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Coracias cyanogasterblue-bellied roller

By James Entwistle

Geographic Range

Blue-bellied rollers are found in western and central Africa, from Senegal eastward to southern Sudan. (Mackworth-Praed and Grant, 1970)

Habitat

Blue-bellied rollers live in wooded savanna, tree plantations, forest edges, recently burned land, and forests near marshes. These savanna areas are often forest edges, and are rarely more than several tens of meters above sea level. (Cave and MacDonald, 1955; Fry, et al., 1988; Moynihan, 1990)

  • Average elevation
    50 m
    164.04 ft

Physical Description

Blue-bellied rollers are small birds with relatively large heads. They have heavy, downward-curved beaks and short legs to fit their stocky bodies. Blue-bellied rollers have cream-colored heads and chests, with pale-blue bellies and dark blue or dark green wings. These birds have a brownish-black mantle and scapulars with streaks of green. Blue-bellied rollers have azure-blue tails, which are slightly forked. They have an average wingspan of 359 mm, with each wing measuring an average length of 183 mm. Mass ranges from about 110 g to 150 g, with an average mass of 142 g. Blue-bellied rollers are generally about 280 mm to 300 mm in total length. Juveniles are typically smaller than adults, with duller coloration and a shorter tail. There are no known polymorphisms or subspecies. (Cave and MacDonald, 1955; Zoo, 2003/2006; Cave and MacDonald, 1955; Fry, et al., 1988; Zoo, 2003/2006)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    110 to 150 g
    3.88 to 5.29 oz
  • Average mass
    142 g
    5.00 oz
  • Range length
    280 to 300 mm
    11.02 to 11.81 in
  • Average wingspan
    359 mm
    14.13 in

Reproduction

Blue-bellied rollers undergo courtship when specific rollers call loudly and raucously to attract their mates. Blue-bellied rollers, along with other "rollers" (Coraciidae), got their name from their unique courtship behaviors, in which they roll back and forth in the sky, tumbling to the ground, while calling loudly and raucously. Blue-bellied rollers are territorial and attack any birds that approach their nests. Males and females engage in a fast chasing flight, described above. One male copulates with one or two females. Blue-bellied rollers are sometimes monogamous and sometimes promiscuous. Male blue-bellied rollers have been known to copulate with two different females in intervals of only ten minutes, up to three males may copulate with the same female. (Fry, et al., 1988; Moynihan, 1990; Zoo, 2003/2006)

Blue-bellied rollers breed in the spring and summer months, from April to July. They generally lay two or three eggs per season. Both parents incubate the eggs for about 18 to 20 days. Both parents feed the nestlings for about 30 days after hatching and for up to twenty days after fledging. Blue-bellied rollers typically become independent after about forty days. There is no information available regarding the age of sexual maturity. (Ali, 2005/2006; Bannerman, 1953; Fry, et al., 1988)

  • Breeding interval
    Blue-bellied rollers usually breed once yearly.
  • Breeding season
    Blue-bellied rollers typically breed from April to July.
  • Range eggs per season
    2 to 3
  • Range time to hatching
    22 to 24 days
  • Average fledging age
    4 weeks
  • Average time to independence
    40 days

Blue-bellied rollers feed their young by means of regurgitation. Both parents incubate eggs for 18 to 20 days, although most incubation is done by the female parent. Both parents feed nestlings for 30 days and for up to 20 days after fledging. (Ali, 2005/2006; Fry, et al., 1988; Zoo, 2003/2006)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male
      • female

Lifespan/Longevity

There is no available information on the specific lifespan of blue-bellied rollers, but there is information available pertaining to other species of rollers. European rollers (Coracias garrulus) live for approximately 8.9 years in captivity. (Mackworth-Praed and Grant, 1970)

Behavior

Blue-bellied rollers are a social species, usually living in groups of three to seven birds, although groups of up to twenty birds have been recorded. Some blue-bellied rollers migrate during the wet season (in winter). Blue-bellied rollers are known for their tendencies to sit in trees at about ten meters off the ground and dive to the forest floor for insects. Blue-bellied rollers flock to forest and savanna fires, where they wait outside the fire and feed on insects fleeing the flames. (Fry, et al., 1988; Zoo, 2003/2006)

  • Average territory size
    10,000 m^2

Home Range

The mean density of blue-bellied rollers in savanna habitats is 414 adults per 19.5 square kilometers. Pairs and small groups of blue-bellied rollers often defend territories as large as 10,000 square meters. (Moynihan, 1990)

Communication and Perception

Social interaction and communication among blue-bellied rollers consists of calling, flying together, and chasing. These activities are used to show territoriality, maintain group unity, and initiate courtship. (Bannerman, 1953; Fry, et al., 1988; Moynihan, 1990; Bannerman, 1953; Fry, et al., 1988; Moynihan, 1990)

Food Habits

Blue-bellied rollers generally feed on large invertebrates such as beetles, grasshoppers, winged ants and termites. Blue-bellied rollers also feed on some small vertebrates, including colubrid snakes. They also eat oil-palm fruits. (Fry, et al., 1988; Zoo, 2003/2006)

  • Animal Foods
  • reptiles
  • insects
  • terrestrial non-insect arthropods
  • terrestrial worms
  • Plant Foods
  • fruit

Predation

Blue-bellied rollers are not heavily preyed on. In open savanna environments, blue-bellied rollers are typically large, powerful, and agile enough to escape most predators, such as carnivorous mammals and rodents, snakes, and hawks. Eggs, nestlings, and fledglings are most vulnerable. Blue-bellied rollers are less aggressive toward potential predators than they are to other animals that invade their territory. (Moynihan, 1990)

Ecosystem Roles

Blue-bellied rollers act as predators towards large insect populations in central and western Africa. Because of their territorial habits they may benefit the trees they inhabit for shelter by warding off other animals that attempt to feed on the leaves. (Fry, et al., 1988; Moynihan, 1990; Zoo, 2003/2006)

Economic Importance for Humans: Positive

Blue-bellied rollers are well-adapted to living in regions dominated by agriculture. They probably play a key role in pest control for farmers in these areas by eating insects which may otherwise feed on crops.

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

There are no known adverse effects of blue-bellied rollers on humans.

Conservation Status

Blue-bellied rollers have been placed in the lower risk/least concern category in the IUCN Red List in 1988, 1994 and 2000. These birds are not currently in any danger of extinction. ("IUCN Redlist of Threatened Species", 2001)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

James Entwistle (author), Kalamazoo College, Ann Fraser (editor, instructor), Kalamazoo College.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

migratory

makes seasonal movements between breeding and wintering grounds

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

References

2001. "IUCN Redlist of Threatened Species" (On-line). IUCN Redlist of Threatened Species: Coracias cyanogaster . Accessed November 08, 2006 at http://www.iucnredlist.org/search/details.php/47672/summ.

Ali, D. 2005/2006. "Coraciidae" (On-line). birding.in. Accessed November 10, 2006 at http://www.birding.in/birds/Coraciiformes/coraciidae.htm.

Bannerman, D. 1953. The Birds of West and Equatorial Africa. Birmingham, Great Britain: The Knyoch Press.

Cave, C., J. MacDonald. 1955. Birds of the Sudan. 56 Annandale Street, Edinburgh, Great Britain: J. & J. Gray.

Fry, C., S. Keith, E. Urban. 1988. The Birds of Africa. 24/28 Oval Road, London, England: Harcourt Brace Jovanovich.

Mackworth-Praed, C., C. Grant. 1970. Birds of West Central and Western Africa. Norwich, Great Britain: Jarrold & Sons Ltd.

Max Planck Institute, 2002. "Longevity Records" (On-line). Longevity Records: Life Spans of Mammals, Birds, Amphibians, Reptiles, and Fish. Accessed November 12, 2006 at http://www.demogr.mpg.de/longevityrecords/0303.htm.

Moynihan, M. 1990. Social, sexual, and pseudosexual behavior of the blue-bellied roller, Coracias cyanogaster: the consequences of crowding or concentration. Smithsonian Contributions to Zoology, Number 491: 1-23.

Zoo, H. 2003/2006. "Blue-bellied roller" (On-line). Our World of Animals - Animal Information. Accessed October 08, 2006 at http://www.houstonzoo.org/Animal/viewAnimalDetail.asp?scriptaction=showanimal&Animal_Preview_Flag=0&animal_ID=84.

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