Corvus coraxcommon raven

Geographic Range

Common ravens are one of the most widespread, naturally occurring birds worldwide. They are found in northern Europe, the British Isles, Greenland (mainly coastal areas), Iceland, northern Scandinavia, east through central Asia to the Pacific Ocean and south to the Himalayas and northwestern India, Iranian region and near east, northwestern Africa and the Canary Islands, and North and Central America as far south as Nicaragua. (Boarman and Heinrich, 1999)

Habitat

Common ravens prefer open landscapes, such as treeless tundra, seacoasts, open riverbanks, rocky cliffs, mountain forests, plains, deserts, and scrubby woodlands. However, these ravens can be found in most types of habitats except for rainforests. Common ravens in North America tend to be found in wild areas, whereas their cousins, common crows tend to be found in areas more affected by human habitation. In some parts of their range they have become quite habituated to humans and can be found in urban areas. (Boarman and Heinrich, 1999)

Common ravens generally roost on cliff ledges or in large trees but have also established nests on power-lines, in urban areas, and on billboards, to name only a few. (Boarman and Heinrich, 1999)

Physical Description

Common ravens are large, black birds with a wedge-shaped tail. They have a well-developed ruff of feathers on the throat, which are called 'hackles' and are used often social communication. These are the largest passerines. Adults reach up to 69 cm in length and from 689 to 1625 grams in weight. They are generally distinguished from other Corvus species by their large size, more wedge-shaped tail, robust bill, a tendency to soar and glide, and their frequent, harsh, croaking calls. The sexes are generally alike, although females may be smaller. (Boarman and Heinrich, 1999)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    689 to 1625 g
    24.28 to 57.27 oz
  • Range length
    69 (high) cm
    27.17 (high) in
  • Average basal metabolic rate
    5.5656 W
    AnAge

Reproduction

There is little information on when or how pair formation occurs. Displays occur between individuals throughout the year, some of which may be courtship. These displays are most intense in the fall and winter. There is evidence that pairs stay together throughout the year but no concrete evidence that mating occurrs for life. Females invite copulation by crouching slightly or opening, extending, or drooping their wings and shaking or quivering a slightly raised tail. (Boarman and Heinrich, 1999)

Breeding and egg laying occurs between mid-February and late May, though most clutches are started in March or April. Breeding season varies by region and by the length of the winter. Usually 3 to 7 eggs are laid per nest and incubated for 20 to 25 days. Nests are made mostly of sticks, are asymmetrical, and measure 40 to 153 cm diameter by 20 to 61 cm high at the base and 22 to 40 cm diameter by 13 to 15 cm deep in the cup. Young leave the nest between 5 and 7 weeks of age. They may then leave the area, and their family, within a week or may remain with the parents for a more extended period of time. Sexual maturity is reached at about 3 years of age.

  • Breeding interval
    Common ravens breed once yearly.
  • Breeding season
    Breeding occurs in lmid-February through May.
  • Range eggs per season
    3 to 7
  • Average eggs per season
    5
    AnAge
  • Range time to hatching
    20 to 25 days
  • Range time to independence
    5 to 7 weeks
  • Average age at sexual or reproductive maturity (female)
    3 years
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    1095 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    3 years
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    1095 days
    AnAge

Females exclusively incubate the eggs but both parents care for the young once they have hatched.

  • Parental Investment
  • no parental involvement
  • altricial
  • pre-fertilization
    • protecting
      • female
  • pre-hatching/birth
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • post-independence association with parents
  • extended period of juvenile learning

Lifespan/Longevity

A wild raven was recorded living for 13 years and 4 months. Captive birds may live much longer, one captive individual was recorded to have lived 80 years and captives at the Tower of London in England live for 44 years or more. Probably most common ravens die during their first few years of life. (Boarman and Heinrich, 1999)

  • Range lifespan
    Status: wild
    13 (high) years
  • Range lifespan
    Status: captivity
    >44 (high) years
  • Typical lifespan
    Status: captivity
    44 (high) years
  • Average lifespan
    Status: wild
    206 months
    Bird Banding Laboratory

Behavior

Common ravens are known for their intelligence and complex social dynamics. They seem capable of learning innovative solutions to newly encountered problems. Common ravens often forage in larger groups in areas where resources are concentrated, and non-breeding individuals may occupy communal roosts, but most commonly ravens occur alone or in pairs. Breeding pairs establish nesting territories, which vary in size with the density of resources in the area. Migration has not been recorded in common ravens, but populations at the edges of their range may make shorter seasonal movements to avoid extreme weather. (Boarman and Heinrich, 1999)

Common ravens walk on the ground or fly. They may also glide and soar, which they do more often than American crows. (Boarman and Heinrich, 1999)

  • Range territory size
    5.1 to 40.5 km^2

Communication and Perception

Common ravens are very vocal animals, with a diverse suite of calls and non-vocal sounds for different purposes and social contexts. From 15 to 33 categories of vocalizations have been described in this species. There are alarm calls, comfort sounds, chase calls, and calls designed for advertising territories. Common ravens may be able to mimic sounds of other animals but this has not been unambiguously documented. It is also possible that they are simply capable of a huge diversity of sounds and innovation enough to create calls that sound like those of others. Young birds engage in vocal play, in which they seemingly go through their entire repertoire of sounds, pitches, and volumes for minutes or hours at a time. Non vocal sounds include wing whistles and bill snapping. (Boarman and Heinrich, 1999)

Common ravens also communicate with physical displays of either threat or appeasement to subordinate and dominant ravens. Territorial pairs chase intruders for several kilometers and may engage in aerial fights. Tactile cues via allopreening are also used. Common ravens perceive their environment through vision, some chemical cues, tactile, and auditory stimuli. (Boarman and Heinrich, 1999)

Food Habits

Common ravens are mainly scavengers. They eat a wide array of animal foods, including arthropods, amphibians, small mammals, birds, reptiles, and carrion. They are attracted to carrion and eat also the insects that feed on carrion (chiefly on maggots and beetles). They are also known to eat the afterbirth of ewes and other large mammals. Vegetable foods include grains, acorns, fruits, and buds. Stomach analyses show that the diet is made up primarily of mammalian flesh, followed by insects and birds. Common ravens take their food from the ground and will store foods of all kinds, including nuts, bones, eggs, and meat. Young ravens begin to experiment with caching edible and non-edible objects soon after leaving the nest. (Boarman and Heinrich, 1999)

  • Animal Foods
  • birds
  • mammals
  • amphibians
  • reptiles
  • eggs
  • carrion
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • seeds, grains, and nuts
  • fruit

Predation

Common ravens are rarely observed being preyed on, even as eggs or young in the nest. Predators on nestlings may include large hawks and eagles, other ravens, owls, and martens. Golden eagles, great horned owls, and coyotes have been observed attacking nests and fledglings. Adults are usually successful at defending their young and will vigorously chase predators away. Adults are wary of approaching novel kinds of carrion and new situations and will often only approach after the presence of blue jays and American crows makes it clear that no danger is near. (Boarman and Heinrich, 1999)

Ecosystem Roles

Common ravens consume carrion, thereby helping in nutrient cycling. They are also important predators of arthropods, mammals, and birds in the ecosystems in which they live.

Economic Importance for Humans: Positive

Common ravens eat carrion, which helps by removing dead animals that may harbor diseases.

Economic Importance for Humans: Negative

Common ravens sometimes eat crops such as grains, nuts, and fruits, and have been accused of killing or maiming small livestock. They may also negatively affect conservation efforts aimed at desert tortoises, sandhill cranes, and California condors. (Boarman and Heinrich, 1999)

  • Negative Impacts
  • crop pest

Conservation Status

Common ravens have been persecuted by humans for allegedly preying on lambs and crops. They are often shot, poisoned, or captured in traps. Ravens have been killed on a local scale in order to protect other endangered species programs, such as the programs to protect desert tortoises and sandhill cranes, where ravens were implicated in predation on those animals. In some parts of their range, common ravens have been extirpated but some populations are becoming re-established. (Boarman and Heinrich, 1999)

Other Comments

Common ravens are very important in native cultures throughout their range. Raven is a common and important mythic creature in western Native American traditions. (Boarman and Heinrich, 1999)

Contributors

Tanya Dewey (author, editor), Animal Diversity Web.

Rachel Berg (author), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

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

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.

carnivore

an animal that mainly eats meat

carrion

flesh of dead animals.

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

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.

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.

forest

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

holarctic

a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.

World Map

Found in northern North America and northern Europe or Asia.

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).

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.

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.

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

solitary

lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

tactile

uses touch to communicate

taiga

Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.

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.

tundra

A terrestrial biome with low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth. Soils usually subject to permafrost. Plant diversity is typically low and the growing season is short.

visual

uses sight to communicate

References

Chandler, Robbins, Bruun, Zim, Golden, A GUIDE TO BIRDS OF NORTH AMERICA, Golden & Press, New York, 1966. (pgs 212-213)

Goodwin, CROWS OF THE WORLD, 2nd Edition, British Museum, 1986. (pgs. 124-130)

Terres, John K, THE AUDOBON SOCIETY ENCYCLOPEDIA OF NORTH AMERICAN BIRDS,

Boarman, W., B. Heinrich. 1999. Corvus corax: Common Raven. The Birds of North America, 476: 1-32.