Coloeus monedula monedula Linnaeus, 1758
Coloeus monedula monedula Linnaeus, 1758
Syn. : Corvus monedula Linnaeus, 1758
Common names: Western Jackdaw, Eurasian jackdaw [En], Choucas des tours, Corbeau choucas, Corneille des clochers [Fr], Kauw [Nl], Dohle [De], Taccola eurasiatica [It], Grajilla occidental [Es], Κάργια [Gr], Küçük karga [Tu]
IUCN Status: LC (Least Concern)
Tubize, BRABANT ● Belgium
Description: Measuring 34–39 centimetres in length, the western jackdaw is a black-plumaged bird with a grey nape and distinctive pale-grey irises.
Most of the plumage is a shiny black, with a purple (in subspecies monedula and spermologus) or blue (in subspecies cirtensis and soemmerringii) 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 are slate-grey. The legs are black, as is the short stout bill, the length of which is about 75% of the length of the rest of the head. There are rictal bristles covering around 40% of the maxilla and 25% of the lower mandible. The irises of adults are greyish or silvery white while those of juveniles are light blue, becoming brownish before whitening at around one year of age. The sexes look alike.
Immature birds have duller and less demarcated plumage.
There are four recognised subspecies of the western jackdaw. All European subspecies intergrade where their populations meet.
• C. m. monedula Linnaeus, 1758 – Eastern Europe, across Scandinavia through eastern Germany and Poland, and south across eastern central Europe to the Carpathian Mountains and north-western Romania, northern Serbia, and Slovenia. 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 Vieillot, 1817 – Western and central Europe from the British Isles, Netherlands and the Rhineland in the north, through 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 Fischer, 1811 – 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 (Kashmir). It is distinguished by the nape and the sides of the neck being paler, creating a contrasting black crown and lighter grey part collar.
• C. m. cirtensis Rothschild and Hartert, 1912 – Morocco and Algeria. The plumage is duller and more uniformly dark grey than the other subspecies, with the paler nape less distinct.
Biology: Highly gregarious, western jackdaws are generally seen in flocks of varying sizes, though males and females pair-bond for life and pairs stay together within flocks.
The western jackdaw tends to feed on small invertebrates up to 18 millimetres (0.71 in) in length that are found above ground, including various species of beetle (particularly cockchafers of the genus Melolontha, and weevil larvae and pupae), Diptera, and Lepidoptera species, as well as snails and spiders. Also eaten are small rodents, bats, the eggs and chicks of birds, and carrion such as roadkill. Vegetable items consumed include farm grains (barley, wheat and oats), weed seeds, elderberries, acorns, and various cultivated fruits. Opportunistic and highly adaptable, the western jackdaw varies its diet markedly depending on available food sources.
Western jackdaws practice active food sharing, mainly in the context of parental care and courtship. Western jackdaws show much higher levels of active giving than has been documented for other species, including chimpanzees. The function of this behaviour is not fully understood, though it has been found to be detached from nutrition and compatible with hypotheses of mutualism, reciprocity and harassment avoidance. It has also been proposed that food sharing may be motivated by prestige enhancement.
Western jackdaws become sexually mature in their second year. Genetic analysis of pairs and offspring shows no evidence of extra-pair copulation and there is little evidence for couple separation even after multiple instances of reproductive failure. Almost all pairings of over six months' duration are lifelong, ending only when a partner dies.
Western jackdaws usually breed in colonies with pairs collaborating to find a nest site, which they then defend from other pairs and predators during most of the year. They nest in cavities in trees or cliffs, in ruined or occupied buildings and in chimneys, church steeples, the common feature being a sheltered site for the nest.
Nests are lined with hair, wool, dead grass and many other materials. Clutches usually contain 4 or 5 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.
Habitat: Western jackdaws inhabit wooded steppes, pastures, cultivated land, coastal cliffs, and towns. They thrive when forested areas are cleared and converted to fields and open areas. Habitats with a mix of large trees, buildings, and open ground are preferred; open fields are left to the rook, and more wooded areas to the Eurasian jay (Garrulus glandarius). Along with other corvids such as the rook, common raven (Corvus corax), and hooded crow (C. cornix), some western jackdaws spend the winter in urban parks.
Distribution: The western jackdaw is found from north-west Africa through all of Europe, except for the extreme north, and eastwards through central Asia to the eastern Himalayas and Lake Baikal. To the east, it occurs throughout Turkey, the Caucasus, Iran, Iraq, Afghanistan, Pakistan, and north-west India.
Wikipedia, Western jackdaw