Western Jackdaw

Appearance

Measuring 34–39 centimetres, the Western Jackdaw is the second smallest species of corvid. Most of the plumage is a shiny black, with a purple or blue sheen on the crown, forehead and secondaries, and a green-blue sheen on the throat, primaries, and tail. The cheeks, nape and neck are light grey to greyish-silver, and the underparts slate-grey. The bill and legs are black. The iris of adults is greyish or silvery white while that of juveniles is light blue, becoming brownish before whitening at around a year of age.

In flight, Western Jackdaws are separable from other corvids by their smaller size, faster and deeper wingbeats and proportionately narrower and less fingered wing tips. They also have a shorter, thicker neck, a much shorter bill and frequently fly in tighter flocks. They can be distinguished from choughs by uniformly grey underwings and black beak and legs.

On the ground, Western Jackdaws have an upright posture and strut briskly, their short legs giving them a rapid gait. They feed with their heads held down or horizontally.

Sexes and ages are alike. Jackdaws undergo a complete moult from June to September in the western parts of their range, and a month later in the east. Immature birds have duller plumage.

The Western Jackdaw is very similar in morphology, behaviour and calls to the Daurian Jackdaw, with which its range overlaps in western Asia. Adults are readily distinguished, since the Daurian has a pied plumage, but immature birds are much more similar, both species having dark plumage and dark eyes. The Daurian tends to be darker, with a less contrasting nape, than the Western.

Within its range, the Western Jackdaw is unmistakable; its short bill and grey nape are distinguishing features. From a distance, it can be confused with a Rook, or its silhouette in flight with a pigeon or chough.

Naming

There are four recognised subspecies. All European subspecies intergrade where their populations meet. "C. m. monedula" intergrades into "C. m. soemmerringii" with the transition zone running from Finland south across the Baltic and eastern Poland to Romania and Croatia.

⤷  "C. m. monedula", the nominate subspecies, is found in eastern Europe. Its range extends across Scandinavia, from southern Finland south to Esbjerg and Haderslev in Denmark, through eastern Germany and Poland, and south across eastern central Europe to the Carpathian Mountains and north-western Romania, Vojvodina in northern Serbia, and Slovenia. It breeds in south-east Norway, southern Sweden and northern and eastern Denmark, with occasional wintering birds in England and France. It has been recorded as a rare vagrant to Spain. It has a pale nape and sides of the neck, a dark throat, and a light grey partial collar of variable extent.
⤷  "C. m. spermologus" occurs in western and central Europe, from the British Isles, Netherlands and the Rhineland in the north, though western Switzerland into Italy in the south-east, and the Iberian peninsula and Morocco in the south. It winters in the Canary Islands and Corsica. It is darker in colour than the other subspecies and lacks the whitish border at the base of the grey nape.
⤷  "C. m. soemmerringii" is found in north-eastern Europe, and north and central Asia, from the former Soviet Union to Lake Baikal and north-west Mongolia and south to Turkey, Israel and the eastern Himalayas. Its south-western limits are Serbia and southern Romania. It winters in Iran and northern India. It is distinguished by its paler nape and side of the neck creating a contrasting black crown, and lighter grey partial collar.
⤷  "C. m. cirtensis" is found in Morocco and Algeria in North Africa. It was formerly found in Tunisia. The plumage is duller and more uniform dark grey than the other subspecies, with the paler nape less distinct.The common name "jackdaw" first appears in the 16th century, and is a compound of the forename "Jack", used in animal names to signify a small form, and the native English word "daw". Formerly Jackdaws were simply called daws. Claims that the metallic "chyak" call is the origin of the "jack" part of the common name are not supported by the "Oxford English Dictionary". "Daw", first attested in the 15th century, is conjectured by the "Oxford English Dictionary" to be derived from an unattested Old English "dawe", citing cognates in Old High German "tāha", Middle High German "tāhe, tāchele", and modern German "Dahle, Dohle", and dialectal "Tach, Dähi, Däche, Dacha".
The original Old English word "cēo" gave modern English chough; Chaucer sometimes used this word, as did Shakespeare in "Hamlet" although there has been debate about which species he was referring to. This onomatopoeic name, based on the Jackdaw's call, now refers to corvids of the genus "Pyrrhocorax"; the Red-billed Chough, formerly particularly common in Cornwall, became known initially as "Cornish Chough" and then just "Chough", the name transferring from one species to the other.

English dialect names are numerous. Scottish and north England dialect has had "ka" or "kae" since the 14th century. The midlands form of this was "co" or "coo". "Caddow" is potentially a compound of "ka" and "dow", a variant of "daw". Other dialect or obsolete names include "caddesse", "cawdaw", "caddy", "chauk", "college-bird", "jackerdaw", "jacko", "ka-wattie", "chimney-sweep bird", from their nesting propensities, and "sea-crow", from their frequenting coasts. It was also frequently known quasi-nominally as "Jack"....hieroglyph snipped...

An archaic collective noun for a group of Jackdaws is a "clattering." Another term used is "train," however, in practice, most people use the more generic term "flock".

Distribution

Jackdaws are resident over a large area stretching from north-west Africa through virtually all of Europe, including the British Isles and southern Scandinavia, eastwards through central Asia to the eastern Himalayas and Lake Baikal. They are resident throughout Turkey, the Caucasus, Iran, Iraq, Afghanistan, Pakistan and north-west India. The species has a large range, with an estimated global extent of between 1,000,000 and 10,000,000 km². It has a large global population, with an estimated 10 to 29 million individuals in Europe.

Jackdaws are mostly resident, but the northern and eastern populations are more migratory, relocating to wintering areas between September and November and returning between February and early May. Their range expands northwards into Russia to Siberia during summer, and retracts in winter. They are vagrants to the Faroe Islands, particularly in the winter and spring, and occasionally to Iceland. Jackdaw populations congregate over winter in the Ural Valley in north-western Kazakhstan, north Caspian, and the Tian Shan region of western China. They are winter visitors to the Quetta Valley in western Pakistan. They are winter vagrants to Lebanon, first recorded there in 1962. In Syria they are winter vagrants and rare residents with some confirmed breeding taking place. Jackdaws are regionally extinct in Malta and Tunisia. The "soemmerringii" subspecies occurs in south-central Siberia and extreme north-west China and is accidental to Hokkaido, Japan.

A small number of Western Jackdaws reached the north-east of North America in the 1980s, presumably ship-assisted, and have been found from Atlantic Canada to Pennsylvania. They have also occurred as vagrants in Gibraltar, Mauritania, and Saint Pierre and Miquelon. A Jackdaw is reported to have once been seen in Egypt.

Western Jackdaws inhabit wooded steppes, pasture and cultivated land, coastal cliffs, and villages and towns. They thrive as forested areas are cleared and converted to fields and open areas. Habitats with a mix of large trees, buildings and open ground are preferred; the Jackdaw leaves open fields to the Rook and more wooded areas to the Common Jay. Along with other corvids such as the Rook, Common Raven, and Hooded Crow, the Jackdaw spends the European winter in urban parks. Jackdaw populations measured in three urban parks in Warsaw show increases from October to December, possibly due to birds migrating there from areas further north. The same data from Warsaw, collected from 1977 to 2003, showed that the wintering Jackdaw population had increased four-fold. The cause of the increase is unknown, but a reduction in the number of Rooks may have benefited the Jackdaw locally, or Rooks overwintering in Belarus may have caused Jackdaws to relocate to Warsaw.

Censuses of bird populations in marginal uplands in Britain show that Jackdaws greatly increased in numbers between the 1970s and 2010, although this increase may be related to recovery from previous periods of persecution. The UK population was estimated at 2.5 million individuals in 1998, up from 780,000 in 1970.

Behavior

Jackdaws are highly gregarious and are generally seen in small to large flocks, though males and females pair-bond for life and pairs stay together within flocks. There is an increase in flock size in autumn and the birds congregate at dusk for communal roosting, with up to several thousand Jackdaws gathering at one site. At Uppsala, in Sweden, 40,000 Jackdaws have been recorded at a single winter roost and mated pairs often settle together for the night. Jackdaws become sexually mature in their second year, and there is little evidence for divorce or extra-pair coupling, even after multiple instances of reproductive failure. Genetic analysis of pairs and offspring shows no evidence of extra-pair coupling. Some pairs do separate in the first few months, but almost all pairings of over six months' duration are lifelong, ending only when a partner dies. Widowed or separated birds fare badly, often ousted from nests or territories and unable to rear broods alone.

Jackdaws frequently congregate with Hooded Crows, or Rooks, the latter particularly when migrating or roosting. They have been recorded foraging with the Common Starling, Northern Lapwing or Common Gull for food in northwestern England.

Jackdaws are generally wary of people in the forest or countryside, but much tamer in urban areas. Like Magpies, they are known to pick up shiny objects such as jewellery to hoard in nests. John Gay in his "Beggar's Opera" notes that "A covetous fellow, like a jackdaw, steals what he was never made to enjoy, for the sake of hiding it", and in Tobias Smollett's "The Expedition of Humphry Clinker", a scathing character assassination by Mr Bramble runs, "He is ungracious as a hog, greedy as a vulture, and thievish as a jackdaw." Al Stewart's song, "Midas Shadow", contains the line, "Conquistador in search of gold for all the jackdaw reasons".

Jackdaw flocks are targets of coordinated hunting by pairs of Lanner Falcons, although birds in larger flocks are more able to elude the predators.

Wind tunnel experiments show the preferred gliding speed to be between 6 and 11 metres per second, and that the wingspan decreases as the Jackdaw flies faster.The Jackdaw is a highly sociable species outside of the breeding season, occurring in flocks that can contain hundreds of birds.

In his book, "King Solomon's Ring", Konrad Lorenz records and analyses the complex social interactions in Jackdaw flocks. Lorenz studied Jackdaws living near his house in Altenberg, Austria, ringing them for identification, and caging them in the winter to prevent their annual migration. He found that Jackdaws have a linear hierarchical group structure with higher-ranked birds dominating lower-ranked birds, and that pair-bonded birds share the same rank.

Jackdaws mate for life, pairing before sexual maturity. Young males establish individual status before pairing with females. Upon pairing the female assumes the same social position as her partner. Unmated females are the lowest members in the pecking order, and are the last to have access to food and shelter.

Lorenz noted a case in which a male, absent during the dominance struggles and pair bondings, returned to the flock, became the dominant male, and chose one of two unpaired females for a mate. This female immediately assumed a dominant position in the social hierarchy and demonstrated this by pecking others. According to Lorenz, the most significant factor of social behaviour was the immediate and intuitive grasp of the new hierarchy by each of the Jackdaws in the flock.

Jackdaws have been observed sharing food and objects. The active giving of food in birds is found mainly in the context of parental care and courtship. Jackdaws show much higher levels of active giving than documented for chimpanzees. The function of this behaviour is not fully understood, although it has been found to be detached from nutrition and compatible with hypotheses of mutualism, reciprocity and harassment avoidance. It has been proposed that the sharing may be motivated by prestige enhancement.

The Jackdaw and the White-throated Magpie-Jay are the only two non-caching corvids to display the cognitive ability to find test food items when set exclusion tasks.

Occasionally a sick or injured bird is mobbed until it is killed.

Habitat

Jackdaws are resident over a large area stretching from north-west Africa through virtually all of Europe, including the British Isles and southern Scandinavia, eastwards through central Asia to the eastern Himalayas and Lake Baikal. They are resident throughout Turkey, the Caucasus, Iran, Iraq, Afghanistan, Pakistan and north-west India. The species has a large range, with an estimated global extent of between 1,000,000 and 10,000,000 km². It has a large global population, with an estimated 10 to 29 million individuals in Europe.

Jackdaws are mostly resident, but the northern and eastern populations are more migratory, relocating to wintering areas between September and November and returning between February and early May. Their range expands northwards into Russia to Siberia during summer, and retracts in winter. They are vagrants to the Faroe Islands, particularly in the winter and spring, and occasionally to Iceland. Jackdaw populations congregate over winter in the Ural Valley in north-western Kazakhstan, north Caspian, and the Tian Shan region of western China. They are winter visitors to the Quetta Valley in western Pakistan. They are winter vagrants to Lebanon, first recorded there in 1962. In Syria they are winter vagrants and rare residents with some confirmed breeding taking place. Jackdaws are regionally extinct in Malta and Tunisia. The "soemmerringii" subspecies occurs in south-central Siberia and extreme north-west China and is accidental to Hokkaido, Japan.

A small number of Western Jackdaws reached the north-east of North America in the 1980s, presumably ship-assisted, and have been found from Atlantic Canada to Pennsylvania. They have also occurred as vagrants in Gibraltar, Mauritania, and Saint Pierre and Miquelon. A Jackdaw is reported to have once been seen in Egypt.

Western Jackdaws inhabit wooded steppes, pasture and cultivated land, coastal cliffs, and villages and towns. They thrive as forested areas are cleared and converted to fields and open areas. Habitats with a mix of large trees, buildings and open ground are preferred; the Jackdaw leaves open fields to the Rook and more wooded areas to the Common Jay. Along with other corvids such as the Rook, Common Raven, and Hooded Crow, the Jackdaw spends the European winter in urban parks. Jackdaw populations measured in three urban parks in Warsaw show increases from October to December, possibly due to birds migrating there from areas further north. The same data from Warsaw, collected from 1977 to 2003, showed that the wintering Jackdaw population had increased four-fold. The cause of the increase is unknown, but a reduction in the number of Rooks may have benefited the Jackdaw locally, or Rooks overwintering in Belarus may have caused Jackdaws to relocate to Warsaw.

Censuses of bird populations in marginal uplands in Britain show that Jackdaws greatly increased in numbers between the 1970s and 2010, although this increase may be related to recovery from previous periods of persecution. The UK population was estimated at 2.5 million individuals in 1998, up from 780,000 in 1970.

Reproduction

Jackdaws usually breed in colonies with monogamous pairs collaborating to find a nest site which they then defend from other pairs and from predators during most of the year. They nest in cavities in trees or cliffs, in ruined or occupied buildings and in chimneys, the common feature being a sheltered site for the nest. The availability of suitable sites influences their presence in a locale. They may use church steeples for nesting, a fact reported in verse by 18th century English poet William Cowper:

"A great frequenter of the church,"
"Where, bishoplike, he finds a perch,"
"And dormitory too."

Nests are usually constructed by a mated pair improving the crevice by dropping sticks into it; the nest is then built on top of the platform formed. This behaviour has led to the blocking of chimneys and even resulted in nests crashing down into fireplaces, sometimes with birds still on them. Nest platforms can attain a great size — John Mason Neale notes that a "Clerk was allowed by the Churchwarden to have for his own use all that the caddows had brought into the Tower: and he took home, at one time, two cart-loads of good firewood, besides a great quantity of rubbish which he threw away."

Gilbert White, in his "The Natural History of Selborne", notes that Jackdaws used to nest in crevices beneath the lintels of Stonehenge, and describes an example of the bird using a rabbit burrow for nesting. The Jackdaw has been recorded outcompeting the Tawny Owl for nest sites in the Netherlands. They use old Black Woodpecker nest sites.

Nests are lined with hair, rags, bark, soil, and many other materials. The eggs are a lighter colour than those of other corvids, being smooth, glossy pale blue speckled with dark brown, measuring approximately 36 x  26 mm. Clutches usually contain 4 or 5 eggs, although a Slovakian study yielded clutch sizes of anywhere from 2 to 9 eggs. The eggs are incubated by the female for 17–18 days until hatching as naked altricial chicks, which are completely dependent on the adults for food. They fledge after 28–35 days, and the parents continue to feed them for another four weeks or so.

Jackdaws hatch asynchronously and incubation begins before clutch completion, which often leads to the death of the last-hatched young. Any chick that dies early in the nest keeps the parental investment to a minimum and this means the brood size comes to fit the available food supply.

The Great Spotted Cuckoo has been recorded as a brood parasite of the Jackdaw, depositing its eggs in their nests, in Spain and Israel. The European pine marten raids nests in Sweden, but is less successful in nests in colonies.

Food

The Jackdaw forages in open areas and on the ground, but does take some food in trees. Rubbish tips, bins, urban streets and gardens are also visited, more often early in the morning when there are fewer people about. Jackdaws employ various feeding methods, such as jumping, pecking, clod-turning and scattering, probing the soil, and occasionally, digging. Flies around cow pats are caught by jumping from the ground or at times by dropping vertically a few metres onto the cow pat. Earthworms are not usually extracted from the ground by Jackdaws but are eaten from freshly ploughed soil. Compared with other corvids, the Jackdaw spends more time exploring and turning over objects with its bill. A straighter and less downturned bill, with increased binocular vision, are advantageous for this foraging strategy, these being more developed in this species than in other corvids.

The Jackdaw tends to feed upon small invertebrates up to 18 millimetres in length found above ground, including larvae and pupae of Curculionidae, Coleoptera, Diptera, and Lepidoptera species. Snails, spiders and various insects also make up part of their animal diet. The Jackdaw will also eat small rodents, eggs and chicks, as well as carrion such as roadkill. Vegetable items consumed include farm grains, seeds of weeds, elderberries, acorns and various cultivated fruits. Examination of the gizzards of Jackdaws shot in Cyprus in spring and summer revealed a diet of cereals and insects. A study in southern Spain examining Jackdaw pellets found they contained significant amounts of silicaceous and calcareous grit to aid digestion of vegetable food and supply dietary calcium.

Opportunistic and highly adaptable, the Jackdaw varies its diet markedly depending on available food sources. They have been recorded raiding the nests of the Skylark, Manx Shearwater, Razorbill, Common Murre, Grey Heron, Rock Pigeon, and Eurasian Collared Dove. A field study of a large city dump on the outskirts of León in northwestern Spain showed Jackdaws forage there in the early morning and at dusk, and engage in some degree of kleptoparasitism, stealing food from each other.

Jackdaws practice active food sharing, where the initiative for the transfer lies with the donor, with a number of individuals, regardless of sex and kinship. They also share more of a preferred food than a less preferred food.

The Saker Falcon has been reported stealing food from Jackdaws on powerlines in Vojvodina in Serbia.

Cultural

Ancient Greek authors tell how a Jackdaw, being a narcissistic creature, may be caught with a dish of oil into which it falls while looking at its own reflection. The Roman poet Ovid saw Jackdaws as harbingers of rain. In Greek legend, Princess Arne was bribed with gold by King Minos of Crete, and was punished for her greed by being transformed into an equally avaricious Jackdaw, who still seeks shiny things. In Aesop's Fables, the Jackdaw embodies stupidity in one tale, by starving while waiting for figs on a fig tree to ripen, and vanity in another in which the daw sought to become king of the birds with borrowed feathers, but was shamed when they fell off. Pliny notes how the Thessalians, Illyrians and Lemnians cherished Jackdaws for destroying grasshoppers' eggs. The Veneti are fabled to have bribed the Jackdaws to spare their crops. An ancient Greek and Roman adage runs "The swans will sing when the jackdaws are silent", meaning that educated or wise people will speak only after the foolish have become quiet.

In some cultures, a Jackdaw on the roof is said to predict a new arrival; alternatively, a Jackdaw settling on the roof of a house or flying down a chimney is an omen of death, and coming across one is considered a bad omen. A Jackdaw standing on the vanes of a cathedral tower is said to foretell rain. The 12th century historian William of Malmesbury records the story of a woman who, upon hearing a Jackdaw chattering "more loudly than usual," grew pale and became fearful of suffering a "dreadful calamity", and that "while yet speaking, the messenger of her misfortunes arrived".

"The Ingoldsby Legends" contains a poem by Richard Harris Barham named "The Jackdaw of Rheims". At a banquet, while the cardinal is having his hands ceremoniously washed, his turquoise ring is stolen. Enraged, the cardinal puts a dreadful curse on the thief. To everybody's amazement, nobody present is affected by the curse, but a Jackdaw flutters down, emaciated, bald, dishevelled and lame. It leads them to its nest in the belfry where the ring is discovered. The cardinal is delighted at the return of his ring and lifts the curse and when some time later the Jackdaw dies, canonises him, giving him the name "Jim Crow".

Vincent Bourne, a master of Westminster School, wrote a Latin poem on the Jackdaw, which was translated into English by William Cowper, and forms the opening reference to a tale by George Augustus Henry Sala about a royal wedding viewed from the point of view of a Jackdaw.

Czech superstition formerly held that if Jackdaws are seen quarrelling, war will follow, and that Jackdaws will not build nests at Sázava having been banished by Saint Procopius.

In his 1979 "The Book of Laughter and Forgetting", Milan Kundera notes that Franz Kafka's father Hermann had a sign in front of his shop with a Jackdaw painted next to his name, since "kavka" means "Jackdaw" in Czech.

The Jackdaw features on the Ukrainian town of Halych's coat of arms, the town's name allegedly derived from the East Slavic word for the bird.

The sentence, 'Jackdaws love my big sphinx of quartz', contains all the letters of the alphabet and can be used to check keyboards in the same way as 'the quick brown fox jumps over the lazy dog'.