Black stork
The black stork is a large bird in the stork family Ciconiidae. It was first described by Carl Linnaeus in the 10th edition of his Systema Naturae. Measuring on average from beak tip to end of tail with a wingspan, the adult black stork has mainly black plumage, with white underparts, long red legs and a long pointed red beak. A widespread but uncommon species, it breeds in scattered locations across Europe, and east across the Palearctic to the Pacific Ocean. It is a long-distance migrant, with European populations wintering in tropical Sub-Saharan Africa, and Asian populations in the Indian subcontinent. When migrating between Europe and Africa, it avoids crossing broad expanses of the Mediterranean Sea and detours via the Levant in the east, the Strait of Sicily in the center, or the Strait of Gibraltar in the west. An isolated non-migratory population lives in Southern Africa.
Unlike the closely related white stork, the black stork is a shy and wary species. It is seen singly or in pairs, usually in marshy areas, rivers or inland waters. It feeds on amphibians, small fish and insects, generally wading slowly in shallow water stalking its prey. Breeding pairs usually build nests in large forest trees—most commonly deciduous but also coniferous—which can be seen from long distances, as well as on large boulders, or under overhanging ledges in mountainous areas. The female lays two to five greyish-white eggs, which become soiled over time in the nest. Incubation takes 32 to 38 days, with both sexes sharing duties, and fledging takes 60 to 71 days.
The black stork is considered to be a species of least concern by the International Union for Conservation of Nature, but its actual status is uncertain. Despite its large range, it is nowhere abundant, and it appears to be declining in parts of its range, such as in India, China and parts of Western Europe, though increasing in others such as the Iberian Peninsula. Various conservation measures have been taken for the black stork, like the Conservation Action Plan for African black storks by Wetlands International. It is also protected under the African-Eurasian Waterbird Agreement and the Convention on International Trade in Endangered Species of Wild Fauna and Flora. On 31 May 1968, South Korea designated the species as natural monument 200.
Taxonomy and etymology
English naturalist Francis Willughby wrote about the black stork in the 17th century, having seen one in Frankfurt. He named it Ciconia nigra, from the Latin words for "stork" and "black" respectively. It was one of the many species originally described by Swedish zoologist Carl Linnaeus in the landmark 1758 10th edition of his Systema Naturae, where it was given the binomial name of Ardea nigra. It was moved to the new genus Ciconia by French zoologist Mathurin Jacques Brisson two years later. The word stork is derived from the Old English word storc, thought to be related to the Old High German storah, meaning "stork", and the Old English stearc, meaning "stiff".The black stork is a member of the genus Ciconia, or typical storks, a group of seven extant species, characterised by straight bills and mainly black and white plumage. The black stork was long thought to be most closely related to the white stork. However, genetic analysis via DNA–DNA hybridization and mitochondrial cytochrome b DNA by Beth Slikas in 1997 found that it was basal in the genus Ciconia. Fossil remains have been recovered from Miocene beds on Rusinga and Maboko Islands in Kenya, which are indistinguishable from the white and black storks.
Description
The black stork is a large bird, measuring between in length with a wingspan, and weighing around. Standing as tall as, it has long red legs, a long neck and a long, straight, pointed red beak. It bears some resemblance to Abdim's stork, which can be distinguished by its much smaller build, predominantly green bill, legs and feet, and white rump and lower back. The plumage is black with a purplish green sheen, except for the white lower breast, belly, armpits, axillaries and undertail coverts. The breast feathers are long and shaggy, forming a ruff which is used in some courtship displays. The black stork has brown irises, and bare red skin around its eyes. The sexes are identical in appearance, except that males are larger than females on average. Moulting takes place in spring, with the iridescent sheen brighter in new plumage. It walks slowly and steadily on the ground and like all storks, it flies with its neck outstretched.The juvenile resembles the adult in plumage, but the areas corresponding to the adult black feathers are browner and less glossy. The scapulars, wing and upper tail coverts have pale tips. The legs, bill and bare skin around the eyes are greyish green. It could possibly be confused with the juvenile yellow-billed stork, but the latter has paler wings and mantle, a longer bill and white under the wings.
Distribution and habitat
During the summer, the black stork is found from Eastern Asia west to Central Europe, reaching Estonia in the north, Poland, Lower Saxony and Bavaria in Germany, the Czech Republic, Hungary, Italy and Greece in the south, with an outlying population in the central-southwest region of the Iberian Peninsula. It is migratory, wintering in tropical Africa and Asia, although certain populations of black storks are sedentary or dispersive. An isolated population exists in Southern Africa, where the species is more numerous in the east, in eastern South Africa and Mozambique, and is also found in Zimbabwe, Eswatini, Botswana and less commonly Namibia.Most of the black storks that summer in Europe migrate to Africa, with those from western Germany and points west heading south via the Iberian Peninsula and the rest via Turkey and the Levant. Those flying via Spain spend winter in the Falémé River basin of eastern Senegal, Guinea, southern Mauritania, Ivory Coast, Sierra Leone and western and central Mali, while those flying via the Sinai end up in northern Ethiopia, the Kotto River basin in the Central African Republic, the Mbokou river basin in Chad and northeastern Nigeria. Black storks summering in West Asia migrate to northern and northeastern India, ranging mainly from Punjab south to Karnataka, and Africa. They are occasional visitors to Sri Lanka. Those summering further east in eastern Russia and China winter mainly in southern China, and occasionally in Hong Kong, Myanmar, northern Thailand, and Laos. They were first recorded in western Myanmar in 1998.
The black stork prefers more wooded areas than the better-known white stork, and breeds in large marshy wetlands with interspersed coniferous or broadleaved woodlands, but also inhabits hills and mountains with sufficient networks of creeks. It usually inhabits ponds, rivers, edges of lakes, estuaries and other freshwater wetlands. The black stork does inhabit more agricultural areas in the Caspian lowlands, but even here it avoids close contact with people. Its wintering habitat in India comprises reservoirs or rivers with nearby scrub or forest, which provide trees that black storks can roost in at night. In southern Africa it is found in shallow water in rivers or lakes, or swamps, but is occasionally encountered on dry land.
After disappearing from Belgium before the onset of the 20th century, it has returned to breed in the Belgian Ardennes, Luxembourg and Burgundy, France, by 2000. It appears to be increasing in numbers in Spain and Portugal, where the population was estimated at 405 to 483 pairs in 2006. The black stork is a rare vagrant to the British Isles, turning up in the warmer months—particularly in spring—generally in the south and east. Sightings have become more common since the 1970s as its breeding range moves northwards. It has been recorded in Scotland six times between 1946 and 1983, including from Shetland, Orkney and the Highlands, as well as the Scottish Borders. It is not abundant in the western parts of its distribution, but more densely inhabits eastern Transcaucasia. Further east, it has been recorded from locations across Iran, though little is known about its habits there; breeding has been recorded from near Aliabad in Fars province, Khabr National Park in Kerman province, Karun river in Khuzestan province, Qaranqu River in East Azarbaijan province, and Aliabad river in Razavi Khorasan province. The population has declined in Iran due to draining of wetlands. East of the Ural Mountains, the black stork is patchily found in forested and mountainous areas up to 60°‒63° N across Siberia to the Pacific Ocean. South of Siberia, it breeds in Xinjiang, northwestern China, northern Mongolia south to the Altai Mountains, and northeastern China south to the vicinity of Beijing. In the Korean peninsula, the black stork is an uncommon summer visitor, no longer breeding in the south since 1966. Birds have been seen in the northeast but it is not known whether they breed there. Similarly it has been seen in the summer in Afghanistan, but its breeding status is uncertain.
Migration
Migration takes place from early August to October, with a major exodus in September. Some of the Iberian populations, and also those in southern Africa, are essentially non-migratory, though they may wander freely in the non-breeding areas. A broad-winged soaring bird, the black stork is assisted by thermals of hot air for long-distance flight, although is less dependent on them than is the white stork. Since thermals only form over land, the black stork, together with large raptors, must cross the Mediterranean at the narrowest points, and many black storks travel south through the Bosphorus and on through the Sinai, as well as through Gibraltar. The trip is around via the western route and via the eastern route, with satellite tracking yielding an average travel time of 37 and 80 days respectively. The western route goes over the Rock of Gibraltar or over the Bay of Gibraltar, generally on a southwesterly track that takes them to the central part of the strait, from where they reach Morocco. Many birds then fly around the Sahara next to the coast. About 10% of the western storks choose the passage between Sicily and Cap Bon, crossing the 145 km wide Strait of Sicily.Spain contains several important areas—Monfragüe National Park, Sierra de Gredos Regional Park, National Hunting Reserve in Cíjara, Natural Park of the Sierra Hornachuelos and Doñana National Park—where black storks stop over on the western migration route. Pesticide use has threatened birdlife in nearby Doñana. Further south, Lake Faguibine in Mali is another stopover point but it has been affected by drought in recent years.