Geographic Range
Blue-bellied rollers are found in western and central Africa, from Senegal eastward
to southern Sudan.
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.
- Habitat Regions
- tropical
- terrestrial
- Terrestrial Biomes
- savanna or grassland
- forest
- scrub forest
- Other Habitat Features
- agricultural
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.
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes alike
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.
- Mating System
- monogamous
- polygynandrous (promiscuous)
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.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- oviparous
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.
- Parental Investment
- altricial
-
pre-fertilization
- provisioning
-
protecting
- female
-
pre-hatching/birth
-
provisioning
- male
- female
-
protecting
- male
- female
-
provisioning
-
pre-weaning/fledging
-
provisioning
- male
- female
-
protecting
- male
- female
-
provisioning
-
pre-independence
-
provisioning
- male
- female
-
protecting
- male
- female
-
provisioning
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.
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.
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.
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.
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.
- Primary Diet
- carnivore
- 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.
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.
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.
Additional Links
Contributors
Tanya Dewey (editor), Animal Diversity Web.
James Entwistle (author), Kalamazoo College, Ann Fraser (editor, instructor), Kalamazoo College.
- Ethiopian
-
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- terrestrial
-
Living on the ground.
- 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.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- scrub forest
-
scrub forests develop in areas that experience dry seasons.
- agricultural
-
living in landscapes dominated by human agriculture.
- 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.
- 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.
- monogamous
-
Having one mate at a time.
- polygynandrous
-
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
- 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).
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- 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.
- diurnal
-
- active during the day, 2. lasting for one day.
- motile
-
having the capacity to move from one place to another.
- migratory
-
makes seasonal movements between breeding and wintering grounds
- sedentary
-
remains in the same area
- 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
- social
-
associates with others of its species; forms social groups.
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- carnivore
-
an animal that mainly eats meat
- insectivore
-
An animal that eats mainly insects or spiders.
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
References
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 .
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 .