The European roller (Coracias garrulus) is the only member of the roller family Coraciidae breeding in Europe. Its range extends into the Maghreb, West Asia and Central Asia. It winters in southern Africa, primarily in dry wooded savanna and bushy plains. It occurs in a wide variety of habitats, but avoids treeless plains. It usually nests in tree holes.

Taxonomy and systematics

The European roller was formally described by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his Systema Naturae under its current the binomial name Coracias garrulus. The type locality is Sweden. The generic name derives from Greek korakias referring to a type of corvid, perhaps the red-billed chough. The specific epithet garrulus is from Latin and means 'chattering' in reference to the bird's calls. Alternate English names include the blue roller, common roller, Eurasian roller, or simply roller.

A molecular phylogenetic study by Ulf Johansson and collaborators published in 2018 found that the European roller was most closely related to the Abyssinian roller (Coracias abyssinicus).

The rollers are medium-sized Old World birds of open woodland habitats. They have brightly coloured plumage and a hooked bill. Most species are found south of the Sahara. The genus Coracias contains eight species of sit-and-wait hunters.

Two subspecies are recognised:

  • C. g. garrulus <small>Linnaeus, 1758</small>: The nominate subspecies. Found in north-western Africa, southern Europe and east through north-western Iran to south-western Siberia. It is found in Iraq and southern Iran east through Kashmir and southern Kazakhstan to Xinjiang in western China.

Description

thumb|At [[Hesaraghatta Lake]]

The European roller is a stocky bird, the size of a Eurasian jay at in length with a wingspan. It is mainly blue with an orange-brown back. The subspecies C. g. semenowi is slightly paler then the nominate. to Congo and south to South Africa.

It is a bird of warm, dry, open country with scattered trees, preferring lowlands, but occurs up to in Europe and in Morocco. Oak and pine woodlands with open areas are prime breeding habitat, but farms, orchards and similar areas with mixed vegetation are also used. In Africa, a similarly wide range of dry, open land with trees is used. European rollers from eastern European populations also spend the winter period in southern Africa, but further east in Zambia, Zimbabwe and Botswana. Some population migrate through western India during August to November. The Sahel savannah region immediately south of the Sahara Desert, particularly the area around Lake Chad, appears to be important for European rollers from many populations as an autumn re-fuelling site, and Latvian and other north and north-eastern populations migrate northwards via the Arabian Peninsula in spring. Individuals from different breeding populations use distinct but overlapping winter sites; there is a correlation between the longitude of individual breeding and non-breeding sites, suggesting parallel migration. In the east, the northernmost breeders from Latvia tend to winter south of the southernmost breeders from Cyprus, indicating a pattern of 'leap-frog' migration.

Food and feeding

Rollers often perch prominently on trees, posts or overhead wires, like giant shrikes, whilst watching for the large insects, small reptiles, rodents and frogs that they eat. The diet of adult rollers is dominated by beetles, whereas nestlings mostly eat Orthoptera, such as grasshoppers and bush crickets.

Breeding

thumb|Eggs of Coracias garrulus

thumb|right|A European roller bringing food to her nest

The nest site is usually in a natural cavity in a tree or in a hole excavated by a woodpecker. It is typically located above the ground. Pairs sometimes use a cavity in rocks or buildings and may occasionally excavate a hole in a sandy bank. The hole is unlined. The clutch is 2 to 6 white smooth glossy eggs that measure . They are laid at intervals of two or occasionally three days. They are incubated by both sexes but mainly by the female starting before the clutch is completed. They hatch after 17 to 19 days. The young are cared for by both parents but usually the male passes food to the female. The nestlings fledge after 26 to 27 days. Only a single brood is raised each year, but a replacement clutch is laid if the first is lost. European rollers generally first breed when they are two years old.

The maximum age recorded from ring-recovery data is 9 years and 2 months for a bird shot in Poland.

Diseases

The European roller is a host of the Acanthocephalan intestinal parasite Moniliformis gracilis.

Conservation status

The Eurasian roller has an extensive distribution in Europe and western Asia, and its European breeding population is estimated at 159,000 to 330,000 birds. When Asian breeders are added, this gives a global total population of 277,000 to 660,000 individuals. There have been fairly rapid population declines across much of its range, so it was formerly classified as near threatened by the International Union for Conservation of Nature in 2005; it has, however, been downlisted to least concern in 2015, as population development was judged to not meet the criteria for a more urgent rating at this time.

Threats include hunting while on migration around the Mediterranean, and large numbers, possibly in the thousands, are killed for food in Oman. Agricultural practices have led to the loss of trees and hedges which provide potential nest sites and perches for hunting, and pesticides have reduced the availability of insect food.

In culture

The Steinhardt Museum of Natural History commissioned a musical project of educational songs about animals, composed and performed by Shachar Even Tzur, called "Agada Chaya" (אגדה חיה, Living Legend). One of the songs was written about the European Roller (Kahal כחל in Hebrew).

The Israel Police Airbus Helicopters H125 helicopter is called "Kahal" (the Hebrew name for European Roller).

References

Cited texts

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Abdulali, H (1936) The distribution of the Kashmir Roller (Coracias garrulus semenowi Loudon & Tschusi). Journal of the Bombay Natural History Society 38(3):622.

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  • European roller - Species text in The Atlas of Southern African Birds.
  • Oiseaux Photos
  • Ageing and sexing (PDF; 4.5 MB) by Javier Blasco-Zumeta & Gerd-Michael Heinze
  • Photos, audio and video of European roller from Cornell Lab of Ornithology's Macaulay Library