Black kite

Name and taxonomy

Buffon described the bird in his natural history of birds in 1770, without giving it a scientific name. The Dutch naturalist Pieter Boddaert supplied the name Falco migrans in 1783. Bernard Germain de Lacepede set up the genus Milvus in 1799. Milvus is a Latin name for the red kite, and migrans means migrating. The type specimen came from France.

The English word kite comes from cyta in Old English, a name that copies the call. The word first belonged to the buzzard, and it moved across to the red kite around the 1700s. British service personnel in the tropics called the black kite a shite-hawk, after its taste for refuse. Other names in use include fire kite, fork-tailed kite and black-eared kite. The old name pariah kite came from the Indian caste system and is no longer used.

Evolution and relatives

The genus Milvus holds the black kite, the red kite and the yellow-billed kite. Kites as a whole form no single natural group, and the label sits on several branches of the hawk family. The red kite and the black kite have produced hybrids in captivity and on the Cape Verde Islands. DNA work separates the yellow-billed African birds from the Eurasian ones. Many authorities now treat those African birds as a species of their own.

Five subspecies of the black kite are recognised. The European bird breeds from Europe to the Tien Shan and winters south of the Sahara. The black-eared kite runs from Siberia to Japan and south around the Himalayas. The small Indian kite is resident from Pakistan to the Malay Peninsula. The fork-tailed kite lives in New Guinea and eastern Australia, and a fifth race holds Taiwan and Hainan. The Taiwan birds are now probably a blend of that race and the black-eared kite.

Appearance

The body measures 47 to 60 cm, with an average of about 55 cm. The wingspan runs from 140 to 150 cm. Birds average about 735 g, and Animal Diversity Web gives a lighter 560 g. The sexes wear the same plumage. The female is a little longer than the male and has a slightly wider span.

The upperside is brown and darkens towards the wingtips and the tail. The head and neck are paler, and a darker patch sits behind the eye. The outermost flight feathers are black, and the rest carry dark bars across them. Dark shafts in the body feathers give the underside a streaked look. The underparts are pale brown and grow lighter towards the chin.

The bill is black and strongly hooked, and the cere and gape are yellow. That black bill separates the species from the yellow-billed kite of Africa. The legs are yellow, and the claws on them are black. The eyes are small, dark and bead-like. The tail forks shallowly, less deeply than the tail of a red kite. A young bird is paler and its tail fork is shorter.

Habitat and range

The species covers Europe, Asia, Africa and Australia. It is missing from the Indonesian islands between mainland Southeast Asia and the Wallace Line. Stray black-eared kites have reached as far east as Hawaii. In Britain the bird appears only as a wanderer on migration. A juvenile of the eastern race turned up in Lincolnshire in November 2006, the first for western Europe.

Open ground near water is the core habitat. River edges, ponds, lakes and wetlands all draw the bird. It also uses woodland edges, open savanna and farmland. It avoids dense forest, true desert and high mountains. Cities suit it, because rats and roadkill are steady food.

Temperate populations migrate and tropical ones stay put. European and central Asian birds move to the tropics for the winter. Indian and Australian birds hold their ground all year. Indian numbers rise sharply from July to October, after the monsoon. A survey of New Delhi in 1967 found about 2200 pairs in 150 square kilometres. A later survey in 2013 counted 150 pairs for every 10 square kilometres.

Diet and hunting

The black kite eats almost anything it can carry. Carrion, refuse, roadkill and dead fish make up much of the diet. It also kills rodents, bats, small birds, lizards, frogs and insects. It robs other kites' nests and has torn open weaver nests to reach the eggs and chicks. Black kites in Spain take young waterfowl, especially while feeding their own brood.

Most of the day is spent gliding on thermals with the wings held at an angle. The flight is buoyant, and the bird changes direction with a twist of the tail. It drops with its legs lowered to snatch food from the ground or the water surface. Sight is its main sense, and it can pick out food at a great distance. In cities it will take meat from a person's hand or from the air.

Fire is a hunting tool as well as a signal. Kites collect over smoke and along a fire front to catch the animals that run out. In northern Australia they carry burning sticks and drop them in unburnt grass. The new fire flushes more prey, and this habit has earned the birds the name firehawks. In some Indian towns people throw meat into the air for the kites to catch. That habit has made the birds bold, and their talons have caused serious injuries.

Behaviour and social life

The black kite is social for most of the year. In winter it gathers in large communal roosts, and flocks circle before they settle. On migration it forms bigger flocks than most other travelling raptors. Those flocks build up before a crossing over open water. During the breeding season a pair may live alone or in a loose group.

The bird is loud and calls often, both at the roost and while hunting. A pair defends the ground around its nest and watches for anything that comes near. Away from the nest it holds no territory that anyone has measured. Its home range sits close to the roost when it is not travelling. Among chicks, rank follows hatching order and egg size, and the first out leads.

Communication and senses

The call is a long shrill whistle that runs into a fast whinnying trill. Animal Diversity Web writes the first part as a drawn-out kleee-errr. The second part breaks into a sharper repeated note. Birds call at the roost, in courtship and while hunting in company. The calls resemble those of the red kite, and captive birds of the two species answer each other.

Courtship is loud and acrobatic. A pair grapples in the air, locking their feet together and spinning down towards the ground. The two birds probably break apart well before they reach the ground. Eyesight is the leading sense and finds food far below. Some nests are decorated with white plastic, and a Spanish study reads that as a warning to rival kites.

Reproduction and life cycle

European birds breed in summer, and Indian birds start in January and February. Indian chicks fledge before the monsoon arrives. Courtship begins in March in Europe, and the eggs follow in April and May. Both birds build a rough platform of sticks in a tree, usually near the trunk. Nests sit 2 to 30 metres up, and most are between 8 and 15 m. Cliff ledges and electricity pylons are used as well.

The nest is lined with paper, feathers, plastic and almost anything else the birds find. A pair often reuses a site, and sometimes takes over an old nest from another bird. Pairs may nest close to each other and beside heron or cormorant colonies. The clutch is 2 or 3 off-white eggs freckled with brown, and 1 to 5 have been recorded. Incubation runs 30 to 34 days, and the female does most of the sitting.

The male brings food while the female incubates and broods. Chicks feed on scraps at the bottom of the nest before they learn to tear flesh at 33 to 39 days. They stand at 17 to 19 days and flap their wings at 27 to 31 days. After 50 days they climb out onto branches beside the nest. The brood stays in the nest for 42 to 56 days and depends on the parents for weeks longer. Siblings fight, and the weaker chick is often killed, though parents will favour a small chick with food.

Predators and threats

A full-grown black kite has almost no natural predator. The Eurasian eagle-owl is the exception and kills kites of any age. In the Italian Alps, eagle-owls nesting within a few kilometres cut kite breeding success sharply. Other black kites are a danger too, because they rob nests of eggs and chicks. The birds carry flatworm parasites picked up from the fish they eat.

Most deaths now come from people rather than predators. The birds perch on power lines and are electrocuted in numbers. Swooping for roadkill puts them in front of vehicles. Mass poisonings have followed the eating of poisoned voles on farmland. They are a serious birdstrike hazard at some airports, because of their size and their habit of soaring. Japanese black-eared kites store about 70 per cent of the mercury they swallow in their feathers.

Population and conservation

The IUCN lists the black kite as Least Concern. The range is enormous and the total may reach 6.7 million birds. That makes it the most numerous bird in the hawk family. iNaturalist alone carries more than 127471 observations of the species. The bird has been recorded in 177 countries on GBIF.

The picture is uneven under that large total. European populations are small, and the South Asian population is very large. Some local groups have crashed and others have swung up and down. Water pollution, farm pesticides, shooting and poisoned carcasses drive the local falls. Numbers in Taiwan dropped through the twentieth century and left a mixed population behind.

Cities appear to have been good to the species, unlike almost every other raptor. Rubbish tips, slaughter waste and rats support very high densities. That closeness probably raises the toll from wires, traffic and poison. Birds reach breeding age at 2 to 3 years old. A wild bird can live 24 years, and one Australian stray in New Zealand is about 21.

Relationship with humans

Few wild raptors appear to live as close to people as this one. It nests in city trees, feeds at tips and follows fishing boats and abattoirs. It clears carrion and roadkill, which probably slows the spread of disease. It takes rats and mice in places where those animals damage stored food. Animal Diversity Web records no harmful effect of the species on people.

The exception is the food snatch. In parts of India people toss meat up for the kites, and the birds dive to catch it. Feeding has worn away their fear, and they now take food straight from a hand. Bystanders have been badly cut by the talons during these dives. Kites also dive at anyone who climbs to a nest, and they seem to remember the individual.

In culture and myth

In Aboriginal Australian tradition, birds are said to carry fire and spread it across country. Field reports from northern Australia describe black kites doing exactly that with burning sticks. The name firehawk covers the black kite and two other raptors that behave the same way. The English name fire kite probably comes from the same habit of working a fire front. The bird appears to sit at the meeting point of a story and a measurement.

In British military tradition, servicemen in hot countries named the bird the shite-hawk. The word passed into general slang and probably lost its link with the bird. In English naming tradition, the word kite began as an imitation of a raptor's call. In Indian tradition, the bird was long called the pariah kite, after a term for low caste. That name has now been dropped in favour of small Indian kite.