Slightly smaller than the white stork, the black stork is a large bird, 95 to 100 cm (37 to 39 in) in length with a 145–155 cm (4.76–5.09 ft) wingspan, and weighing around 3 kg (6.6 lb). They can stand as tall as 102 cm (40 in). 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 black stork is a strong migrant, wintering in tropical Africa, India & Bangladesh. A broad-winged soaring bird, the black stork is assisted by thermals of hot air for long distance flight, although are less dependent on them than the white stork. Since thermals only form over land, storks must cross the Mediterranean at the narrowest points, and many black storks can be seen going through the Bosphorus. They fly approximately 100 to 250 km (62 to 155 mi) a day with daily maxima up to 500 km (310 mi).