Aquila rapaxtawny eagle

Geographic Range

Tawny eagles occur from Romania east to southern Russia and Mongolia, and south through India and much of Africa. (Campbell, 1983)

Habitat

Tawny eagles favor arid climates but occupy a wide range of habitats including deserts, steppes, open savannah, open grassland, mountainous regions, and cultivated steppes. The tend to avoid dense forests. (Brown, et al., 1982; Burton, 1983; Campbell, 1983; Channing, 2006)

  • Range elevation
    600 to 4500 m
    1968.50 to 14763.78 ft

Physical Description

Aquila rapax plumage varies from very dark brown to light brown shades with blackish flight feathers and tail, light colored stripes or bars on the wings, and a pale lower back. Tawny eagles with darker shades of brown generally have tawny coloration on the body, distinguishing them from similar species of eagles, which lack any tawny coloration. The eyes are brown and the beak is yellow with a dark tip. Females are typically larger than males, otherwise the sexes are similar. Immature tawny eagles are paler and more streaked than are adults, sometimes "blonde" (white). Tawny eagles were thought to be synonymous with steppe eagles (Aquila nipalensis). Steppe eagles are larger than tawny eagles (up to twice the size in weight) and are darker in color. (Brown, 1977; Brown, et al., 1982; Campbell, 1983; Clancey, 1964; Maclean, 1988)

  • Sexual Dimorphism
  • female larger
  • Range mass
    1950 to 2500 g
    68.72 to 88.11 oz
  • Range length
    65 to 72 cm
    25.59 to 28.35 in
  • Range wingspan
    1.72 to 1.85 m
    5.64 to 6.07 ft

Reproduction

Tawny eagles are monogamous, pairing for life. Behavior prior to and during mating varies for this species, but usually involves undulating displays made by the male followed by mutual soaring displays. Epigamic display, display that occurs during breeding, may involve high circling, alone or in pairs, over the nesting site. The male may perform a series of "pot hooks" which involves a series of gradual dives and swoops, with little to no wing flapping. The female may turn over and present her claws in response to the male swooping over her. Males and females may lock claws in flight. Actual mating usually occurs at or near the nesting site. (Brown and Amadon, 1968; Brown, 1977; Brown, et al., 1982; Maclean, 1988)

Tawny eagles breed once yearly. Breeding season varies by geographic location, but typically occurs from April to July. Males and females both build the nest. Males collect nest material, while females assemble the nest. Nests are usually in trees or telephone poles and are occupied for one to three years before they are abandoned. Female tawny eagles lay one to three eggs at three day intervals and incubate them for approximately 45 days. Although males primarily feed offspring while they are young, both parents bring food during fledging, which occurs at approximately 76 to 85 days old. Tawny eagles begin to fly around ten weeks, but chicks remain in the nest for approximately 5 more weeks after their first flight and remain reliant on their parents for food during this period. After that, the young become independent. Siblings are aggressive towards one another, many times resulting in the death of the younger hatchling, usually within the first few days of hatching. (Brown, et al., 1982; Burton, 1983; Campbell, 1983; Knystautas, 1993; Maclean, 1988)

  • Breeding interval
    Tawny eagles breed once yearly.
  • Breeding season
    The breeding season of tawny eagles is generally from April to July.
  • Range eggs per season
    1 to 3
  • Range time to hatching
    39 to 45 days
  • Range fledging age
    76 to 85 days
  • Average fledging age
    84 days
  • Average time to independence
    120 days
  • Range age at sexual or reproductive maturity (female)
    3 to 4 years
  • Range age at sexual or reproductive maturity (male)
    3 to 4 years

Female tawny eagles generally incubate the eggs, occasionally assisted by males. For the first ten days females remain by the nest, brooding day and night, and males may also brood or shade the chicks from the sun. After 7 days females leave the chicks for extended periods, but stay near the nest to protect them. They continue to perch near the nest for approximately forty days. At fifty days, neither males nor females are near the nest during the day. Males brings most of the food for the chicks, but may be assisted by females after fifty days. Chicks make their first flight around 84 days old and may remain in the nest for up to forty days after the first flight. However, some young remain with the parents until the following breeding season. (Brown, et al., 1982; Burton, 1983; Campbell, 1983)

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

Lifespan/Longevity

The lifespan of adult eagles is difficult to determine in the wild. The oldest golden eagles, also in the genus Aquila, are recorded to have lived for sixty years. The average lifespan of golden eagles is 18 years, and they live approximately 40 to 45 years in captivity. The lifespan of tawny eagles may be similar to these values. In East Africa it is estimated that the lifespan of tawny eagles is 16 years on average, assuming that there is a 75% mortality rate before sexual maturity. Eagles live much longer in captivity, rarely reaching the same ages in the wild due to the high mortality rate within the first twelve months of life. (Brown, 1977; Brown, et al., 1982; Love, 1989; "Sedgwick County Zoo", 2006)

  • Range lifespan
    Status: wild
    40.3 (high) years
  • Average lifespan
    Status: wild
    16 years
  • Typical lifespan
    Status: captivity
    40 to 45 years

Behavior

Tawny eagles are gregarious outside of the breeding season. Groups of at least twenty are commonly observed, especially when large amounts of food are locally available (such as swarms of locusts and large populations of rats). Tawny eagles spend time near water where they can drink freely. Tawny eagles normally fly only when thermals can assist in soaring, and usually perch in trees during the day, especially in heavy rain. Tawny eagles, like most other eagles, are diurnal. Some populations of tawny eagles are migratory but many are not. (Brown, et al., 1982; Campbell, 1983; Channing, 2006)

  • Range territory size
    25 to 100 km^2
  • Average territory size
    35-55 km^2

Home Range

Tawny eagles tend to occupy the same territory for many years, sometimes even decades, in pairs. Territories are usually fairly far apart (20 km^2) to avoid food stealing by neighboring tawny eagles. Territories may range from 25 to 100 km^2 in area, most are 35-55 km^2. (Brown, et al., 1982)

Communication and Perception

Tawny eagles are generally fairly silent, except when aggravated or displaying. Their call can be described as a sharp kwok kwok. Occasionally tawny eagles will call during acts of piracy. Females may call from the nest, soliciting food. In general, vision is acute among eagles, and is likely to be their most important sense. They are able to see prey clearly at distances and up close. Their acute vision may also help in establishing territories. Hearing is also an important sense for tawny eagles, as it helps them locate prey when they are hunting. (Brown, 1977; Brown, et al., 1982; Campbell, 1983)

Food Habits

Tawny eagles are generalist carnivores, they will eat insects, carrion, and small animals such as rodents. They are the only type of eagle that scavenge from humans regularly. Tawny eagles are also well known for robbing prey from other raptors, even birds much larger than they are. (Brown, 1977; Campbell, 1983)

  • Primary Diet
  • carnivore
    • eats terrestrial vertebrates
  • Animal Foods
  • mammals
  • carrion
  • insects

Predation

Nest predation by crows occurs more regularly in the nests of tawny eagles than in other species, possibly due to the openness of the nest site. There is very little other information on other predators or behaviors to prevent predation in tawny eagles. Tawny eagles are large birds of prey once they reach adulthood, they are probably do not have many predators. (Brown, et al., 1982)

  • Known Predators

Ecosystem Roles

Tawny eagles are primary predators. They are also piratical and opportunistic. They will steal prey from other animals as well as scavenge already dead prey. (Brown, 1977; Campbell, 1983)

Economic Importance for Humans: Positive

Tawny eagles are important members of the ecosystems in which they live.

Economic Importance for Humans: Negative

Tawny eagles are piratical and steal and scavenge food from other animals and humans. They may occasionally take domestic livestock, although not often enough to have a significant negative impact on humans. (Brown and Amadon, 1968)

Conservation Status

The current IUCN Red List status of this species is "lower risk/least concern."

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Joslyn Westphal (author), Kalamazoo College, Ann Fraser (editor, instructor), Kalamazoo College.

Glossary

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.

arboreal

Referring to an animal that lives in trees; tree-climbing.

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.

carnivore

an animal that mainly eats meat

carrion

flesh of dead animals.

chemical

uses smells or other chemicals to communicate

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

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.

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).

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.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

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

oviparous

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

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 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.

visual

uses sight to communicate

References

Sedgewick County Zoo. 2006. "Sedgwick County Zoo" (On-line). Golden Eagle. Accessed November 09, 2006 at http://www.scz.org/animals/e/golden.html.

Brown, L., E. Urban, K. Newman. 1982. The Birds of Africa Vol. 1. London: Academic Press Inc.

Brown, L. 1977. Eagles of the World. New York, NY: Universe Books.

Brown, L., D. Amadon. 1968. Eagles, Hawks, and Falcons of the World. New York, NY: McGraw-Hill Book Company.

Burton, P. 1983. Vanishing Eagles. New York, NY: Dodd, Mead & Company, Inc.

Campbell, B. 1983. The Dictionary of Birds in Color. New York, NY: Exeter Books.

Channing, K. 2006. "The Hawk Conservancy Trust" (On-line). Accessed October 15, 2006 at http://www.hawk-conservancy.org/priors/frodo.shtml.

Clancey, P. 1964. Birds of Natal and Zululand. London: Oliver and Boyd Ltd.

Knystautas, A. 1993. Birds of Russia. London: Harper Collins Publishers.

Love, J. 1989. Eagles. London: Whittet Books Ltd.

Maclean, G. 1988. Robert's Birds of Southern Africa. London: New Holland Publishers Ltd.