Bycanistes subcylindricus

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).

• Biogeographic Regions
• ethiopian ethiopian
  • native native

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).

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• forest forest
• rainforest rainforest
• mountains mountains

• Other Habitat Features
• suburban suburban
• agricultural agricultural

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.

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.

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).

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).

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes colored or patterned differently
• male more colorful
• sexes shaped differently
• ornamentation ornamentation

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).

• Mating System
• monogamous monogamous

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).

• Key Reproductive Features
• iteroparous iteroparous
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• oviparous oviparous

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 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.

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.

• Key Behaviors
• arboreal arboreal
• flies
• diurnal diurnal
• motile motile
• nomadic nomadic
• territorial territorial
• social social

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.

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)

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

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).

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.

• Primary Diet
• omnivore omnivore

• 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).

Ecosystem Roles

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

• Positive Impacts
• ecotourism 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..

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

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

References

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.

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