is also used to create and widen holes in plastic garbage bags. It takes time for young common starlings to perfect this technique, and because of this the diet of young birds will often contain fewer insects. "Hawking" is the capture of flying insects directly from the air, and "lunging" is the less common technique of striking forward to catch a moving invertebrate on the ground. Earthworms are caught by pulling from soil. Common starlings that have periods without access to food, or have a reduction in the hours of light available for feeding, compensate by increasing their body mass by the deposition of fat.[
Breeding & matingUnpaired males find a suitable cavity and begin to build nests in order to attract single females, often decorating the nest with ornaments such as flowers and fresh green material, which the female later disassembles upon accepting him as a mate. The amount of green material is not important, as long as some is present, but the presence of herbs in the decorative material appears to be significant in attracting a mate. The scent of plants such as yarrow acts as an olfactory attractant to females.
The males sing throughout much of the construction and even more so when a female approaches his nest. Following copulation, the male and female continue to build the nest. Nests may be in any type of hole, common locations include inside hollowed trees, buildings, tree stumps and man-made nest-boxes. S. v. zetlandicus typically breeds in crevices and holes in cliffs, a habitat only rarely used by the nominate form. Nests are typically made out of straw, dry grass and twigs with an inner lining made up of feathers, wool and soft leaves. Construction usually takes four or five days and may continue through incubation.
Common starlings are both monogamous and polygamous; although broods are generally brought up by one male and one female, occasionally the pair may have an extra helper. Pairs may be part of a colony, in which case several other nests may occupy the same or nearby trees. Males may mate with a second female while the first is still on the nest. The reproductive success of the bird is poorer in the second nest than it is in the primary nest and is better when the male remains monogamous.
Breeding takes place during the spring and summer. Following copulation, the female lays eggs on a daily basis over a period of several days. If an egg is lost during this time, she will lay another to replace it. There are normally four or five eggs that are ovoid in shape and pale blue or occasionally white, and they commonly have a glossy appearance. The colour of the eggs seems to have evolved through the relatively good visibility of blue at low light levels. The egg size is 26.5–34.5 mm (1.04–1.36 in) in length and 20.0–22.5 mm (0.79–0.89 in) in maximum diameter.
Chicks, juveniles & raiseIncubation lasts thirteen days, although the last egg laid may take 24 hours longer than the first to hatch. Both parents share the responsibility of brooding the eggs, but the female spends more time incubating them than does the male, and is the only parent to do so at night when the male returns to the communal roost. The young are born blind and naked. They develop light fluffy down within seven days of hatching and can see within nine days.
Once the chicks are able to regulate their body temperature, about six days after hatching, the adults largely cease removing droppings from the nest. Prior to that, the fouling would wet both the chicks' plumage and the nest material, thereby reducing their effectiveness as insulation and increasing the risk of chilling the hatchlings. Nestlings remain in the nest for three weeks, where they are fed continuously by both parents. Fledglings continue to be fed by their parents for another one or two weeks. A pair can raise up to three broods per year, frequently reusing and relining the same nest, although two broods is typical, or just one north of 48°N. Within two months, most juveniles will have moulted and gained their first basic plumage. They acquire their adult plumage the following year. As with other passerines, the nest is kept clean and the chicks' faecal sacs are removed by the adults.
Intraspecific brood parasites are common in common starling nests. Female "floaters" (unpaired females during the breeding season) present in colonies often lay eggs in another pair's nest. Fledglings have also been reported to invade their own or neighbouring nests and evict a new brood. Common starling nests have a 48% to 79% rate of successful fledging, although only 20% of nestlings survive to breeding age; the adult survival rate is closer to 60%. The average life span is about 2–3 years, with a longevity record of 22 yr 11 m.