Corvidae in The Bird Book by Chester A. Reed

CROWS, JAYS, MAGPIES, ETC. Family CORVIDÆ.

Magpie.

475. Magpie. Pica pica hudsonia.

Range.–Western North America from the Great Plains to the Pacific and from Alaska to Arizona and New Mexico.

Grayish white.

These large handsome birds have the entire head, neck and breast velvety black, abruptly defined against the white underparts. The back, wings and tail are greenish or bluish black, and the scapulars, white; length of bird 20 inches. They are well known throughout the west, where their bold and thievish habits always excite comment. They nest in bushes and trees at low elevations from the ground, making a very large nest of sticks, with an opening on the side, and the interior is made of weeds and mud, lined with fine grasses; these nests often reach a diameter of three feet and are made of quite large sticks. During April or May, they lay from four to eight grayish white eggs, plentifully spotted with brown and drab. Size 1.25 x .90.

Grayish white.

476. Yellow-billed Magpie. Pica nuttalli.

Range.–Middle parts of California, west of the Sierra Nevadas.

This species is slightly smaller than the last and has a yellowish bill and lores, otherwise being precisely like the more common species. Their habits do not differ from those of the other, the nests are the same and the eggs are indistinguishable. Size 1.25 x .88.

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NEST OF AMERICAN MAGPIE.
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YOUNG BLUE JAYS.
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Blue Jay.

477. Blue Jay. Cyanocitta cristata cristata.

Range.–North America, east of the Plains and north to Hudson Bay; resident and very abundant in its United States range.

Greenish buff.

These beautiful and bold marauders are too well known to need description, suffice it to say that they are the most beautiful of North American Jays; but beneath their handsome plumage beats a heart as cruel and cunning as that in any bird of prey. In the fall, winter and spring, their food consists largely of acorns, chestnuts, berries, seeds, grain, insects, lizards, etc., but during the summer months they destroy and devour a great many eggs and young of the smaller birds, their taste for which, being so great that they are known to watch a nest until the full complement of eggs is laid before making their theft. They nest in open woods or clumps of trees, indifferently, in pines or young trees, building most often below twenty feet from the ground; the nests are made of twigs and rootlets, lined with fine rootlets. During May they lay from four to six eggs of a greenish buff color spotted with olive brown. Size 1.10 x .80.

477a. Florida Blue Jay. Cyanocitta cristata florincola.

Range.–Florida and the Gulf coast.

The nesting habits and eggs of this smaller sub-species are the same as those of the northern Blue Jay. Like our birds, they frequently nest near habitations.

478. Steller’s Jay. Cyanocitta stelleri stelleri.

Range.–Pacific coast from southern California to Alaska; resident and breeding throughout its range.

Greenish blue.

All the members of this sub-species are similar in plumage, having a sooty black head, crest and neck, shading insensibly into dark bluish on the back and underparts, and brighter blue on the wings and tail. They usually have a few streaks or spots of pale blue on the forehead. They are just as noisy, bold and thievish as the eastern Jay and are also excellent mimics like the latter. They nest in fir trees at any height from the ground and in April or May deposit their three to six greenish blue eggs which are spotted with various shades of brown. Size 1.25 x .90. Their nests are more bulky than those of the eastern Jay and are usually made of larger sticks and held together with some mud.

478a. Blue-fronted Jay. Cyanocitta stelleri frontalis.

Range.–Coast ranges of California and Oregon.

The nesting habits and eggs of this variety are indistinguishable from those of the preceding. The bird has more blue on the forehead.

478b. Long-crested Jay. Cyanocitta stelleri diademata.

Range.–Southern Rocky Mountains from Arizona to Wyoming.

No general difference can be found between the eggs of this species and the Steller Jay, and the nests of each are constructed similarly and in like situations.

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YOUNG BLUE JAYS.
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BLUE JAY.
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Florida Jay.

478c. Black-headed Jay. Cyanocitta stelleri annectens.

Range.–Northern Rocky Mountains from northern Colorado to British Columbia.

The eggs of this sub-species cannot be identified from those of the other varieties. Like the others, their nests are made of sticks plastered together with mud and lined with weeds and rootlets.

478d. Queen Charlotte Jay. Cyanocitta stelleri carlottæ.

Range.–Queen Charlotte Islands, British Columbia.

479. Florida Jay. Aphelocoma cyanea.

Range.–Locally distributed in Florida.

Greenish blue.

All the birds of this genus have no crests or decided markings, are white or grayish below, and more or less intense blue above, with the back grayish or brownish blue. This species is 11.5 inches long, has a pale blue crown and a nearly white forehead. It has a very limited distribution, being confined chiefly to the coast districts of middle Florida, and very abundant in some localities and rare in adjoining ones. They build shallow structures of small sticks and weeds lined with fine rootlets and placed at low elevations in bushes or scrubby trees. The three or four eggs, which are laid in April or May are dull greenish blue, marked with olive brown. Size 1.00 x .80. Data.–Titusville, Fla., April 17, 1899. Nest of sticks in a scrub oak, five feet from the ground.

480-487.

480. Woodhouse’s Jay. Aphelocoma woodhousei.

Range.–United States west of the Rockies and from Oregon and Wyoming to Mexico.

Bluish green.

This species has the crown and forehead bluish, and the underparts gray, streaked with bluish gray on the breast. It is also larger than the last, being 12 inches long. They are very abundant in the Great Basin between the Rockies and the Sierra Nevadas, breeding during April or May in scrubby trees or bushes at low elevations and generally near streams. They lay from three to five eggs of a dull bluish green color, spotted with umber and lilac gray. Size 1.08 x .80. Data.–Iron County, Utah, May 3, 1897. 4 eggs. Nest of sticks and weeds in a small pine tree.

Page 307 480.1. Blue-eared Jay. Aphelocoma cyanotis.

482–484a–485.

Range.–Interior of Mexico north to the southern boundary of Texas.

The nesting habits of this species are the same as those of the others of the genus and the eggs are similar but the markings are generally more prominent and larger. Size 1.10 × .80.

480.2. Texas Jay. Aphelocoma texana.

Range.–Southeastern Texas.

It is not likely that the eggs of this species differ essentially from those of many of the others.

481. California Jay. Aphelocoma californica californica.

Range.–Pacific coast of California and Washington.

Bright bluish green.

This is a very abundant species both about habitations and in low woodlands. They are very bold and familiar, stealing everything they may take a fancy to, and frequently robbing smaller birds of their eggs and young. They are said to be more tame and familiar than the eastern Blue Jay, thereby bringing their bad habits much more frequently to the attention of the masses. They nest most often in bushes or low trees, but not as a rule, far above the ground. Their eggs are a bright bluish green color, speckled and spotted with brownish and lavender. Size 1.10 × .80.

481a. Xantus’s Jay. Aphelocoma californica hypoleuca.

Range.–Lower California.

The habits and nests and eggs of this lighter colored variety do not differ from those of the California Jay.

481b. Belding’s Jay. Aphelocoma californica obscura.

Range.–San Pedro Martir Mts. Lower California.

A darker variety of the California Jay, whose nesting habits will not differ in any essential particular.

481.1. Santa Cruz Jay. Aphelocoma insularis.

Range.–Santa Cruz Island, California.

Greenish blue.

This species is the largest and darkest colored bird of the genus Aphelocoma. It is said to be a very abundant species on the island from which it takes its name, and to have the habits and traits common to all the members of the Jay family. The nesting habits are the same as those of the others, but the eggs are slightly larger, averaging 1.15 × .85. Set of three in the collection of John Lewis Childs, taken by R. H. Beck on May 10, 1897.

482. Arizona Jay. Aphelocoma sieberi arizonæ.

Range.–Arizona and southwestern New Mexico south into Mexico.

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Green Jay.

482a. Couch’s Jay. Aphelocoma sieberi couchi.

Range.–Eastern Mexico, north to western Texas.

483. Green Jay. Xanthoura luxuosa glaucescens.

Range.–Northeastern Mexico and the Lower Rio Grande Valley in Texas.

Grayish buff.

This handsome species has a bright blue crown and patches under the eyes, the rest of the upper parts being greenish; throat and sides of head black, underparts greenish white. This gaudy and noisy bird has all the habits common to other Jays including that of robbing birds’ nests. They build generally in tangled thickets or low bushes, placing their nests at a low elevation and making them of twigs, weeds, moss, etc., lined with fine rootlets. Their four or five eggs, which are laid during April or May, are grayish buff in color, spotted with various shades of brown and lavender gray. Size 1.20 × .85.

484. Canada Jay. Perisoreus canadensis canadensis.

Range.–Southeastern British Provinces and the adjacent portions of the United States; west to the Rockies.

Grayish.
Canada Jay.

This is the bird that is well known to hunters of “big game” by various names such as “Whiskey Jack”, “Moose Bird”, “Camp Robber”, etc. During the winter months, owing to the scarcity of food, their thieving propensities are greatly enhanced and they remove everything from the camps, which looks as though it might be edible. Birds of this genus are smoky gray on the back and lighter below, shading to white on the throat; the forehead and part of the crown is white and the nape blackish. Their nests are placed at low elevations in bushes or fir trees, and are usually very different from any of the preceding Jays’ nests. They are nearly as high as wide, and are made of small twigs, moss, catkins, weeds and feathers making a soft spongy mass which is placed in an upright crotch. The eggs are a yellowish gray color spotted and blotched with brown and grayish. Size 1.15 × .80. Data.–Innisfail, Alberta, March 12, 1903. Nest a beautiful structure of twigs, moss and feathers in a willow bush, 6 feet from the ground. The thermometer registered 32 below zero the day the eggs were taken. Collector, W. Blackwood.

Page 309 484a. Rocky Mountain Jay. Perisoreus canadensis capitalis.Range.–Rocky Mountains from Montana to Arizona.This variety has the whole crown white and only a small amount of blackish on the nape. Its nesting habits and eggs are precisely like those of the last.


NEST AND EGGS OF CANADA JAY SHOWING CONSTRUCTION.

484b. Alaska Jay. Perisoreus canadensis fumifrons.

Range.–Alaska.

A very similar bird to the Canada Jay but with the forehead yellowish or duller; the nests and eggs are like those of the others of the genus.

484c. Labrador Jay. Perisoreus canadensis nigricapillus.

Range.–Labrador.

This is a darker variety of the Canada Jay. Its eggs cannot be distinguished from those of any of the others of the genus.

485. Oregon Jay. Perisoreus obscurus obscurus.

Range.–Mountain ranges from northern California to British Columbia.

These birds are very similar to canadensis but have the whole underparts white. Like the Canada Jays they appear to be wholly fearless and pay little or no attention to the presence of mankind. Their nesting habits and eggs are the same as the preceding except that they have generally been found nesting near the tops of tall fir trees. Size of eggs, 1.05 × .80.

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YOUNG CROWS
Page 311 485a. Gray Jay. Perisoreus obscurus griseus.Range.–British Columbia to northern California, east of the coast ranges.This bird is said to be larger and grayer than the preceding.

486. Raven. Corvus corax sinuatus.

Range.–North America west of the Rockies and from British Columbia southward.

Pale greenish white.

The Raven is like a very large Crow, length 24 inches, but has the feathers on the neck lengthened and stiffened. Their habits are similar to those of the Crow, but more dignified, and they remain mated for life. Besides grasshoppers and worms, they feed largely upon animal matter such as lizards, shell fish, frogs, eggs and young of birds, and carrion. They nest on ledges of high inaccessible cliffs or the tops of tall trees, making large nests of sticks lined with smaller ones and hair or wool; the eggs are laid in April or May, number from four to seven, and are light greenish in color, blotched with umber and drab. Size 1.95 × 1.25.

486a. Northern Raven. Corvus corax principalis.

Range.–Eastern North America chiefly north of the United States and northwest to Alaska; south on some of the higher ranges to Georgia.

This variety is like the last but is larger. They are not nearly as abundant as the western form and are very rare within the United States. A few pairs still breed on some of the rocky islands off the coast of Maine; more off New Brunswick and Newfoundland, and they are quite common on the cliffs of Labrador and Alaska. Their nesting habits and eggs are like those of the last.

487. White-necked Raven. Corvus cryptoleucus.

Range.–Mexico and the border of the United States; north to eastern Kansas.

Pale bluish green.

This small Raven is of about the size of the Crow, and has the bases of the neck feathers white. They are very abundant in some localities, especially in southern Arizona. Their food consists chiefly of animal matter, the same as the large Ravens, and they are not nearly as shy, frequently feeding in camps upon refuse which is thrown out to them. They build at low elevations in any tree, but preferably in mesquites, making their nests of sticks and lining them with hair, leaves, bark, wool or anything soft. During June they lay from four to six pale bluish green eggs, generally sparingly spotted or scratched with dark brown and drab. Size 1.75 × 1.20.

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American Crow. American Raven.

488. Crow. Corvus brachyrhynchos brachyrhynchos.

Range.–Whole of North America south of the Arctic Circle; most abundant in eastern United States; rare in many localities in the west.

Greenish white.

These birds, against which the hand of every farmer is uplifted, are very shy and cunning; as is well known, they nearly always post a sentinel in some tree top to keep watch while the rest of the flock is feeding in the field below. In the fall and winter, large numbers of them flock, and at night all roost in one piece of woods; some of the “crow roosts” are of vast extent and contain thousands of individuals.

Bluish white.

Crows nest near the tops of large trees, preferably pines, either in woods or single trees in fields. Their nests are made of sticks and lined with rootlets, and the eggs, which are laid in April or May, range from four to seven in number, are a bluish or greenish white, sparingly or very densely speckled, spotted and blotched with various shades of brown and lilac. Size 1.60 × 1.15.

488a. Florida Crow. Corvus brachyrhynchos pascuus.

Range.–Florida.

This variety has a slightly shorter tail and wings than the last.

490. Fish Crow. Corvus ossifragus.

Range.–Northwest coast from Oregon to Alaska.

This small Crow which is but 16 inches in length, is found only on the coast, where they feed upon shell fish and offal. They nest, as do the Ravens, either on ledges or in tree tops. The eggs resemble those of the common Crow, but are smaller. Size 1.55 × 1.05.

Bluish white.

489. Northwestern Crow. Corvus caurinus.

Range.–South Atlantic and Gulf coasts, north in summer to Connecticut.

From Virginia southward, this small Crow (length 16 inches) is more abundant on the coast than the common Crow which is often in company with this species. Their food consists of grain, berries, and animal matter. Their nesting habits are like those of the common Crow and the eggs are similar and have as great variations, but are smaller. Size 1.45 × 1.05.

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Clarke’s Nutcracker.

491. Clarke’s Nutcracker. Nucifraga columbiana.

Range.–Mountains of western North America from Mexico to Alaska.

Grayish blue.

The Clarke Crow, as this bird is often known, is a common resident in most of its range. The adults are grayish with black wings and central tail feathers, the tips of the primaries and outer tail feathers being white. Their tail is short and their flight slow and somewhat undulating like that of some of the Woodpeckers. Their food consists of anything edible from seeds and larvæ in the winter to insects, berries, eggs and young birds at other seasons. In the spring they retire to the tops of ranges, nearly to the limit of trees, where they build their large nests of sticks, twigs, weeds, strips of bark, and fibres matted together so as to form a soft round ball with a deeply cupped interior; the nest is located at from ten to forty feet from the ground in pine trees and the eggs are laid early before the snow begins to leave. They are three in number, grayish in color with a greenish tinge and finely spotted over the whole surface with dark brown and lavender. Size 1.30 × .90. Data.–Salt Lake Co., Utah, April 25, 1900. Nest placed in pine 40 feet up on a horizontal branch, and not visible from below. The tree was at the upper edge of a pine forest at an altitude of about 3000 feet above Salt Lake City. The nest was discovered by seeing the parent fly into the tree; the next day a nest was found with three young nearly ready to fly. Collector, W. H. Parker. This set of three eggs is in the oological collection of Mr. C. W. Crandall.

492. Pinon Jay. Cyanocephalus cyanocephalus.

Bluish white.

Range.–Western United States between the Rockies and Sierra Nevadas, and from southern British Columbia to Arizona.

This Crow-like Jay has a nearly uniform bluish plumage, and is found abundantly in the pine belts of its range. Their habits are similar to those of the Clarke Crow and the nests are similarly built at lower elevations in pines or junipers. During April or May they lay from three to five eggs of a bluish white color specked and spotted with brown. Size 1.20 × .85.

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Title: The Bird Book
Illustrating in natural colors more than seven hundred
North American birds; also several hundred photographs of
their nests and eggs

Author: Chester A. Reed

Release Date: September 15, 2009 [EBook #30000]

The Revered, Reviled Crow Clan by Howard Youth

I read an excellent article about corvids from their habitat to myths and legends about them in the May/June 2001 issue of Zoogoer. I think it is worth the read. Here is an excerpt:

For centuries, a dark specter haunted the bloody battlefields of Europe. Waiting to feast on the dead, common ravens lined up at bloody clashes between invaders and invaded, tribes and kingdoms. War-weary observers could not ignore the jet-black scavengers, with their four-foot-wide wingspreads and cross-shaped flight profiles. Ravens, not surprisingly, were branded harbingers of bad luck, or death.

Away from the carnage, common ravens (Corvus corax) also coasted into folklore, legend, and language, strongly hinting that these creatures and their 100-plus brethren in the family Corvidae are not your average birds. Two ravens, Hugin (Thought) and Munin (Memory), rode the broad shoulders of the Norse god Odin. In Inuit legend, the raven became creator and trickster. In the Bible, Noah sent not only a dove but also a raven to seek land, as did many ancient mariners. Tame ravens still stroll within the Tower of London’s walls, where for centuries they’ve been sequestered as guardians against invasion.

One reason why ravens, crows, jackdaws, rooks, magpies, treepies, choughs, nutcrackers, and jays stand out is that they have above-average brains—proportionately, they possess the largest cerebral hemispheres of the feathered set. Plucky, crafty, curious, social, vocal, and adaptable, corvids, as family members are known, are among our most familiar yet enigmatic neighbors. On all continents save Antarctica, they flourish in backyards and wilderness, although more than 20 species barely hang on within shrinking habitats. Ethiopia’s thick-billed raven (Corvus crassirostris), bigger than a red-tailed hawk, is the world’s largest songbird, while the dun-colored Hume’s ground-jay (Pseudopodoces humilis) of the Tibetan plains is the smallest family member. In between lies a broad spectrum of glossy, splashy, and plume-tailed characters.

You can read the rest of the article here.

Corvid cognition

Copyright © 2005 Elsevier Ltd All rights reserved.

Nicola Clayton and Nathan Emery

aDepartment of Experimental Psychology and Sub-department of Animal Behaviour, University of Cambridge, Cambridge, UK

Available online 7 February 2005.

Article Outline

What is a corvid? There are just over 120 species of corvids, a family of songbirds that includes the crows, ravens, rooks and jackdaws, as well as the more colourful jays, magpies and nutcrackers. Although belonging to the same order as nightingales and other birds with melodious songs (Oscines), corvids tend to be identified by their raucous calls. Little is known about corvid songs, perhaps because they are surprisingly quiet. Corvids can be found throughout the globe, except for the southern most tip of South America and the polar ice caps. In Britain, many of the common species, such as magpies and crows, steal other birds’ eggs and raid agricultural crops. They are therefore treated with disdain by many birdwatchers and farmers.

Why study intelligence in crows? Corvids have not always had such a bad press. Native Americans believed that a raven had created the earth; the Norse god, Odin, consulted two ravens Hugin (Thought) and Munin (Memory) for their wisdom; and Aesop cast corvids as the smart protagonists in many of his fables. Along with their reputation in folklore as the wisest of animals, corvids have the largest brains for their body size of any bird. Perhaps most surprisingly, the crow brain is the same relative size as the chimpanzee brain. Other aspects of corvid biology also give us clues to their intelligence. In the wild, young corvids have an extensive developmental period before they become independent from their parents. This allows them more opportunities to learn the essential skills for later life. Many corvids also live in complex social groups. For example, in the cooperatively breeding Florida scrub-jay, several closely related family members share the responsibility of raising the young with the parents. Furthermore, rooks congregate in large colonies, where juveniles associate with many non-relatives as well as kin. In both cases, this long developmental period provides increased opportunities for learning from many different group members.

Perhaps it is not surprising then that many corvids are also renowned for their innovative feeding skills. For example, Japanese crows in Sendai City have learned to crack nuts safely by dropping them onto pedestrian crossings and waiting until the traffic lights turn red before retrieving the nut’s contents. Rooks at a motorway service station in England have discovered a novel method for gaining access to food thrown in rubbish bins. Two birds cooperate in pulling up the bin liner and then either feeding from the raised food or tossing the contents onto the ground where the waiting crowd of colony mates reap the rewards.

As the crow flies… Most of the corvids that have been studied in detail hide food for the future in times of food abundance and then rely on memory to recover the food caches at a later date when food is scarce. For example, the Clark’s nutcracker is estimated to hide over 30,000 pinyon seeds in many different places during the autumn in preparation for the harsh months ahead. Laboratory experiments have shown that they have highly accurate spatial memories, which enable them to recover these caches up to 9 months later. This is no mean feat when there are so many caches to keep track of, scattered throughout the territory, and when many aspects of the landscape change so dramatically across seasons. It has been suggested that Clark’s nutcrackers rely on remembering the location of large vertical landmarks such as trees and rocks in the environment, because these landmarks are unlikely to be blown away or buried under the snow.

What do scrub-jays recall about past caching events? Although western scrub-jays do not hide as many seed caches as the nutcrackers, they are known to cache a variety of perishable foods, such as insects and fruit, as well as non-perishable nuts and seeds. In the laboratory, these birds demonstrate remarkable memories for what they have cached on a given day, and how long ago, as well as where they hid the various food items during that particular caching episode. This ability to remember the ‘what, where and when’ of specific past events is thought to be akin to human episodic memory, because it involves recalling a particular episode that has happened in the past. Until recently, this ability was thought to be unique to humans.

Avian espionage… Food-caching is a risky strategy, however, because the caches can be stolen by other birds. In addition to hiding their own food caches, corvids also play the role of thief: they watch and remember where other birds have hidden their caches and use this information to steal those caches when the owner has left the scene. When playing the role of thief, speed is of the essence and may make the difference between a successful raid and vicious attack by the owner of the food-cache. Not surprisingly, corvids also employ a number of counter strategies to reduce the risk that their own caches will be stolen by another bird. For example, they attempt to cache out of sight from potential thieves, or wait until the raider is distracted before hiding their caches, and if that is not possible, they hide caches in places that are difficult for the thief to see. When there is little option but to cache when others are around, then the birds will return to the caches once the others have left, and quickly re-hide any remaining caches in new places unbeknown to the potential raider.

Laboratory experiments have established that western scrub-jays use all these techniques to protect their caches from potential thieves, and only do so if another bird is present at the time of caching. Furthermore, they only move their caches to new hiding places if they have been thieves themselves in the past. Naı̈ve jays, even ones who have watched other birds caching but have never had the opportunity to raid those caches, do not do so. This suggests that experienced birds relate information about their previous experience of being a thief to the possibility of future theft by another bird, and adjust their caching behaviour accordingly. Using your own experience to predict another individual’s future behaviour in relation to your own – ‘putting yourself in someone else’s shoes’ – is thought to be one of the hallmarks of Theory of Mind, another ability that was thought to be uniquely human.

Cultural tool use in crows? New Caledonian crows are extraordinarily skilled at making and using tools. In the wild, they make two types of tool. The hooked tools consist of twigs that are trimmed and sculpted into a functional hook, which the crows use to poke insect larvae out of tree holes. The crows also manufacture stepped-cut Pandanus leaves, which they use in different ways for different jobs: they make rapid back and forth movements for prey under soil, yet slow deliberate movements if the prey is in a hole. These tools are consistently made to a standardized pattern and carried around on foraging expeditions. The only other animals that display this diversity and flexibility in tool use and manufacture are the great apes. Thus, chimpanzees have been observed to manufacture a range of different tools that are used for specific purposes, and different geographical populations of chimpanzees use different tools for different uses, suggesting that there may be cultural variations in tool use. Observations of the crows’ tool use in the wild also suggest similar levels of cultural complexity. For example, there is potential cumulative evolution in the complexity of stepped tools (increasing the number of steps required to make a more complex tool), analogous to minor technological innovations in humans. Crows from different geographical areas have different designs of tool, suggesting that crows may also show cultural variations in tool use.

Laboratory experiments confirm the sophisticated intellectual capabilities of these crows. One tool-using crow, called Betty, can manipulate novel man-made objects to solve a problem, such as reaching food in a bucket only accessible by using a hook to pull the bucket up. When the bent wire was stolen by another bird, Betty found a piece of straight wire that was lying on the floor, bent this wire into a hook and used it to lift up the bucket and reach the food! Betty proceeded to do this consistently. Furthermore, when given a tool box containing a variety of different tools to reach normally inaccessible food, she was able to select one of the correct length and width. So evidence of tool use and manufacture suggests that these crows can sometimes combine past experiences to produce novel solutions to problems.Feathered apes? Corvids are large-brained, social birds. They have an extensive developmental period in which they are dependent on their parents, and so have a long time-window in which to learn many different things from their parents and peers. They show a great propensity to find innovative solutions to novel problems, from the manufacture of tools to the protection of food from competitors. Furthermore, they appear to be particularly adept at predicting the future behaviour of conspecifics. These features are things they share in common with the apes. The common ancestor of mammals and birds lived over 280 million years ago, so it is hardly surprising that they have very different brains. It follows that intelligence in corvids and apes must have arisen independently in two groups with very different brains. Interestingly, the thinking part of the brain is correlated with propensity to innovate in both birds and primates, with the corvids and apes as the ‘star inventors’. So when it comes to intelligence, corvids are feathered apes.

Further reading

Where can I find out more?

R.P. Balda, A.C. Kamil and P.A. Bednekoff, Predicting cognitive capacities from natural histories: examples from four corvid species, Curr. Ornithol. 13 (1996), pp. 33–66.

N.S. Clayton, T.J. Bussey and A. Dickinson, Can animals recall the past and plan for the future?, Nat. Rev. Neurosci. 4 (2003), pp. 685–691.

N.J. Emery and N.S. Clayton, The mentality of crows: Convergent evolution of intelligence in corvids and apes, Science 306 (2004), pp. 1903–1907.

Heinrich, B. (1999). The Mind of the Raven (Harper Collins).

G.R. Hunt and R.D. Gray, Diversification and cumulative evolution in New Caledonian crow tool manufacture, Proc. Roy. Soc. Lond. B. 270 (2003), pp. 867–874.

L. Lefebvre, S.M. Reader and D. Sol, Brains, innovations and evolution in birds and primates, Brain Behav. Evol. 63 (2004), pp. 233–246.

A.A.S. Weir, J. Chappell and A. Kacelnik, Shaping of hooks in New Caledonian crows, Science 297 (2002), p. 981

“Reprinted from Current Biology, Vol 15 / Issue No 3, Author(s) Nicola Clayton and Nathan Emery, Corvid cognition, Page No. 1, Copyright 8 February 2005, with permission from Elsevier.”
Direct Link to Article click here.