The black kite (Milvus migrans) is a medium-sized bird of prey in the family Accipitridae, which also includes many other diurnal raptors. It is thought to be the world's most abundant species of Accipitridae, although some populations have experienced dramatic declines or fluctuations. Current global population estimates run up to 6 million individuals.
Unlike others of the group, black kites are opportunistic hunters and are more likely to scavenge. They spend much time soaring and gliding in thermals in search of food. Their angled wing and distinctive forked tail make them easy to identify. They are also vociferous with a shrill whinnying call.
The black kite is widely distributed through the temperate and tropical parts of Eurasia and parts of Australasia and Oceania, with the temperate region populations tending to be migratory. Several subspecies are recognized and formerly had their own English names. The European populations are small, but the South Asian population is very large.
Black kites can be distinguished from red kites by the slightly smaller size, less forked tail (visible in flight), and generally dark plumage without any rufous. The sexes are alike though the male is a little smaller and less aggressive (this is the case in most birds of prey). They weigh on average 735 grams. The upper plumage is brown but the head and neck tend to be paler. The patch behind the eye appears darker. The outer flight feathers are black and the feathers have dark cross bars and are mottled at the base. The lower parts of the body are pale brown, becoming lighter towards the chin. The body feathers have dark shafts giving it a streaked appearance. The cere and gape are yellow, but the bill is black (unlike that of the yellow-billed kite). The legs are yellow and the claws are black. They have a distinctive shrill whistle followed by a rapid whinnying call. Males and females have the same plumage but females are longer than males and have a little larger wingspan. Their wingspan is around 150 cm.
The species is not found in the Indonesian archipelago between the South East Asian mainland and the Wallace Line. Vagrants, most likely of the black-eared kite, on occasion range far into the Pacific, out to the Hawaiian islands.
In India, the population of M. m. govinda is particularly large especially in areas of high human population. Here the birds avoid heavily forested regions. A survey in 1967 in the 150 square kilometres of the city of New Delhi produced an estimate of about 2200 pairs or roughly 15 per square kilometre. Another survey in 2013 estimated 150 pairs for every 10 square kilometres.
Vagrants from Australia occasionally reach New Zealand, however, only one individual has persisted there (currently ~21 years old).
The species is found in Europe, Asia, Africa and Australia. The temperate populations of this kite tend to be migratory while the tropical ones are resident. European and central Asian birds (subspecies M. m. migrans and black-eared kite M. m. lineatus, respectively) are migratory, moving to the tropics in winter, but races in warmer regions such as the Indian M. m. govinda (small Indian/pariah kite), or the Australasian M. m. affinis (fork-tailed kite), are resident. In some areas such as in the United Kingdom, the black kite occurs only as a wanderer on migration. These birds are usually of the nominate race, but in November 2006 a juvenile of the eastern lineatus, not previously recorded in western Europe, was found in Lincolnshire.
Black kites are most often seen gliding and soaring on thermals as they search for food. Their flight is buoyant and the bird glides effortlessly, changing directions easily. They will swoop down with their legs lowered to snatch small live prey, fish, household refuse and carrion, for which behaviour they are known in British military slang as the shite-hawk. They are opportunist hunters and have been known to take birds, bats, and rodents. They are attracted to smoke and fires, where they seek escaping prey. Kites are also known to spread fires by picking and dropping burning twigs so as to flush prey, leading to them being known in some circles as "firehawks". The Indian populations are well adapted to living in cities and are found in densely populated areas. Large numbers may be seen soaring in thermals over cities. In some places, they will readily swoop and snatch food held by humans. In Delhi, where black kites breed within the cities, religious offerings of meat to the kites are common among those who practice Islam. The meat is thrown into the air and the kites dive-bomb for the meat. Humans who are in the vicinity may suffer serious injury due to the sharp talons of the kites. The reinforcement between human proximity and being fed have decreased the kite's fear of humans. Black kites in Spain prey on nestling waterfowl especially during summer to feed their young. Predation of nests of other pairs of black kites has also been noted. Kites have also been seen to tear and carry away the nests of baya weavers in an attempt to obtain eggs or chicks.
In winter, kites form large communal roosts. Flocks may fly about before settling at the roost. When migrating, the black kite has a greater propensity to form large flocks than other migratory raptors, particularly prior to making a crossing over water. In India, the subspecies govinda shows large seasonal fluctuations with the highest numbers seen from July to October, after the monsoons, and it has been suggested that they make local movements in response to high rainfall.