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Bycanistes subcylindricusgrey-cheeked hornbill

By Abby Velting

Geographic Range

Black-and-white-casqued hornbills are found in forests and savannas throughout West and Central Africa. The subspecies Bycanistes s. subcylindricus ranges from Sierra Leone and northeast Liberia across the Ivory Coast to western Nigeria, and the subspecies, B. s. subquadratus, ranges from eastern Nigeria, Cameroon, and the Central African Republic to Sudan, Zaire, Uganda, southwest Kenya, and northwest Tanzania (del Hoyo et al., 2001). An isolated population of B. s. subquadratus also exists in Angola (Lewis and Pomeroy 1989). (del Hoyo, et al., 2001; Lewis and Pomeroy, 1989)

Habitat

Black-and-white-casqued hornbills are most commonly found in subtropical/tropical lowland and montane forests, where they reach altitudes of 2,600 m (del Hoyo et al., 2001; BirdLife International 2008). This species is less frequently seen in artificial landscapes such as plantations or urban areas, heavily degraded forests and dry savannas (BirdLife International 2008). ("BirdLife International Species factsheet: Bycanistes subcylindricus.", 2008; del Hoyo, et al., 2001)

  • Range elevation
    2,600 (high) m
    ft

Physical Description

Black-and-white-casqued hornbills are fairly large, mainly black hornbills with white lower backs and rumps, upper and under tail-coverts, thighs, bellies, and vents. The central pair of rectrices is all black, while the rest of the tail feathers are black-based and extensively white distally. The secondaries and inner primaries are mostly white with black bases. This species has grey-tipped facial feathering, which gave rise to another common name, gray-cheeked hornbills. (del Hoyo, et al., 2001; Kalina, 1988; Kemp, 1995)

Males have red eyes, blackish facial skin and a dark brown bill with a high-ridged, laterally flattened casque which has a broad cream-colored base. Casque pattern varies individually sufficiently to aid scientists in individual recognition (Kalina 1988). Females have a much smaller all-blackish bill, and the casque is reduced to a lower, rounded ridge on the basal upper mandible. Females have pink facial skin and brown eyes. Males are larger than females, weighing between 1,078 and 1,525 g, while females weigh between 1,000 and 1,250g. (del Hoyo, et al., 2001; Kemp, 1995)

Juveniles emerging from the nest have small bills lacking casques (Kilham 1956; del Hoyo et al., 2001). Birds less than a year of age have brown feathers on the forehead and around the base of the bill (Kalina 1988; Kemp 1995). Subadults have a high degree of vascularization in the area of the future casque. The facial feathers turn from brown to grey by 10 months of age (Kemp 1995). (del Hoyo, et al., 2001; Kalina, 1988; Kemp, 1995; Kilham, 1956)

The subspecies B. s. subquadratus is larger than B. s. subcylindricus and has more cream coloring along the casque and more white below (del Hoyo et al., 2001). (del Hoyo, et al., 2001)

  • Sexual Dimorphism
  • male larger
  • sexes colored or patterned differently
  • male more colorful
  • sexes shaped differently
  • ornamentation
  • Range mass
    1,000 to 1,525 g
    to oz
  • Range length
    60 to 70 cm
    23.62 to 27.56 in
  • Range wingspan
    284 to 378 mm
    11.18 to 14.88 in

Reproduction

Black-and-white-casqued hornbills are monogamous, breeding seasonally from January to May in Central Africa and August to March in eastern Africa. Their breeding season coincides with local rainy seasons, so they can take full advantage of the abundance of fruit and arthropods at this time (del Hoyo et al., 2001; Kalina 1988). (del Hoyo, et al., 2001; Kalina, 1988)

Bycanistes subcylindricus individuals commonly nest in naturally formed cavities 9 to 30 m high in large (>3 m circumference) rainforest trees. Due to the rarity of these nesting cavities, there is a high degree of intraspecific competition for nesting sites. In order to protect their nest, pairs seal the cavity with mud pellets collected by the male. Inside, the female lays a clutch of 2 eggs, which are typically 49.3 x 37.4 cm and white in color with pitted shells (Kemp 1995). The eggs are incubated for 42 days while the male delivers food to the female hourly through a small slit, regurgitating numerous fruits, mammals, and insects. The male can bring up to 200 fruits per visit. Usually only one offspring is reared, with the chick from the second-laid egg dying of starvation. Newly hatched chicks have pink skin and open their eyes at 20 days of age. The offspring fledge in 70 to 79 days and can feed themselves by 40 to 72 days after fledging (del Hoyo et al., 2001; Kalina 1988; Kemp 1995). (del Hoyo, et al., 2001; Kalina, 1988; Kemp, 1995)

  • Breeding interval
    Time between breeding efforts is not known.
  • Breeding season
    Breeding occurs during wet seasons, but can occur throughout the year.
  • Average eggs per season
    2
  • Average time to hatching
    42 days
  • Range fledging age
    70 to 79 days
  • Range time to independence
    101 to 139 days
  • Average age at sexual or reproductive maturity (male)
    3 years

Both male and female black-and-white-casqued hornbills care for, protect, and provide for their offspring during the nesting and fledgling stages.

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

Lifespan/Longevity

Black-and-white-casqued hornbills have been known to live up to 31.8 years in captivity. (Kemp, 1995)

  • Range lifespan
    Status: captivity
    31.8 (high) years

Behavior

Black-and-white-casqued hornbills are active during the day. They are nomadic during the dry, non-breeding season and actively defends their nesting area when breeding. (Kalina, 1988)

Home Range

Movements and dispersion of these hornbills vary seasonally. In the few months prior to and during breeding, pairs actively defend their nesting tree. They make repetitive “long-calls” and “high-pitched screams” while perched atop the tree. All other approaching hornbills are chased away. During the dry season, when this species does not nest, they are nomadic, sometimes traveling over 6 km to visit fruiting trees. (Kalina, 1988)

Communication and Perception

Black-and-white-casqued hornbills are quite vocal, with a large repertoire of calls, one of which can be heard from a distance of 2km (Kalina 1988). Calls differ between the two subspecies. Bycanistes s. subcylindricus makes mournful hooting notes, whereas B. s. subquadratus makes quacking notes uttered at a higher pitch and frequency (Kalina 1988; Kemp 1995) (Kalina, 1988; Kemp, 1995)

Food Habits

Black-and-white-casqued hornbills are mainly frugivorous, with fruit comprising 90% of their diet, 56% belonging to Ficus species. They forage by hopping from branch to branch in the rainforest canopy and reaching for fruit with the tip of the bill, which they then swallow whole. This species is known to consume over 41 plant genera (Kalina 1988; del Hoyo et al., 2001). (del Hoyo, et al., 2001; Kalina, 1988)

Black-and-white-casqued hornbills also consume birds, eggs, insects, bats, snails, lizards, mollusks, other small animal prey, mosses, lichens, and fungi. The carnivorous component of the diet is increased while breeding. These hornbills, alone or in flocks, occasionally raid weaver colonies (Ploceidae) or Egyptian rousette bat (Rousettus aegyptiacus) roosts and have also been reported feeding on various species of galagos (Galago). They are frequently seen foraging alongside monkeys or squirrels. (del Hoyo, et al., 2001; Kalina, 1988; Kemp, 1995; Kilham, 1956)

  • Animal Foods
  • birds
  • mammals
  • reptiles
  • eggs
  • insects
  • mollusks
  • Plant Foods
  • fruit
  • bryophytes
  • lichens
  • Other Foods
  • fungus

Predation

Carnivores, apes, monkeys, snakes, raptors, and humans all prey on these hornbills. The placement of their nests high off the ground helps reduce much nest predation by carnivores, but raptors such as crowned eagles (Harpyhaliaetus coronatus) commonly prey on them (Kalina 1988). (Kalina, 1988)

Ecosystem Roles

Black-and-white-casqued hornbills mediate seed dispersal of rainforest trees, by defecating or regurgitating seeds (Kalina 1988). (Kalina, 1988)

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

Like all hornbills, black-and-white-casqued hornbills. with their unusual behaviors and impressive casques are interesting to many different groups of people, and therefore contribute to the success of ecotourism in Africa. They help to regenerate native forest through seed dispersal. (Kalina, 1988)

  • Positive Impacts
  • ecotourism
  • research and education

Economic Importance for Humans: Negative

There are no adverse effects of black-and-white-casqued hornbills on humans.

Conservation Status

Black-and-white-casqued hornbills are not globally threatened. They are still common in central and eastern Africa, though less so in western Africa. This species is currently locally abundant because it survives in degraded forest and open areas; however, forest degradation in Africa means that hornbills now occur in more open areas with few large trees, which makes them more prone to hunting.. (del Hoyo, et al., 2001)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Abby Velting (author), Michigan State University, Pamela Rasmussen (editor, instructor), Michigan State University.

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.

chemical

uses smells or other chemicals to communicate

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

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

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.

fertilization

union of egg and spermatozoan

forest

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

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).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

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

nomadic

generally wanders from place to place, usually within a well-defined range.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oviparous

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

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

sexual

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

sexual ornamentation

one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.

social

associates with others of its species; forms social groups.

suburban

living in residential areas on the outskirts of large cities or towns.

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

year-round breeding

breeding takes place throughout the year

References

2008. "BirdLife International Species factsheet: Bycanistes subcylindricus." (On-line). Accessed September 03, 2008 at http://www.birdlife.org/index.html..

Kalina, J. 1988. Ecology and Behaviour of the Black-and-White casqued Hornbill Bycanistes subcylindricus in Kibale Forest, Uganda.. PhD Michigan State University, Thesis, 1: 1-100.

Kalina, J. 1989. Nest intruders, nest defense and foraging behavior in the Black-and-white Casqued Hornbill Bycanistes subcylindricus.. Ibis, 131: 567-571.

Kemp, A. 1995. Bird Families of the World: The Hornbills Bucerotiformes.. New York: Oxford University Press.

Kilham, L. 1956. Breeding and other habits of casqued hornbills (Bycanistes subcylindricus). Smith Misc Coll., 131 (9): 1-45.

Lewis, A., D. Pomeroy. 1989. A Bird Atlas of Kenya. London: CRC Press.

del Hoyo, J., A. Elliot, J. Saragatal. 2001. Handbook of the Birds of the World. Barcelona: Lynx Edicions.

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