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Milvus migransblack kite

By Nathan Reich and Amanda Sorenson

Geographic Range

Black kites (Milvus migrans) occur in tropical portions of Australasia, Eurasia, and Africa. However, they are lacking in the Indonesian Archipelago, specifically in areas between the Wallace line and the mainland of Southeast Asia. Black kites also occur in temperate areas, including Palearctic, Oriental, Ethiopian, and Australian regions. However, year-round, they reside mainly in the southern-most areas of tropical Oriental and Ethiopian regions. Their abundance in these areas has been associated with the abundance of resources. There are no known regions in which this species has been introduced.

Their Palearctic range, spanning from the west coast of Central Europe to the east coast of Asia, is occupied only during early summer (late March to early May) and is mainly for breeding. The Australian region is used only during winters (December through February). Black kites migrate depending on the availability of roosting sites and resources. (Ferguson-Lees and Christie, 2001; Mebs and Schmidt, 2006; Sibylle, 2010)

Habitat

Black kites inhabit a broad range of habitats. Most are found in open areas where there is close access to water bodies such as rivers, ponds, or lakes. Black kites are commonly found along river edges, which provide necessary resources such as fresh water and fish. Wetlands are another habitat that attracts black kites. Black kites also occur in woodlands, open savannas, and sometimes even in large cities. It has been suggested that they reside in African and Asian cities because there is high prey abundance, such as roadkill or rats.

Most black kites migrate to Africa during the winter, settling near the southern Sahara region. Black kites are rarely seen in natural desert habitats or high elevation mountainous areas. In addition, although black kites are attracted to various woodland habitats, they rarely inhabit dense forests.

Black kite nests tend to be located 8 to 15 m above ground, in forests with close proximity to water or in areas with little tree cover. Black kites prefer mid-canopy parts of trees, but have been seen as high as 30 m. Occasionally, black kites nests will be located near nests of the closely related red kite (Milvus milvus). (Ferguson-Lees and Christie, 2001; Jais, 2009; Kilkenney-Blake, 2003; Mebs and Schmidt, 2006)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • coastal

Physical Description

Black kites are medium-sized raptors, weighing 560 g on average. Body length ranges from 47 to 60 cm, with an average wingspan of 140 to 150 cm. Their dorsal coloration is mostly brown, which fades to a darker brown towards the tips of the wings and tail. The ventral color is mostly brown, but with a lighter brown to nearly rust color markings dispersed throughout. These markings are especially evident along the ventral body surface. The head of black kites is lighter in color (typically a faint brown or grey).

Black kites have small, bead-like dark brown eyes and a large black, hook-shaped beak for tearing flesh and consuming their prey. The outer edge of their wings appears to be "fingered" (a space between each feather gives the appearance of fingers). In addition, this species is recognized for its yellow cere, the skin located on the top of the beak near the nostrils. Black kites are often called "fork-tailed kites" because of the distinct shape of their tails. Their tail feathers are split, forming a v-shape; hence the name “fork-tailed”. Tail coloration is mostly brown, with darker brown striped feathers within. Black kites have long black talons and pale yellow legs. Their sharp talons are very effective for catching and holding prey. Black kites exhibit slight sexual dimorphism in that females have a slightly larger body size than males, through they feature similar coloration. Juveniles are generally lighter in color and have shorter forked tails than adult black kites.

The genus Milvus includes red kites (Milvus milvus), yellow-billed kites (Milvus aegyptius), and Cape Verde kites (Milvus milvus fasciicauda). Black kites often are confused with closely related yellow-billed kites, because of their similar appearance. The main difference between these two species is that yellow-billed kites have yellow bills, whereas black kites have black bills. Red kites are also similar in appearance to black kites because of their yellow legs and brown coloring. (Ferguson-Lees and Christie, 2001; Kilkenney-Blake, 2003; Meyer and Francl, 1995; Vang and Dabrowka, 2011)

  • Sexual Dimorphism
  • sexes alike
  • female larger
  • Average mass
    540 g
    19.03 oz
  • Range length
    47 to 60 cm
    18.50 to 23.62 in
  • Average length
    55 cm
    21.65 in
  • Average wingspan
    140 to 150 cm
    in

Reproduction

Black kites are believed to be monogamous, having a single mate at a time and may even pair for life, although there has been some debate. Black kites have a ritualized aerial courtship, which consists of extremely loud calls to one another. In addition, they perform a dangerous display known as grappling, where they lock their feet together in mid-air and begin to spiral towards the ground. Ritual courtship behaviors typically begin in March. (Avery, 2002; Ferguson-Lees and Christie, 2001; Jais, 2009; Kiff, 1999; Vang and Dabrowka, 2011)

Black kites breed seasonally between the months of March and August, though this period varies slightly with geographic location. Nest construction follows pair-formation in March, and egg laying occurs between April and May. Black kites reach maturity between 2 and 3 years of age. Nests are located at heights of 2 to 30 m and tend to be built in open forest. Black kites position their nest near the trunk of the tree. Nests also have been found on cliff edges and even on electricity pylons. Occasionally, black kites will build their nests relatively close to other black kite pairs. Nests have also been known to be placed near other species of birds, including grey heron (Ardea cinerea) and cormorant (Phalacrocorax carbo) rookeries. New nests usually are built each year, but sometimes they will occupy old nests built or abandoned by other black kites or other species. Nests consist of mainly bulky sticks, arranged in layers, many different kinds of soft materials, such as paper, feathers, plastic, feces or almost any other materials they can find.

Black kites on average lay 2 to 3 eggs each year. Occasionally they will lay as few as one or as many as five. Eggs are typically off-white in color, decorated with brown, freckled spots. Incubation averages 32 days. After hatching, the young stay in the nest with the parents for 42 to 56 days. On average, fledged young are protected and cared for by both parents for an additional 15 to 56 days, or until the young are self-reliant. (Avery, 2002; Ferguson-Lees and Christie, 2001; Jais, 2009; Kiff, 1999; Mebs and Schmidt, 2006; Vang and Dabrowka, 2011)

  • Breeding interval
    Black Kites breed once yearly
  • Breeding season
    The breeding season occurs from March until August
  • Range eggs per season
    1 to 5
  • Average eggs per season
    2 to 3
  • Range time to hatching
    28 to 32 days
  • Average time to hatching
    32 days
  • Range fledging age
    42 to 56 days
  • Range time to independence
    15 to 56 days
  • Range age at sexual or reproductive maturity (female)
    2 to 3 years
  • Range age at sexual or reproductive maturity (male)
    2 to 3 years

Both the male and female assist in the nest building process. Black kites are very territorial and are constantly alert for potential predators that might harm their young or themselves. Female black kites invest their time in incubating eggs, while males are responsible for providing food to the female and their offspring. Once the fledging stage begins, both parents are responsible for care of the young, which can continue for several months. (Jais, 2009; Koga and Shiraishi, 1994; Vang and Dabrowka, 2011)

  • Parental Investment
  • altricial
  • male parental care
  • female parental care
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male
      • female

Lifespan/Longevity

In the wild, black kites have been recorded to live up to 24 years. Expected lifespan of black kites averages 22 years. There are no known captive records, but their closest relative, Milvus milvus, has a known lifespan in captivity of up to 26 years. (Avery, 2002; Meyer and Francl, 1995; Richards, 1998)

  • Range lifespan
    Status: wild
    24 (high) years
  • Average lifespan
    Status: wild
    22 years

Behavior

Black kites typically live in social groups. During the breeding season, however, they can be solitary or live in smaller groups. Sibling dominance is determined by hatching order of the birds and the mass of the eggs, because larger eggs usually result in larger birds. This hierarchy also develops because birds that hatch first have an advantage by learning earlier then birds that hatch later.

Most populations of black kites migrate seasonally. Where they migrate usually is dependent on the specific geographic range of the kite. In general, populations that breed in northern regions will migrate south to overwinter. Populations that breed in more tropical regions will often remain in the same area year-round if resources remain abundant. (Ferguson-Lees and Christie, 2001; Kiff, 1999; Mebs and Schmidt, 2006; Vinuela, 1996)

Home Range

When M. migrans is not migrating, its home range is close to its roosting site. Exact territory size for this species is currently unknown. (Bird, et al., 2009; Ferguson-Lees and Christie, 2001; Kilkenney-Blake, 2003; Meyer and Francl, 1995)

Communication and Perception

Black kites have well developed intraspecific communication, vocalizing very loudly and often with other black kites. Their screech starts out as a long drawn "kleee-errr" sound, then transitions into a sharper "keee-keee-keee" call. They communicate using high pitches for a variety of different situations, such as breeding, at roosting sites, or even during group hunting. Black kites use these calls during pre- and post-breeding to communicate with mates. The calls of black kites are similar to those of red kites (Milvus milvus). Black kites even appear to be able to communicate with red kites in captivity. Sight is well-developed, allowing them to see prey at great distances.

During the breeding season, pairs will occasionally engage in physical displays of talon locking where the two birds grasp talons and spiral to the ground from great heights.

Like most birds, black kites perceive their environments through visual, auditory, tactile and chemical stimuli. (Ferguson-Lees and Christie, 2001; Sibylle, 2010)

Food Habits

Black kites have broad, carnivorous diets and feed on many different animal species. They are considered insectivores, piscivores, and scavengers. Black kites will hunt for food, but more often act as scavengers. They will steal eggs from other kites for food and scavenge dead carcasses left behind from other animals. Black kites also are known to hover over fires to catch insects. Their diet also includes a variety of fish, reptiles, amphibians and other small mammals and birds.

Black kites will catch and eat their prey by using their sharp talons to dig into and pull apart the prey both in aerial and ground attacks. They also often rely on the thermal air currents to aid in their attempt to locate food. (Ferguson-Lees and Christie, 2001; Hollands, 2003; Jais, 2009; Mebs and Schmidt, 2006; Sibylle, 2010; Vang and Dabrowka, 2011; Veiga and Hiraldo, 1990)

  • Animal Foods
  • birds
  • mammals
  • amphibians
  • reptiles
  • fish
  • eggs
  • carrion
  • insects

Predation

Black kites are natural predators of each other; they tend to steal eggs from other kites' nests. Another predominant predator of the black kites is humans, though most of the time it is not intentional. This usually occurs when humans encroach on black kite habitats or when black kites go to densely human populated areas in order to search for food. When either of these happens, there is the chance for the birds to have accidents with vehicles, or eat things that might be poisonous to them.

The overall brown coloring of black kites may help in blending into trees to avoid predators. Their loud, high pitched screams also are likely to scare away potential predators. (Cooper, 1973; Ferguson-Lees and Christie, 2001; Veiga and Hiraldo, 1990)

  • Known Predators

Ecosystem Roles

Black kites play an essential role as efficient scavengers within their ecosystems. A variety of external parasites are found on black kites, as well as several species of endoparasitic trematodes such as Opisthorchis cheelis and some parasitic flatworms like Holostephanus metorchis. These are typically ingested during the consumption of fish. (Makund, 1939; Seo, et al., 2008)

Commensal/Parasitic Species
  • trematode (Opisthorchis cheelis)
  • parasitic flatworms (Holostephanus metorchis)

Economic Importance for Humans: Positive

Although there are no known benefits of black kites to humans, red kites, their closest known relative, consume many crop-destroying pests. In addition, they scavenge road-kill, which potentially may help to reduce the spread of disease. (Meyer and Francl, 1995; Richards, 1998)

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

There are no known adverse effects of Milvus migrans on humans.

Conservation Status

According to the International Union for Conservation of Nature and Natural Resources' (IUCN) Red List, Milvus migrans is given the conservation status of "Least Concern," showing no near possible threats to the species. This is due to the fact that the species covers many different areas and has such a large population within the areas. Though some populations are declining in numbers, the numbers are not significant to decrease the population as a whole. Causes of local population declines include water pollution, agricultural pesticides and associated runoff, hunting by humans, and carcass poisoning. (Bielby, 2010; Ferguson-Lees and Christie, 2001)

Contributors

Nathan Reich (author), Radford University, Amanda Sorenson (author), Radford University, Christine Small (editor), Radford University, Rachelle Sterling (editor), Special Projects.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

biodegradation

helps break down and decompose dead plants and/or animals

carnivore

an animal that mainly eats meat

carrion

flesh of dead animals.

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

estuarine

an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.

female parental care

parental care is carried out by females

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

male parental care

parental care is carried out by males

marsh

marshes are wetland areas often dominated by grasses and reeds.

migratory

makes seasonal movements between breeding and wintering grounds

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

scavenger

an animal that mainly eats dead animals

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

visual

uses sight to communicate

References

Avery, R. 2002. The International Wildlife Encyclopedia. Tarrytown, New York: Marshall Cavendish Corporation.

Bielby, J. 2010. "Milvus migrans" (On-line). IUCN Red List. Accessed April 04, 2011 at http://www.iucnredlist.org/apps/redlist/details/181381/0.

Bird, J., S. Butchart, J. Ekstrom, M. Harding. 2009. "Red kite (Milvus milvus)" (On-line). Bird Life International. Accessed May 05, 2011 at http://www.birdlife.org/datazone/speciesfactsheet.php?id=3353.

Bustamante, J., F. Hiraldo. 1990. Factors influencing family rupture and parent-offspring conflict in the black kite (Milvus migrans). IBIS, 132/1: 58-67.

Cooper, J. 1973. Post-mortem findings in east African birds of prey. Journal of Wildlife Diseases, 9: 368.

Cupper, J., L. Cupper. 1981. Hawks in Focus: A Study of Australia's Birds of Prey. Cornell University: Jaclin Enterprise.

Duchi, A., N. Agostini. 1994. Water-crossing behavior of black kites (Milvus migrans) during migration. Bird Behavior, 10/1-4: 45-48(4).

Ferguson-Lees, J., D. Christie. 2001. Raptors of the World. Great Britain: Christopher Helm.

Forero, M., J. Donazar, J. Blas, F. Hiraldo. 1999. Causes and consequences of territory change and breeding dispersal distance in the black kite. Ecology, 80/4: 1298-1310.

Forero, M., J. Donazar, F. Hiraldo. 2002. Causes and fitness consequences of natal dispersal in a population of black kites. Ecology, 83/3: 858-872.

Hiraldo, F., J. Veiga, M. Manez. 1990. Growth of nestling black kites (Milvus migrans): effects of hatching order, weather and season. Journal of Zoology, 222/2: 197-214.

Hollands, D. 2003. Eagles, Hawks and Falcons of Australia. Australia: Blooming Books.

Jais, M. 2009. "Black kite, Milvus migrans" (On-line). European Raptors: Biology and Conservation. Accessed February 17, 2011 at http://www.europeanraptors.org/raptors/black_kite.html.

Kiff, L. 1999. "Black kite Milvus migrans" (On-line). Global Raptor Information Network. Accessed March 20, 2011 at http://globalraptors.org/grin/SpeciesResults.asp?specID=8305.

Kilkenney-Blake, D. 2003. "Black kite (Milvus migrans)" (On-line). ARKive. Accessed February 16, 2011 at http://www.arkive.org/black-kite/milvus-migrans/#text=Habitat.

Koga, K., S. Shiraishi. 1994. Copulation behaviour of the black kite (Milvus migrans) in Nagasaki Peninsula. Bird Study, 41/1: 29-36.

Makund, B. 1939. Studies in Helminthology: Trematode parasites of birds. Proceedings of the Indian Academy of Science, 10/2: 111-200.

Mebs, T., D. Schmidt. 2006. Die Greifvögel Europas, Nordafrikas und Vorderasiens. Germany: Kosmos Verlag.

Meyer, B., K. Francl. 1995. "Animal Diversity Web" (On-line). Milvus milvus. Accessed March 20, 2011 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Milvus_milvus.html.

Richards, A. 1998. Birds of Prey: Hunters of the Sky. Philadelphia, Pennsylvania: Courage Books.

Seo, M., S. Guk, J. Chai, S. Sim, W. Sohn. 2008. Holostephanus metorchis (Digenea: Cyathocotylidae) from chicks experimentally infected with Metacercariae from a fish, Pseudorasbora parva, in the republic of Korea. The Korean Journal for Parasitology, 46(2): 83-86.

Sergio, F. 2003. Relationship between laying dates of black kites Milvus migrans and spring temperatures in Italy: Rapid response to climate change?. Journal of Avian Biology, 34/2: 144-149.

Sergio, F., A. Boto. 1999. Nest dispersion, diet and breeding success of Black kites (Milvus migrans) in the Italian Pre-Alps. The Raptor Research Foundation, 33/3: 207-217.

Sergio, F., P. Pedrini, L. Marchesi. 2003. Adaptive selection of foraging and nesting habitat by black kites (Milvus migrans) and its implications for conservation: a multi-scale approach. Biological Conservation, 112/3: 351-362.

Sibylle, J. 2010. "Black kites" (On-line). Avian Web. Accessed February 16, 2011 at http://www.avianweb.com/blackkites.html.

Vang, K., W. Dabrowka. 2011. "Black kite" (On-line). Birds in Backyards. Accessed February 15, 2011 at http://birdsinbackyards.net/species/Milvus-migrans.

Veiga, J., F. Hiraldo. 1990. Food habits and the survival and growth of nestlings in two sympatric kites (Milvus milvus and Milvus migrans). Holarctic Ecology, 13/1: 62-71.

Vinuela, J. 1996. Establishment of mass hierarchies in broods of the black kite. The Condor, 98/1: 93-99.

Vinuela, J. 1999. Sibling aggression, hatching asynchrony, and nestling mortality in the black kite (Milvus migrans). Behavioral Ecology and Sociobiology, 45/1: 33-45.

Vinuela, J., J. Veiga. 1992. Importance of rabbits in the diet and reproductive success of black kites in southwestern Spain. Ornis Scandinavica, 23/2: 132-138.

Viñuela, J. 2000. Opposing selective pressures on hatching asynchrony: egg viability, brood reduction, and nestling growth. Behavioral Ecology and Sociobiology, 48/5: 333-343.

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