Crows and jays

(Corvidae)

Class Aves

Order Passeriformes

Suborder Passeri (Oscines)

Family Corvidae

Thumbnail description
Medium to large-sized birds with large heads and stout, usually slightly hooked beaks, scaly legs, and powerful feet

Size
7.4–26.9 in (19–69 cm); 1.47 oz–3.66 lb (41.6 g–1.56 kg)

Number of genera, species
26 genera; 123 species

Habitat
Widespread family occupying most vegetated land habitats

Conservation status
Critically Endangered: 1 species; Endangered: 4 species; Vulnerable: 8 species; Near Threatened: 11 species

Distribution
All continents except Antarctica; introduced rook (Corvus frugilegus) in New Zealand

Evolution and systematics

The earliest fossil corvid, a jay-like "crow" was found in France and dates to the middle Miocene period (about 17 million years ago). The large number of species endemic to eastern Asia (36) and the New World (29) however, suggest that the family may have originated in the Far East, and taken alternative routes a very long time ago.

The ancestors of New World jays spread to the Americas, but no other corvids besides jays are found in South America. Marzluff and Balda conclude that the other genera were relatively recent arrivals in North America—the Bering land bridge that formed between Asia and North America allowed the Old World genera Corvus, Perisoreus, Pica, and Nucifraga to cross continents. Scientists are unclear why so few corvid species occur in Africa. The two monotypic genera have features which suggest an ancient origin: most strikingly, the Stresemann's bush-crow (Zavattariornis stresemanni), found only in southwest Ethiopia, is shaped like a ground-jay, colored like a nutcracker, and builds a nest like a magpie. Madge speculates that this species may be a relict population of an ancient ancestor to a number of genera.

Taxonomically, the corvids, consisting of 26 genera and 123 species, have fitted historically within the family Corvidae. DNA reclassification work has not changed this essential grouping. Sibley and Ahlquist (1990) widen the family to include such taxa as quail-thrushes, whipbirds, cuckoo-shrikes, and birds of paradise within a much bigger Corvidae family, placing the corvids together in a Corvinae subfamily. They argue that the enlarged family originated in Australia; since only members of the Corvus genus now live in Australia, they would have been recent re-colonists of their ancestral home.

Physical characteristics

Although corvids show huge variation in size—the largest is more than three times longer than the smallest—a number of features are common to most members of the family. All but three species have their nostrils either partially or completely obscured by bristles or plumes. In the majority of species, the tip of the curved upper mandible overlaps the lower mandible slightly. Some genera show adaptive development of the beak; the long, decurved bills of Podoces ground jays and Pyrrhocorax choughs are used to probe into narrow holes for food. The feet are proportionately large and powerful, with strong, grasping toes, suited to holding large and awkward items of prey still; the tarsi are scaled at the front and smooth behind.

Corvid wings are generally rounded and rather short in woodland species. Forms that embark on long migrations, such as a number of Corvus species, have longer wings. Tails are generally long, exaggeratedly so in some genera. Both the piapiac (Ptilostomus afer), which is unique in having 10 rather than 12 tail feathers, and the Pica magpies probably use their long tails for maneuverability. In forest-dwelling treepies, the tail helps with balancing. However, elaborate tails such as that of the ratchet-tailed treepie (Temnurus temnurus) may also have a display function.

Typical crows of the Corvus genus all have predominantly glossy black plumage with a metallic sheen. Species that appear identical in shape, size, and plumage can be sympatric. Australia has five species that offer the birder what Madge calls "the ultimate challenge to his field skills." However, although congeners frequently associate to feed and may overlap or even "share" breeding territories, interspecific pair formation in the wild is unknown. Clearly, the problems of identification rest with humans.

Their black plumage offers corvids considerable advantages. Since this color absorbs solar energy most effectively and radiates less heat, corvids in cold surroundings are better able to regulate body temperature. Dark melanin-pigmented feathers are also tougher than light feathers. In addition, in species such as ravens that are highly sociable and, because of their size as adults, largely untroubled by predators, it is beneficial for them to wear conspicuous black plumage, displaying their presence to conspecifics, even from a distance.

Other genera show a broad and sometimes dazzling range of colorful plumage. Unlike most other passerines, the body plumage is relatively simple, lacking cryptic streaks. In a number of species, the wings and tails are strongly marked, serving both to conceal and reveal. The Eurasian jay (Garrulus glandarius) is hard to spot in forests because its white wing patch acts as a disruptive feature to aid concealment when the bird is at rest. Equally, its white rump alerts conspecifics, as it is revealed when the jay leaves its perch. Some species use wing and tail markings in courtship display or in hostile encounters; the yellow-billed magpie (Pica nuttalli) flashes its wing patch to warn off rivals. The New World jays reveal a variety of display crests and plumes, from the short, backward-facing crest of the blue jay (Cyanocitta cristata), through the nasal tuft of the azure jay (Cyanocorax caeruleus), to the aptly named plush-crested jay (Cyanocorax chrysops), and the extravagant parakeet-like crest of the white-throated magpie-jay (Calocitta formosa). The only Old World species with a significant crest or plume is the crested jay (Platylophus galericu-latus). Since this is thought to be a primitive jay, it seems likely that such display features were simply lost from other Old World species as they evolved.

Juvenal plumage is not generally significantly different to that of adults, although the feathers are softer and duller in color. However, it is common for there to be other physical differences, usually in the eye or bill color, that enable adult conspecifics to rule out juvenals as potential mates or rivals. The first year juvenal Torresian crow (Corvus orru), for example, has a brown iris that turns hazel in the second year and white in its third, adult year.

Distribution

In his classic work Crows of the World, Derek Goodwin notes that "the amount of adaptive radiation and consequent differentiation found within the Corvidae surpasses that within many Passerine families." With the exception of Antarctica and some remote archipelagos of the Pacific, there is at least one corvid species for most parts of Earth.

In south and Southeast Asia, where Corvids may have originated, arboreal species proliferate. These include the primitive monotype crested jay and black magpie (Platysmurus leucopterus) of the Malay Peninsula and Southeast Asian islands, as well as the "tropical" magpies. This group of 18 colorful species consists of the blue Urocissa and green Cissa magpies, Dendrocitta treepies, racket-tailed treepies Crypsirina, and ratchet-tailed treepies Temnurus. The Pica genus of pied magpies has three species, widely distributed throughout the Northern Hemisphere, but geographically distinct.

On the central Asian desert scrub and steppe, stretching from Iran and Turkmenistan in the west to Tibet and Mongolia in the east, live the Podoces and Pseudopodoces ground-jays. Higher altitudes are occupied by the alpine chough (Pyrrhocorax graculus). Both the alpine and the lower-altitude redbilled chough (Pyrrhocorax pyrrhocorax) range through central and southern Europe.

The mountainous, coniferous forests of the Old World contain the Nucifraga nutcrackers, a genus of three species. The six Garrulus and Perisoreus jays occupy a wider variety of forest habitats in the Old World, including deciduous, mixed, and coniferous woodland. The Clark's nutcracker (Nucifraga columbiana) and gray jay (Perisoreus canadensis) are the only members of these genera to colonize the forests of North America.

The New World jays (36 species) are unique to the Americas, found in most forest and scrub south of the Canadian boreal forest. They are all bluish in color, with the exception of the brown jay (Cyanocorax morio). The crested Cyanocitta genus is found in woodland, parks, and gardens throughout North America; the Steller's jay (Cyanocitta stelleri) replacing the blue jay in the west and south. The crestless Cyanocola genus of southern United States, Mexico, and Central America includes the three species of scrub-jay. The largest genus in the Americas, Cyanocorax, consists of 16 similar species, which range through the forests of Central and South America, with northeast Argentina their southernmost limit.

The mostly blackish Corvus genus is the biggest (48 species) and most wide ranging of all genera. It is the only genus found in Africa south of the Sahara, and the only one represented in Australia, where there are five species. The distribution of the most widespread Australian species, the Australian raven (Corvus coronoides) in the east, south, and southwest of Australia corresponds with that of sheep. The majority of island endemics belong in this genus. Most are in the islands of the Pacific and Southeast Asia. Oddly, although no corvids other than jays are found in South America, five Corvus species have colonized the West Indies.

Wide-ranging Corvus species include the northern raven (Corvus corax), which has colonized much open country of the Northern Hemisphere, and the pied crow (Corvus albus), which adapts well to human habitation and is Africa's most widespread corvid, found in the southern half of the continent. Coexistence with human settlement has enabled other crows to flourish. The American crow (Corvus brachyrhynchos) in North America and the carrion crow (Corvus corone) of Europe and Asia are found in both rural and urban areas. In the twenty-first century, the house crow (Corvus splendens) may prove to be the most successful colonist of all. The native Indian subcontinent population is flourishing, but the bird's readiness to board ships heading for other parts of the world has enabled it colonize and thrive in Malaysia, the Middle East, and Africa. In the South African city of Durban alone, the population reached 12,000 birds just 12 years after the first sighting.

Habitat

Corvids colonize an extraordinarily wide range of habitats. The extremes serve to illustrate the breadth and diversity— alpine choughs have been observed feeding in the Himalayas at 2,700 ft (822 m); the "desert" choughs live in the steppe deserts of central Asia.

Corvids evolved as arboreal species, and some genera have remained wholly dependent on forest habitat. Jays of the Cyanolyca genus of Central and South America carry out nearly all of their foraging in the canopy, rarely, if ever, descending to the ground. Genera that have evolved specialized feeding techniques are largely restricted to particular types of forest and, exceptionally, even particular types of tree. Some forms of spotted nutcracker (Nucifraga caryocatactes) have unusually slender bills for feeding on the seeds of the Arolla pine (Pinus cemra); the two species may have evolved in symbiosis. Other genera are omnivorous, but show a marked preference for certain foods. The Garrulus jays favor oak acorns and oakliving invertebrates: their range usually coincides with that of oaks (Quercus spp.).

Those genera which rely on trees only for nesting and roosting occupy a much wider variety of habitats. Magpies of the Pica genus and some Corvus species, such as the Eurasian rook (Corvus frugilegus), are able to feed diurnally in a range of open habitats, returning at night to their tree roosts. Some species, most notably the American, carrion, and house crow, have become well adapted to living in areas of dense human settlement. Studies in New York have shown that although urban American crows have smaller territories and nest at

higher densities than rural crows, nesting success is broadly similar.

An adaptation to nesting on cliffs and on the ground or low bushes has enabled a number of species to colonize open country. The five species of ground-jay are all terrestrial feeders, and the Pyrrhocorax choughs feed on invertebrates on grazed pasture. Most raven species nest both in trees and on cliff ledges.

Behavior

When the great naturalist Henry David Thoreau, wrote "if men had wings and bore black feathers, few of them would be wise enough to be crows," he spoke for many, often grudging, corvid admirers. In The Dictionary of Birds, published in 1985, this family is thought to "represent the furthest stage so far reached in avian evolution: much in their behavior suggests a highly developed mentality." The numerous behavioral studies carried out since this book was published only serve to confirm a high estimation of corvids. Their huge brains give them a brain to body ratio that is equal to that of dolphins and only slightly smaller than that of humans.

All Corvus species are, to a greater or lesser extent, gregarious. The degree of social interaction is dependent on factors that are often complex and open to wide interpretation, but they include season, age, family relationships, defense strategies, and time of day.

Flocking behavior has developed among corvids as a means of exploiting localized food sources, with inexperienced birds gaining from the knowledge of older birds, and the group formation acting to deter predators. Yet the bonding between flock members varies considerably between species. Rooks and western jackdaws (Corvus monedula) frequently form mixed feeding flocks, but the only cohesion between individuals in these flocks is between mated pairs; when the flock is

disturbed, the birds disperse randomly, except for paired individuals, which fly off together. Other species, particularly New World jays, show a range of affinities within flocks. Such cohesive flocks may be relatively small: Florida scrub-jays associate in parent-offspring flocks of no more than six birds. Gray-breasted jays (Aphelocoma ultramarina) live in year-round extended family flocks of six to 18 birds. In the case of the pinyon jay (Gymnorhinus cyanocephalus), the fall "flock" numbering several thousand individuals is actually subdivided into many small clans of related birds.

Gregarious habits can evolve as a reaction to being slightly "afraid." Captive corvids often show agitated behavior towards nightfall. Many of their wild, diurnal compatriots, especially nonbreeders, compensate by roosting communally. These gatherings can reach numbers of epic proportions. A Munich roost has attracted more than one million rooks, jackdaws, and carrion crows, while American crow roosts in Oklahoma and Kansas have been known to draw in around nine million birds. Studies of hooded crows (Corvus corone cornix) in Norway show that birds in roosts are able to gain information from others about good feeding sites.

All corvids appear to be territorial, although the extent to which they defend territory is very variable, even within species. At one extreme, the individual pairs among colonial nesting species such as rooks and yellow-billed magpies defend only the area that consists of just a few feet around their nest.

By comparison, a number of species occupy large home ranges, and judging by consistent nest spacing in species such as the northern raven and Eurasian magpie (Pica pica), the core nesting area is defended. The carrion crow is a particularly aggressive nest defender; its biggest nest predator is other carrion crows. Curiously, urban carrion crows are observed to have a territorial "roof," and conspecifics are able to fly above this roof without being challenged. A number of species, including the Eurasian magpie and Eurasian jay, engage in "spring gatherings," where groups of unpaired birds gather at the edge of a territory and apparently "test" the resident pair. If the established birds do not produce a suitably aggressive response, they risk being ousted.

American and northwestern crows (Corvus caurinus) take on "helpers." Among New World jays, where at least 12 species employ helpers, research on Florida scrub-jays (Aphelo-coma coerulescens) has shown that pairs with helpers raise twice as many young as those without. No Old World corvids have been shown to adopt this behavior.

Most corvids are sedentary. In far northern temperate zones, some species migrate, or make cold weather movements. Large-scale irruptions occur in species dependent on an individual food, in years when the food crop fails. The Clark's nutcracker (Nucifraga columbiana) irrupts from its conifer habitats to urban backyards, coasts, and even deserts.

For a family that has no song in the recognized sense of the word, corvids are nevertheless remarkably and famously vocal. The song, such as it is, consists of a softly intoned jumble of calls, interspersed with mimicked sounds. Broadly speaking, a corvid's calls can be identified as performing a particular function, whether they are contact, threat, feeding, or territorial calls. For example, the immediacy of a threat will determine the volume and frequency of an alarm call in an American crow.

Vocal mimicry is widespread and can be separated into two categories. Lanceolated jays (Garrulus lanceolatus) are among the few species which add the sounds of other species or inanimate objects to their vocal repertoire. Some species do not use mimicry in the wild, but will do so when tamed.

Feeding ecology and diet

In their foraging behavior, corvids are largely restricted to ground feeding and taking food from trees. Use of other feeding techniques, such as aerial feeding and fishing, are rare. Most corvids are omnivorous. Those in tropical zones tend to live on a year-round diet of invertebrates, fruit and berries, reptiles, amphibians, small birds and mammals, and carrion, as well as eggs and young during the breeding season. The range of food items taken by corvids in the Northern Hemisphere, however, is dictated by seasonality. Studies of the Eurasian magpie diet are typical of the Corvus genus. They show a preponderance of plant material in the winter and of animal food in summer. Birds in areas of human habitation regularly supplement their diet with food provided by humans.

Very few corvids have specialist diets. Those that do have evolved morphological and behavioral adaptations. The western scrub jay (Aphelocoma californica) and Steller's jay both have wide-ranging diets that include insects and other invertebrates, fruits, nuts, berries, as well as the eggs and young of small birds. The seeds of pinyon (Pinus edulis) and ponderosa pine (Pinus ponderosa) are an important food source for these species too, but not to the extent shown by the pinyon jay, which feeds almost exclusively on pine seeds. Its morphological adaptations include an expandable esophagus that can inflate to hold up to 50 seeds at one time; the scrub jay can manage just five.

Corvids are renown for their intelligence and adaptability in getting food. Examples of optimal foraging include the ability of northwestern crows to weigh whelks to select the biggest, and then to drop them on rocks from a height which experiments have shown is ideal for breaking open large whelk shells. The use of tools was captured on film in the David Attenborough series The Life of Birds, in which New Caledonian crows (Corvus moneduloides) were shown collecting, trimming, and using twigs to probe into the hollows of logs for invertebrate grubs.

The hiding of food for later consumption is a characteristic of corvids. It confers obvious benefits for species that have a sudden abundance of food and a need to eke out their supplies to cover leaner periods. Studies of spotted nutcrackers in Siberia show that these birds are completely dependent on cached pine seeds from the fall until May. Each individual hides about 100,000 seeds and needs to find about a quarter of these to survive. Research on Eurasian jays indicates that these birds memorize the position of trees and other landmark features, so that they are able to retrieve buried acorns successfully. Although gray jays of boreal forest are unable to find food buried on the forest floor during winter when the ground is covered in deep snow, they solve this problem by gluing insects and pieces of meat onto the bark of trees using their own saliva.

Birds in temperate zones clearly gain from storing food when faced with a glut, but widespread evidence from tropical species too suggests that most, and possibly all corvids, engage in this behavior. In India, rufous treepies (Dendrocitta vagabunda) have been observed hanging up pieces of meat in trees. Other largely arboreal species wedge acorns and other seeds in cracks of trees. Some ground-feeders occasionally hide their find under grass or among leaves, but the general tendency is to bury the food underground.

Nevertheless, food storing is a risky strategy, since there is always the possibility that the stored food may be found by a conspecific or other species. Observations have shown that northern ravens and Eurasian jays return to caches that they have stored in the presence of conspecifics, then rebury them when the observers are no longer present. Studies of Florida scrub-jays demonstrate that only those birds that have experience of stealing the caches of other birds will engage in such re-caching.

Reproductive biology

Corvids are largely monogamous. However, the assertion that corvids "mate for life" is open to question, for there is clear evidence that some pair bonds are broken. One study estimated that one-third of black-billed magpie (Pica hudsonia) pairs "divorced," with one member of the pair seeking a mate in a better territory.

Pair bonds are often formed among flocks at a communal roost, or in noisy group gatherings just prior to the breeding season. In most species, a significant part of courtship behavior involves the male feeding the female—a preliminary to actual feeding when she is on the nest. The female may respond with begging or submissive quivering of the wings or tail, but this reaction is not found in all species. The male of the pair usually shows dominant behavior, such as openly stealing from the female's food store.

The typical corvid nest begins as a stick platform in the fork of a tree. Once the heap of strong sticks is firmly wedged in place, both birds make a bowl-shaped layer of strips of bark and roots, sometimes bound together with mud or animal dung. This is lined with a cup of soft materials such as grass, feathers, fur, and leaves. There are a number of mainly habitat-related adaptations to this basic model. Siberian jays (Perisoreus infaustus), one of several tree-nesting species of northern temperate zones, build especially thick nest cups insulated with lichens and reindeer hair. Pica magpies, which often nest in open habitat, add a domed roof to reduce the vulnerability of the nest to predators; this is clearly learned behavior, for inexperienced birds are more likely to build open nests. Tropical species usually nest in dense vegetation; their light, flimsy nests show they have no need of extra warmth or added protection.

Some corvids gain extra security or the ability to nest in a wider range of habitats by nesting in holes, cavities, ledges, or on the ground. Garrulus jays nest in tree hollows. Western jackdaws evolved the habit of nesting in chimneys and other cavities, possibly to reduce predation by larger carrion crows. Pyrrhocorax choughs generally nest in open habitat with few trees. For safety, they lay their eggs on cave ledges or deep cracks in cliffs. Even species that nest on the ground generally site the nest under a protective shelter, either under a bush or on a cliff ledge shielded from the wind. Only the Hume's ground-jay (Pseudopodoces humilis) digs a burrow in the ground where it lays its eggs.

Corvids lay between two and seven eggs; these are almost always incubated by the female, with the male feeding and guarding her. Hatching is asynchronous; it is common for the youngest and weakest young to die in the nest. The young are born blind, helpless, and either naked or with a light down. The adults are attentive parents, bringing food back to the nest in their throats. Smaller species fledge after about 20 days, but larger corvids may remain in the nest for five to seven weeks. Among solitary nesters, the young may remain with the parents for up to three months, becoming increasingly independent, before the family group breaks up.

Conservation status

Just over one-tenth of all corvids are classified as under some level of threat according to the IUCN, a reflection of the opportunism and adaptability of this family. However, the 13 species at risk and a further 11 Near Threatened species, are almost all in decline due to factors common to most threatened bird species.

More than any other family, crows are cast as villains of bird conservation, directly accused of causing the declines of other species. Such criticism is, at the very least, simplistic. Generally, crow predation or competition exacerbates a deteriorating situation caused by habitat alteration. Numbers of the endangered Cuban palm crow (Corvus minutus) have probably fallen because it is being outcompeted by the Cuban crow (Corvus nasicus). Yet such interspecific competition has almost certainly only happened because habitat destruction has resulted in overlapping ranges. The most serious threat to the Amami jay (Garrulus lidthi) is predation by other crows and mammals. However, numbers of large-billed crows (Corvus macrorhynchos) have recently increased, probably because of increased garbage disposal on the island.

The biggest threat facing endangered corvids, affecting 18 out of the 24 species at risk, is timber extraction, which is often followed by conversion of cleared ground to agriculture or development. When forest habitat is lost, and populations fall as a result, other factors take on greater significance. Fragmentation of habitat has severely depleted populations of the Sri Lanka magpie (Urocissa ornata) and the Flores crow (Corvus florensis) to the extent that brood-parasitism by the Asian koel (Eudynamys scolopacea) has a disproportionately large impact. Similarly, depredations caused by hunting for food by the white-necked crow (Corvus leucognaphalus) and Hispaniolan palm crow (Corvus palmarum) are now critical factors in their survival.

Habitat loss for development brings additional problems. The case of the Florida scrub-jay is a classic example. Between 1960 and 1980, the human population doubled as housing and the planting of citrus groves destroyed large areas of the bird's scrub habitat. Birds living in the remaining habitat, closer to human habitation, face extra pressure. Human disturbance, predation by feral cats, mortality on roads, and overgrowing of scrub because of fire prevention measures, added to the difficulties. Conservationists are working to ameliorate these problems by establishing controlled, rotational burning of scrub, and setting up a network of protected sites for the birds.

It is hard to see how some problems facing island endemics can be overcome. Added to habitat loss and other pressures are the threats facing small, geographically restricted populations of corvids from invasive species. The BirdLife International statement that "invasive species have entirely or partially caused the majority of all bird extinctions since 1800" appears prophetic for the Hawaiian crow (Corvus hawaiiensis) and Mariana crow (Corvus kubaryi). Both species have seen their populations eroded by habitat loss, disturbance, and persecution, among other factors. The introduction of the predatory brown tree snake (Boiga irregularis) on Guam will probably cause the Mariana crow to disappear from that island, and the population on neighboring Rota is at risk from introduced rats. The position of the Critically Endangered Hawaiian crow is even worse due to predation of nests by introduced rats and the Indian mongoose (Herpestes auropunctatus).

Significance to humans

Perhaps more than any other bird, the raven has from ancient times held a notable place in the minds of people in the Northern Hemisphere. This family has been linked inextricably with the lives, religions, and mythology of humans, probably even before ravens appeared on prehistoric cave paintings.

The omnipresence of corvids around human settlements, with crows and ravens often treated synonymously, has undoubtedly been a major factor in their pre-eminence in human mythology. In India, villagers believed the house crow was immortal, for although people died, the crows remained. Attributes given to corvids are legion; the common thread is the magical powers that are invested in these birds. The Innuit and ancient Chinese among others, associated crows with creation. Early Europeans believed that a crow flying around a house calling foretold a death. Viking mythology gives the god Odin two prophetic raven messengers, Hugin (thought) and Munin (memory), and in ancient Greece, the god Apollo had a prophetic raven. The gift of prophecy for both good and evil is powerfully realized among North and Central American aboriginal tribes, where the crow is totemic. Such was the power of crow medicine that the Cheyenne used crow rather than eagle feathers on their warbonnets.

Associations are often linked to observations of bird behavior. As a carrion-feeder, the northern raven waited around battlefields for a feast of human carcasses. On the Welsh and Scottish borderlands, it was named the Corby messenger, foretelling death and slaughter. This author testifies to the power of suggestion. Trapped by a blizzard in the mountains of Glencoe, Scotland, my fate on a cliff ledge appeared settled when, from the silent valley below, came the harsh "krok" of an apparently expectant raven.

Crows appear in the Koran and in the Bible, most memorably in the latter when a raven is sent by Noah to find land. An illustrated Bible from the early twelfth century shows a raven pecking at a drowned corpse. From Shakespeare—who mentioned crows 50 times within his plays—to Edgar Allen Poe, crows have fascinated humans.

Humans discovered early on that these intelligent birds could be tamed. The Roman philosopher Pliny gives instruction on teaching crows to speak. The diminutives in Mag-pie and Jack-daw reveal the familiarity that pet birds would command. Even today, the green magpie (Cissa chinensis) is commonly hunted for the cage bird trade.

Some corvid species have been persecuted because of economic damage to farm crops, livestock, poultry, game birds, and waterfowl. In 1938, following recommendations by the U.S. Biological Survey, American crow roosts in Oklahoma were bombed systematically. Seven years earlier, a contest to exterminate the black-billed magpie from British Columbia resulted in 1,033 being killed by just 12 hunters in one season. Persecution dates back much further; bounty hunters in England were given a farthing a crow in the reign of Henry VIII. The English poet William Wordsworth declared of the raven that "this carnivorous fowl is a great enemy to the lambs of these solitudes."

Although the indiscriminate persecution of corvids has now lessened—the Migratory Bird Treaty Act in North America was amended in 1972 to include protection for corvids for example—licensed control of a number of species is still accepted. Federal regulations in North America and national laws throughout Europe allow for killing corvids.

Species accounts

List of Species

Pinyon jay

Gymnorhinus cyanocephalus

subfamily

Corvinae

taxonomy

Gymnorhinus cyanocephalus Wied, 1841, Montana. Monotypic.

other common names

French: Geai des pinèdes; German: Nacktschnabelhäher; Spanish: Chara piñonera.

physical characteristics

9.75–10.92 in (25–28 cm); 3.6 oz (103 g). Uniform dull blue plumage is darkest on head, brightest on breast, crown, and forehead, and palest on rump. Throat is whitish. Relatively fine, sharply pointed bill is blackish, as are the legs and feet.

distribution

West-central United States. Central Oregon east to South Dakota; may be found as far south as Baja, California, to western Oklahoma.

habitat

Dry mountain slopes of pinyon, juniper, and yellow pine.

behavior

Highly gregarious, usually in large flocks, numbering up to 250 individuals. Flight is direct, accompanied by mewing calls.

feeding ecology and diet

Heavily dependent on conifer seeds. Will forage widely for invertebrates and other seeds, often visiting backyards.

reproductive biology

Cooperative breeder with young adults feeding chicks both before and after fledging. Colonial, well-spaced nests consisting of sticks and vegetation, cup lined with fine plants and wool. Generally three to four eggs laid February through May. Incubation 16 days; fledging 21 days.

conservation status

Not threatened. Locally common throughout its range.

significance to humans

Known by the Hopi as the bird of war because of its habit of mobbing predators.

Blue jay

Cyanocitta cristata

subfamily

Corvinae

taxonomy

Cyanocitta cristata Linnaeus, 1758, South Carolina. Four subspecies.

other common names

French: Geai bleu; German: Blauhäher; Spanish: Chara azul.

physical characteristics

9.36–11.7 in (24–30 cm); 2.27–3.8 oz (65–109 g). Upperparts and jaunty crest are purplish blue. Wings and tail are brighter blue and have prominent black barring; wings also have white spots. Chin, face, throat and underparts are grayish white. Long bill, legs, and feet are black.

distribution

Eastern and central North America, with Rocky Mountains forming broad western limit.

habitat

Woodland, parks, and suburbs.

behavior

Noisy and bold visitor to many backyards. Generally forages alone or in pairs.

feeding ecology and diet

Highly opportunistic feeder, supplementing a seed and nut diet with birds, mammals, invertebrates, and human garbage.

reproductive biology

Solitary tree nester. Uses mud to hold its twig, root, and feather nest together. Generally lays four to five eggs late March through early June. Incubation 16–18 days; fledging 18–21 days. Frequently double brooded.

conservation status

Not threatened. Very common, with range expanding north-westward.

significance to humans

Iconic status, with the Toronto Blue Jays baseball team, a record label, and a Beatles song all named after this bird.

Western scrub-jay

Aphelocoma californica

subfamily

Corvinae

taxonomy

Aphelocoma californica Vigors, 1839, California. Fifteen subspecies. Isolated Florida scrub-jay in peninsular Florida and the island scrub-jay (Aphelocoma insularis) on Santa Cruz considered separate species.

other common names

English: California jay; French: Geai buissonnier; German: Buschhäher; Spanish: Chara Pecho Rayado.

physical characteristics

10.53–12.09 in (27–31 cm); 2.8 oz (80 g). Upperparts, head, wings, and tail are dark blue; mantle and back are grayish brown. Head features a white "eyebrow" over a dark eye patch. Underparts are variable whitish, buff, and grayish. White throat is outlined with a blue necklace and there is a blue band on the chest. Bill, legs, and feet are blackish.

distribution

Western United States and northwest Mexico.

habitat

Mixed shrubs with trees.

behavior

Ground-feeder never far from cover, usually in pairs or family groups. Frequent loud, chattering calls. Pairs are strongly territorial.

feeding ecology and diet

Primarily acorns and pine seeds, often stored for later use. Also invertebrates, eggs and nestlings, small amphibians, reptiles, and mammals.

reproductive biology

Solitary breeder. Lays two to six eggs late March through early May in twig nest lined with plant matter. Incubation 16–19 days; fledging about 18 days.

conservation status

Not threatened; locally common.

significance to humans

Important, if inadvertent role as a planter of trees.

Eurasian jay

Garrulus glandarius

subfamily

Corvinae

taxonomy

Garrulus glandarius Linnaeus, 1758, Sweden. About 33 subspecies.

other common names

English: Red-crowned jay (in India); French: Geai des chênes; German: Eichelhaher; Spanish: Arrendejo Común.

physical characteristics

12.48–14.04 in (32–36 cm); 4.9–6.55 oz (140–187 g). Subspecies vary significantly in plumage color and pattern, but generally this bird has a pinkish brown body, white wing patches, blue shoulders, and a black tail. The head features a black moustache and crown feathers that appear ruffled when erect. Bill is dark brownish horn, and legs and feet are fleshy-brown.

distribution

Most widespread of all jays, found in all but northernmost parts of Europe, north Africa, Middle East, central and Southeast Asia.

habitat

Both deciduous and coniferous woodland.

behavior

Normally shy and solitary. Presence given away by loud, screeching call.

feeding ecology and diet

Eats and stores enormous quantities of acorns. Also feeds on other seeds, invertebrates, eggs, and nestlings.

reproductive biology

Solitary nester, building platform twig nest in fork of tree. Lays three to seven eggs April through May. Incubation 16–19 days; fledging 18–23 days.

conservation status

Not threatened. Common to abundant in most of its range.

significance to humans

Thought to be primarily responsible for planting of Old World oak forests. Individuals bury thousands of acorns in fall for later consumption.

Gray jay

Perisoreus canadensis

subfamily

Corvinae

taxonomy

Perisoreus canadensis Linnaeus, 1766, Canada. Eight subspecies.

other common names

English: Canada jay, whiskey-jack, venison-hawk; French: Mésangeai du Canada; German: Meisenhäher; Spanish: Chara gris.

physical characteristics

9.75–10.92 in (25–28 cm); 2.17–2.5 oz (62–73 g). Upperparts, wings, and tail are dark gray; underparts are lighter gray. Head is pale gray with a black patch on crown and nape; throat is white. Subspecies vary most noticeable in the extent of the black head patch.

distribution

Conifer forests of Canada, Alaska, and northern and western United States.

habitat

Coniferous forests away from human habitation.

behavior

Usually forages unobtrusively in pairs or family groups.

feeding ecology and diet

Invertebrates, small mammals, and birds. Also berries which are "glued" to trees for future consumption, using sticky saliva.

reproductive biology

Solitary nester. Lays two to five eggs March through April in twig nest which is well insulated with mosses, lichens, fur, and feathers. Incubation 16–18 days; fledging about 15 days.

conservation status

Not threatened. Locally common over a wide range.

significance to humans

Bold scavenging from humans has earned it the name "camp robber."

Green magpie

Cissa chinensis

subfamily

Corvinae

taxonomy

Cissa chinensis Boddaert, 1783, Mergui, Tenasserim, Myanmar. Five subspecies.

other common names

English: Green hunting crow, hunting cissa; French: Pirolle verte; German: Jagdelster; Spanish: Urraca Verde.

physical characteristics

14.43–15.21 in (37–39 cm); male 4.55–4.65 oz (130–133 g), female 4.2–4.34 oz (120–124 g). A bulky-bodied bright green bird with a wide black mask, chestnut wings, and long, graduated tail. Bill, legs, and feet are bright red.

distribution

Mainland tropical Southeast Asia, also Borneo and Sumatra.

habitat

Lowland and hill forest.

behavior

Shy bird that gives whistling call from dense undergrowth. Small groups move through forest outside breeding season in company with other bird species.

feeding ecology and diet

Hunts low in undergrowth for insects. Also small birds, reptiles, amphibians, fruit, and berries.

reproductive biology

Solitary nester on platform nest often built in bamboo or vines. Lays three to seven eggs January through April. No information known about incubation or fledging.

conservation status

Not threatened, but uncommon throughout its range.

significance to humans

Commonly trapped for the cage bird trade, where it is known as a cissa.

Azure-winged magpie

Cyanopica cyana

subfamily

Corvinae

taxonomy

Cyanopica cyana Pallas, 1776, Dauria. Nine subspecies.

other common names

French: Pie bleue; German: Blauelster; Spanish: Urraca de Rabo Largo.

physical characteristics

13.26 in (34 cm); 2.17–2.87 oz (62–82 g). A distinctive bird with gray to pinkish buff upperparts, black hood, white throat, pale blue wings, and long, graduated pale blue tail. Bill, legs, and feet are black.

distribution

Two separate populations. Western distribution limited to Spain and Portugal. May once have been linked with eastern population, which is distributed widely from Mongolia and eastern Russia through most of China and Korea to Japan.

habitat

Woodland and forest edge. Iberian form found in open country.

behavior

Highly gregarious magpie, with parties numbering up to 100 outside breeding season. Stays close to cover in most parts of its range, although a bold scavenger in Chinese and Japanese towns and cities.

feeding ecology and diet

Insects, fruit, seeds, and berries.

reproductive biology

Nests in colonies, with each pair selecting its own tree to build a stick and twig nest, held together with mud. Generally lays five to seven eggs March through June; double-brooded in Far East. Incubation 15 days; fledging about 16 days. Young adults from previous year's brood act as helpers feeding young.

conservation status

Not threatened. Common and increasing in number over most of its range.

significance to humans

None known.

Rufous treepie

Dendrocitta vagabunda

subfamily

Corvinae

taxonomy

Dendrocitta vagabunda Latham, 1790, India. Nine subspecies.

other common names

English: Indian treepie; French: Témia vagabonde; German: Wanderelster; Spanish: Urraca vagabunda.

physical characteristics

17.94–19.5 in (46–50 cm); 3.15–4.55 oz (90–130 g). Upper-parts are rusty-orange; underparts are paler and buffy. Head, neck, breast, and upper mantle are blackish. Wing coverts and tertials are pale, silvery gray; the rest of the wing is brownish black. Central tail feathers are pale gray ending in a wide, black terminal band; outer tail feathers have more black. Bill is dark gray or blackish; legs and feet are brownish black.

distribution

Widely distributed through Pakistan, India, Burma, and western Thailand. Patchier in Laos, Cambodia, and Vietnam.

habitat

Light woodland, open fields with trees, villages, towns, and cities.

behavior

Moves in pairs or family parties, uttering loud calls. Largely arboreal, most often seen flying between trees, or perching high in canopy.

feeding ecology and diet

Very wide diet, including invertebrates, small birds, mammals, reptiles, and amphibians, nuts, berries, carrion.

reproductive biology

Solitary nester usually on lone tree. Generally lays four to five eggs February through May in stick nest. Incubation and fledging periods unknown.

conservation status

Not threatened. Very common in western part of range, common elsewhere.

significance to humans

None known.

Eurasian magpie

Pica pica

subfamily

Corvinae

taxonomy

Pica pica Linnaeus, 1758, Sweden. Twelve subspecies. Until 2000, the black-billed magpie of northwest North America was considered a subspecies.

other common names

English: Common magpie; French: Pie bavarde; German: Elster; Spanish: Urraca de Pico Negro.

physical characteristics

16.77–19.5 in (43–50 cm); 6.3–9.63 oz (180–275 g). Plumage is mostly black with white belly, sides, and scapulars. The black head, neck, mantle, and breast have a weak green and purple

sheen; the black wings and tail are highly glossed with green/blue/purple iridescence. Bill, legs, and feet are black.

distribution

One of the most widespread of corvids, found throughout Europe and much of Asia, and northwest Africa.

habitat

Generally found wherever there are trees, although avoids dense forest.

behavior

Presence often betrayed by raucous "chacking" call. Groups of magpies often harass gulls or kites to make them drop food.

feeding ecology and diet

Omnivorous diet includes invertebrates, fruit and berries, birds, mammals, carrion including road kills; scavenges human garbage.

reproductive biology

Solitary nester. Lays between two to 13, but generally eight to nine eggs March through May in dome-shaped twig nest. Incubation 14–23 days; fledging 10 days; young stay with parents for a short time after leaving nest. Other nonbreeding adults allowed in breeding territory.

conservation status

Not threatened; common to abundant.

significance to humans

Numbers controlled where perceived as a threat to game birds in Europe.

Hume's ground-jay

Pseudopodoces humilis

subfamily

Corvinae

taxonomy

Pseudopodoces humilis Hume, 1871, Sinkiang. Probably monotypic.

other common names

English: Little ground-jay, Tibetan ground-jay, Hume's groundpecker; French: Podoce de Hume; German: Höhlenhäher; Spanish: Arrandejo Terrestre de Hume.

physical characteristics

7.4 in (19 cm); 1.47–1.61 oz (42–46 g). The soft, slightly fluffy body plumage is dull brownish above and off-white below. Wings are darker brown and the tail is white with dark brown central feathers. The black bill is short, thin, and distinctly curved. Legs and feet also are black.

distribution

Tibetan Plateau of China, Nepal, and India.

habitat

Grassy, boulder-strewn mountain slopes.

behavior

Hops and perches between boulders, flicking wings and tail on landing.

feeding ecology and diet

Probes on ground using long bill in search of invertebrates.

reproductive biology

Digs long tunnel in bank, wall or building to build grass and moss nest at end. Lays four to six eggs May through June. Incubation and fledging periods unknown.

conservation status

Not threatened; common.

significance to humans

None known.

Spotted nutcracker

Nucifraga caryocatactes

subfamily

Corvinae

taxonomy

Nucifraga caryocatactes Linnaeus 1758, Sweden. Eight subspecies.

other common names

English: Nutcracker, Eurasian nutcracker, spotted nutcracker; French: Cassenoix moucheté; German: Tannenhäher; Spanish: Cascanueces Moteado.

physical characteristics

12.48–13.26 in (32–34 cm); 4.34–7 oz (124–200 g). Body plumage is dark brown profusely spotted with white; lower belly and undertail-coverts are white. Wings are glossy black with white-tipped coverts. Tail is also glossy black with white feather tips, increasing in extent toward the outermost. Bill, legs, and feet are black.

distribution

Coniferous forests of Europe and Asia. North American equivalent is Clark's nutcracker.

habitat

Coniferous forests. Widely dispersed during irruptions following failure of seed harvest.

behavior

Wary, but perches on conspicuous treetops. Holds year-round territory, keeping several stores of nuts and seeds.

feeding ecology and diet

Heavily reliant on conifer seeds and hazel nuts, which are stored as winter supply. Insects and berries eaten seasonally.

reproductive biology

Solitary nester. Generally lays three to four eggs March through May in stick nest woven together with plant stems.

Cup lined with moss and grass. Incubation 16–18 days; fledging about 23 days. Young remain with parents for rest of summer.

conservation status

Not threatened. Abundant throughout its range.

significance to humans

A significant planter of conifers thanks to its habit of storing pine seed underground.

Red-billed chough

Pyrrhocorax pyrrhocorax

subfamily

Corvinae

taxonomy

Pyrrhocorax pyrrhocorax Linnaeus, 1758, England. Eight subspecies.

other common names

English: Chough; French: Crave à bec rouge; German: Alpenkrähe; Spanish: Chova piquirroja.

physical characteristics

14.04–15.6 in (36–40 cm); 9.97–13.3 oz (285–380 g). Plumage is velvet-black with a slight bluish purple to greenish gloss on the body; wings and tail are glossier. Slender, curved bill is red, as are legs and feet.

distribution

Widespread in mountainous areas of central and western Asia. Patchy distribution in Europe and northwest Africa.

habitat

Rocky, mountainous areas with adjacent animal pasture. Western European populations use sea cliffs.

behavior

Territorial during breeding season, but allows third adult in territory. Highly gregarious at other times and roosts colonially in caves or rock crevices.

feeding ecology and diet

Soil feeder on ants, beetles, worms, and other invertebrates. Often finds food in animal dung.

reproductive biology

Solitary nester, constructing stick and animal hair nest at back of cave. Generally lays three to four eggs March through April. Incubation 17–21 days; fledging 36–41 days.

conservation status

Not threatened. Common in Asia, populations declining in Europe following changes in land use.

significance to humans

None known.

Western jackdaw

Corvus monedula

subfamily

Corvinae

taxonomy

Corvus monedula Linnaeus, 1758, Sweden. Four subspecies usually recognized.

other common names

French: Choucas des tours; German: Dohle; Spanish: Grajilla Común.

physical characteristics

13.26–15.21 in (34–39 cm); 4.86–9.27 oz (139–265 g). Upper-parts are grayish black with a slight bluish gloss. Head has a black forecrown and dark gray rear crown, nape, and sides. Wings and tail are black and glossy. Underparts are grayish black. The short bill is black, as are the legs and feet.

distribution

Europe, western Asia, North Africa.

habitat

Wide variety of open country with trees, including areas of human habitation.

behavior

Sociable groups frequently engage in agile, tumbling flight display, giving loud calls.

feeding ecology and diet

Mainly granivorous, except during breeding season when it takes moth caterpillars from tree foliage.

reproductive biology

Semicolonial. Stick nests built in tree holes, cliff faces, or artificial structures. Generally four eggs April through May. Incubation 17–19 days; fledging about 30 days.

conservation status

Not threatened. Abundant; appears to be spreading broadly north and eastward.

significance to humans

Regularly nests in chimneys of inhabited buildings.

House crow

Corvus splendens

subfamily

Corvinae

taxonomy

Corvus splendens Vieillot, 1817, Bengal. Four or five subspecies recognized.

other common names

French: Corbeau familier; German: Glanzkrähe; Spanish: Corneja India.

physical characteristics

15.6 in (40 cm); 8.57–12.07 oz (245–371 g). Plumage is black except for the nape, sides of the head, and breast, which are gray. Bill, legs, and feet also black.

distribution

Iran to India, Pakistan and Burma, self-introduced to East Africa, Indian Ocean islands, Malaysia, and South Africa.

habitat

Wholly dependent on human habitation; consequently found in villages, towns, and cities throughout its range.

behavior

Highly vocal, gregarious birds, seemingly unafraid of humans. Will attack and chase off any large bird of prey.

feeding ecology and diet

Omnivorous. Diet includes seeds, fruit, grain, nectar, berries, bird's eggs, nestlings, mammals, reptiles, amphibians, fish, insects, wide range of carrion.

reproductive biology

Solitary nester except in areas of high population density. Will use trees, buildings, or other artificial structures for rough stick nest. Three to four eggs March through July. Incubation 16–17 days; fledging 21–28 days.

conservation status

Not threatened. Abundant throughout range.

significance to humans

Regarded as a major agricultural and human health pest in self-introduced areas. In South Africa, birds have been reported taking food from school children, killing chicks of domestic fowls, and repeatedly dive-bombing any person near the nest.

Rook

Corvus frugilegus

subfamily

Corvinae

taxonomy

Corvus frugilegus Linnaeus, 1758, Sweden. Two subspecies.

other common names

French: Corbeau freux; German: Saatkrähe; Spanish: Graja Común.

physical characteristics

18.33 in (47 cm); 11.8–18.58 oz (337–531 g). Entire plumage is black and highly glossed with metallic blue, green, and purple. Base of the bill, chin, and loral region are bare, giving the forecrown a slightly peaked appearance. Bill is whitish at the base shading to dusky over the terminal half. Legs and feet are black.

distribution

In all but the most mountainous areas of Europe and Asia.

habitat

Farmland with scattered trees and wooded steppe.

behavior

Significant fall migrant, flying by day from northern Europe and Asia, to western Europe, the Middle East, and southern Asia. In the Seine-et-Marne district of France, the breeding population was estimated at 10,000; the winter population 500,000.

feeding ecology and diet

Soil feeder on invertebrates, seed, grain.

reproductive biology

Nests colonially in rookeries; there are generally at least 20 nests densely clustered around the tops of several trees. Nests used repeatedly in successive years. Lays two to seven eggs in grass and leaf cup within bulky stick nest. Incubation 16–18 days; fledging 32–33 days.

conservation status

Not threatened. Abundant to localized in Europe. Evidence of decline in eastern Asia.

significance to humans

Often persecuted because of its tendency to feed on cereal seed.

American crow

Corvus brachyrhynchos

subfamily

Corvinae

taxonomy

Corvus brachyrhynchos Brehm, 1822, Boston, Massachusetts. Four subspecies.

other common names

English: Common crow; French: Corneille d'Amérique; German: Amerikanerkrähe; Spanish: Cuervo Americano.

physical characteristics

15.21–19.11 in (39–49 cm); male 1 lb (458 g), female 15.33 oz (438 g). Plumage is entirely black with a light violet-blue gloss. Wings have a more greenish blue gloss. Prominent bristles cover the basal third of the upper mandible. Bill, legs, and feet are black.

distribution

Widespread throughout North America. Canadian birds migrate to central United States and Atlantic seaboard.

habitat

Adapted to most habitats with the exception of arid areas and dense forest.

behavior

Gathers in huge communal roosts in winter, sometimes containing tens of thousands of birds. Individuals will fly up to 50 mi (80 km) to the roost.

feeding ecology and diet

Omnivorous. Main food items include insects, bird nestlings and eggs, and carrion.

reproductive biology

Solitary nester. Builds stick nest in fork of tree, bush, or occasionally artificial structure. Generally lays four to five eggs in cup made of roots, grass, and animal hair February through June. Incubation 18 days; fledging 28–35 days.

conservation status

Not threatened. Abundant throughout its range.

significance to humans

Heavily persecuted as an agricultural pest, largely because its diet includes grain, game birds, and poultry.

Carrion crow

Corvus corone

subfamily

Corvinae

taxonomy

Corvus corone Linnaeus, 1758, England. Two subspecies.

other common names

English: Eurasian crow; French: Corneille noire; German: Aaskrähe; Spanish: Corneja Cenicienta.

physical characteristics

18.72–21.84 in (48–56 cm); male 1–1.4 lb (465–650 g), female 1–1.3 lb (450–600 g). Plumage is entirely black with a bluish to purplish sheen. Conspicuous bristles cover base of culmen and basal third of upper mandible. Bill, legs, and feet are black.

distribution

Widely distributed throughout Europe and Asia. The black nominate form is replaced in central Europe and western Asia by the gray and black race known as the hooded crow.

habitat

Huge diversity of habitats, ranging from the centers of cities to sea cliffs.

behavior

Some territories held year-round. Most defended only during breeding season, especially aggressively when nest-building. Considerable territorial rivalry between corvids; crows and black-billed magpies will destroy each other's nests and predate eggs and chicks.

feeding ecology and diet

Mainly carnivorous. Diet includes invertebrates, mollusks, amphibians, fish, birds, and mammals. Also carrion and human garbage.

reproductive biology

Solitary nester. Stick nest in tree or bush, cliff ledges, or buildings. Generally lays four to five eggs April through May in cup made of moss, wool, animal hair, and roots. Incubation 17–19 days; fledging 32–36 days.

conservation status

Not threatened. Common throughout its range.

significance to humans

Perceived as a threat to livestock and game birds throughout its range and heavily persecuted.

Torresian crow

Corvus orru

subfamily

Corvinae

taxonomy

Corvus orru Bonaparte, 1851, New Guinea. Four subspecies.

other common names

English: Australian crow; French: Corbeau de Torres; German: Salvadorikrähe; Spanish: Cuervo Australiano.

physical characteristics

19.5–21.45 in (50–55 cm); 15.05–23.45 oz (430–670 g). Plumage is entirely black with a strong purple or bluish purple gloss. Bill, legs, and feet are also black.

distribution

Australia, New Guinea, and neighboring islands of Indonesia.

habitat

Edges of rainforest, open forest, woodlands and tall scrub, coastal margins, ranges and gorges of arid areas, human settlements.

behavior

The only one of five very similar Australian crow species to adopt a curious post-alighting behavior. The Torresian crow lands, then promptly begins shuffling its wings up and down.

feeding ecology and diet

Omnivorous, feeding mainly on insects, fruit, seeds, and carrion.

reproductive biology

Solitary tree nester. Lays two to five eggs. Incubation is 16–20 days; fledging is 34–38 days.

conservation status

Listed as Near Threatened in the Action Plan for Australian Birds 2000.

significance to humans

Considered an agricultural pest, as it feeds on grain, peanuts, and fruit.

Northern raven

Corvus corax

subfamily

Corvinae

taxonomy

Corvus corax Linnaeus, 1758, Sweden. Eight subspecies may be recognized.

other common names

French: Grand corbeau; German: Kolkrabe; Spanish: Cuervo Común.

physical characteristics

22.62–26.91 in (58–69 cm); 2.02–3.43 lb (92–156 g). Plumage is glossy black. Prominent nasal bristles cover basal third of upper mandible. Long, heavy bill is black and the distal part of the culmen is strongly decurved. Legs and feet are also black.

distribution

Most widespread corvid found in most of the Northern Hemisphere.

habitat

A wide variety of habitats, generally open and away from human habitation, including treeless tundra.

behavior

Established pairs remain on large, usually well-spaced territories. The familiar guttural "krok" call is the most recognizable of a highly varied vocal repertoire.

feeding ecology and diet

Mainly carrion feeder, but also eats live prey and plant material. Powerful beak used to tear carrion apart and kill live animals. Often robs other predators of food. Seeds and berries seasonally important.

reproductive biology

Solitary nester, constructing enormous stick nest in tree or bush, on cliff ledge, or rarely on the ground. Lays three to seven eggs early spring. Incubation 18–21 days; fledging 35–42 days.

conservation status

Thinly distributed throughout range, but not at risk, despite often heavy persecution.

significance to humans

Mistakenly thought to kill healthy young livestock and consequently persecuted.

Resources

Books

Bent, A. C. Life Histories of North American Jays, Crows, and Titmice. Washington, DC: Smithsonian Institution, 1946.

Birkhead, T. The Magpies: The Ecology and Behavior of Black-Billed and Yellow-Billed Magpies. New York: Academic Press, 1991.

Coombs, F. The Crows: A Study of the Corvids of Europe. London: Batsford, 1978.

Cramp, S., and C. M. Perrins. "A Handbook of the Birds of Europe, the Middle East and North Africa." In The Birds of the Western Palearctic, Vol. 8, Crows to Finches. Oxford, UK: Oxford University Press, 1994.

Goodwin, D. Crows of the World. London: British Museum (Natural History), 1986.

Heinrich, B. Ravens in Winter. New York: Summit, 1989.

Madge, S., and H. Burn. Crows and Jays: A Guide to the Crows, Jays and Magpies of the World. London: Christopher Helm, 1995.

Marzluff, J. M., and R. F. Balda. The Pinyon Jay. Orlando, FL: Academic Press, 1992.

Palmer, J. D. Animal Wisdom: The Definitive Guide to the Myth, Folklore and Medicine Power of Animals. London: Thorsons, 2001.

Ratcliffe, D. The Raven. Orlando, FL: Academic Press, 1997.

Savage, C. Bird Brains: The Intelligence of Crows, Ravens, Magpies and Jays. San Francisco: Sierra Club Books, 1997.

Sibley, C. G., and J. E. Ahlquist. Phylogeny and Classification of Birds: A Study in Molecular Evolution. New Haven and London: Yale University Press, 1990.

Yapp, B. Birds in Medieval Manuscripts. London: British Library, 1981.

Periodicals

Emery, N. J., and N. S. Clayton. "Effects of Experience and Social Context on Prospective Caching Strategies by Scrub Jays." Nature 414 (November 22, 2001): 443–446.

Sonerud, G.A, C. A. Smedshaug, and O. G. Brathen. "Ignorant Hooded Crows Follow Knowledgeable Roost-Mates to Food: Support for the Information Centre Hypothesis." Proceedings of the Royal Society of London B 268, no. 1469 (2001): 827–831.

Organizations

Roberts VII Project, Percy FitzPatrick Institute of African Ornithology, University of Cape Town. Rondebosch 7701, South Africa. Fax: (021) 650 3295. E-mail: [email protected] Web site: <http://www.uct.ac.za/depts/fitzpatrick/docs/r549.html>

Other

BirdLife International. March 18, 2002. <http://www.birdlife.net>.

McGowan, K. "Demographic and Behavioral Comparisons of Urban and Rural American Crows in New York: Abstracts from the Symposium at the 117th Stated Meeting of the American Ornithologists' Union, Ithaca, NY, 14 August 1999." Abstracts of Presented Papers Given By Kevin J. Mcgowan. March 18, 2002 <http://www.birds.cornell.edu/crows/aou99.htm.>

Derek William Niemann, BA