The Black Stork (Ciconia nigra) is a large wading bird in the stork family Ciconiidae. It is a widespread, but rare, species that breeds in the warmer parts of Europe, predominantly in central and eastern regions. This is a shy and wary species, unlike the closely related White Stork. It is seen in pairs or small flocks—in marshy areas, rivers or inland waters. The Black Stork feeds on amphibians and insects.
Slightly smaller than the White Stork, the Black Stork is a large bird, 95 to 100 cm (37–39 in) in length with a 145–155 cm (5 ft) wingspan, and weighing around 3 kilograms (6.6 lb). Like all storks, it has long legs, a long neck, and a long, straight, pointed beak. The plumage is all black with a purplish green sheen, except for the white lower breast, belly, axillaries and undertail coverts. The breast feathers are long and shaggy forming a ruff which is used in some courtship displays. The bare skin around its eyes is red, as are its red bill and legs. The sexes are identical in appearance, except that males are larger than females on average.
The juvenile resembles the adult in plumage pattern, 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 may be confused with the juvenile Yellow-billed Stork, but the latter has a paler wings and mantle, longer bill, and white under the wings.
It walks slowly and steadily on the ground. Like all storks, it flies with its neck outstretched. It has a rasping call, but rarely indulges in mutual bill-clattering when adults meet at the nest.
During the summer, the Black Stork is found from Eastern Asia (Siberia and China) west to Central Europe, reaching Estonia in the north, Poland, Lower Saxony and Bavaria in Germany, Czech Republic, Hungary, and Greece in the south, with an outlying population in Spain. They are nowhere abundant in these western parts of their distribution, but more densely inhabit the eastern Transcaucasus.
Preferring more wooded areas than the better known White Stork, the Black Stork breeds in large marshy wetlands with interspersed coniferous or broadleaved woodlands, but also inhabits hills and mountains with sufficient network of creeks. It does inhabit more areas in the Caspian lowlands.
The Black Stork is a strong migrant, wintering in tropical Africa and India. However, the Iberian population is resident. A broad-winged soaring bird, the Black Stork is assisted by thermals of hot air for long distance flight, altohugh are less dependent on them than the White Stork. Since thermals only form over land, storks, together with large raptors, must cross the Mediterranean at the narrowest points, and many Black Storks can be seen going through the Bosporus. They fly approximately 100 to 250 km a day with daily maxima up to 500 km.
Black Stork parents have been known to kill one of their young, generally the smallest, in times of food shortage to reduce brood size and hence increase the chance of survival of the remaining nestlings. Stork nestlings do not attack each other, and their parents' method of feeding them (disgorging large amounts of food at once) means that stronger siblings cannot outcompete weaker ones for food directly, hence parental infanticide is an efficient way of reducing brood size. Despite this, this behaviour has not commonly been observed.